Tuesday, 25 November 2014

Productive Polycultures ? - Polyculture Trials 2014 - Home Garden Records

Over an 8 month period we grew a polyculture on 66.5m2 of land which was cultivated 100% biologically.  From it we harvested 94.68 kg of tomatoes, 6.81 kg of basil, 36.77 kg of beans 10.61 kg of courgette and 12.33 kg of winter squash.  How much time do you think it took to grow this quantity?

The results are in! It's satisfying to have completed the first year study of our annual vegetable and herb polyculture/guild. The results are pleasantly surprising and we're now feeling very encouraged to expand the garden next year.

You can read an introduction to the garden in a previous post here.

Garden Overview   

Climate: Continental Temperate
Latitude: 42°
Elevation: 580m
Average Annual Rainfall: 588.5mm
Co-ordinates:42°42′N 25°23′E

Annual Vegetable and Herb Garden - 66.5m2
Photo taken mid September 2014 by Smilyan Pavlov from  Huma 

Garden Layout 

Garden area: 66.5m2
Cultivated beds area: 36m2
Paths: 30.5m2

Annual Vegetable and Herb Garden.
Path and Bed Layout 

Crop List

66 x Tomato - Solanum lycopersicum
66 x Basil - Ocimum basilcium
36 x Runner Beans - Phaseolus coccineus
36 x French Beans - Phaseolus vulgaris
18 x African Marigold - Tagetes erecta
18 x French Marigold - Tagetes patula
2 x Courgette - Cucurbita pepo
8 x Winter Squash - Cucurbita pepo

The table below shows the floral species composition of each bed including the different cultivars and the dates that the plants were sown or planted.  Beans, courgettes and winter squash were sown. Tomatoes, basil and marigolds were planted.

Other crops such as chilli peppers, parsley, salad chicory and New Zealand spinach were also grown in small quantities throughout the beds to fill in spaces. The yield of these plants, being so small, are not considered in these records. Also not included are the native wild plants that are encouraged to grow around the perimeter of each bed. Many of these plants provide a harvest of salad greens and tea ingredients as well as mulch material within the beds.

Planting Scheme 

Below is a typical representation of the planting scheme within a bed.

Soil Analysis 

Soil samples were taken in early winter and sent to Dr Trendafilov from the Agricultural University Plovdiv.



( mg/100g)

( Р2О5)
( mg/100g)

( mg/100g)


Vegetable Beds-Shipka


Input:Time Spent in Garden  

The total time spent on the garden was 24 hours and 50 minutes, based on one person carrying out all the tasks listed below.  The garden tasks were split into seven main categories. We have the specific activities of each task recorded and would be happy to share our spreadsheets. Send us an email or leave your details below if you would like this information.

Set up/Pack up - 420 minutes
Planting and Sowing - 241 minutes
Weeding - 249 minutes
Tomato care - 420 minutes
Mowing paths -  89 minutes
Summer/ Autumn Mulching - 41 minutes Irrigation - 30 minutes

Input: Fertility

67.2L -  Planting out compost (applied as top dressing to each plant when planted out) 400ml per plant
32.8L - Seedling medium (applied in "nests" made in the straw to facilitate better germination of the seeds) 400ml per nest
120L - Compost - 20L per bed
30L - Ash - 5L per bed
9 Straw Bales - 1.5 bales per bed
33kg Comfrey (fresh cut weight) - 5.5kg per bed

Output: The Harvest 

The total produce from each of the main crops in the polyculture were as follows. 

TomatoSolanum lycopersicum : 94.68kg
BasilOcimum basilcium : 6.81kg
Fresh Runner Beans - Phaseolus coccineus and French Beans - Phaseolus vulgaris : 34.47kg
Dried Runner Beans - Phaseolus coccineus and French Beans - Phaseolus vulgaris : 2.3kg
CourgetteCucurbita pepo : 10.61kg
Winter SquashCucurbita pepo :12.33kg 

The crops were weighed directly after harvest. Only produce of marketable quality was recorded.


Table showing recorded Input and Outputs throughout the season April 2014 - November 2014


  • Records do not include the gathering of materials, compost, tools, plants etc, and assumes that everything is on site ready to go. Harvesting was not recorded although we do intend to record this next season.
  • We grow our own plants from seed, make our own composts and sowing mediums, grow our own summer and autumn mulch, save seeds from tomatoes, basil, marigolds and beans. The support materials (stakes and bean poles) needed for the garden are harvested from a nearby alder coppice. Therefore we have not included this cost in our records. 
  • This year we experienced above average quantities of rainfall regularly dispersed throughout the growing season. This lead to reduced time spent on irrigation.We irrigated during the "dry season" (mid July - mid September ) once as opposed to a normal year where we would irrigate approximately once a week during this same period.
  • The moist conditions resulting from high rainfall created below optimal conditions for tomato growth and provided  ideal conditions for tomato disease to proliferate. Many local tomato growers lost their entire crops without a harvest. Furthermore, early season temperatures were far from ideal resulting in slow fruiting of the tomato crop. Records from previous years show first tomato's harvest around  Mid June as opposed to this year 22nd July. The above mentioned disease also resulted in the early demise of the plants with the last harvest of poor quality fruits (not included in the total) recorded on the 26th September in contrast to mid October in previous years.
  • The garden usually includes chickens in mobile pens however we did not use the chicken tractors within the garden this year. The reason for this was due to the uncertainty of obtaining a valid measurement of the fertility inputs of the chickens.  Furthermore, we wanted to make the design as easy to replicate as possible.
  • We have lots of beneficial habitat and high biodiversity designed into the surrounding garden area that serves to attract pest predators and pollinators, repels pests and provides fertility to the garden as a whole. It would be very interesting to set up a control study on another site nearby without the high levels of biodiversity and designed habitat to see how the harvests compare.      

Improvements for Future Studies 

Biodiversity Study 
We would like to add a measurement of biodiversity to the records and chart how this changes from year to year. Specifically, we would like to look at soil microbiology and invertebrate diversity.

We could begin a measure of soil microbiology by sending samples to a lab. This will be quite expensive and we do not have the finances available for this at the moment.

For the invertebrate study we could practice similar methods as the "Plants for Bugs" experiment carried out by the expert team at RHS Wisley, wherein  invertebrate samples are taken on five occasions throughout the year. The samples are gathered using pitfall and baited refuge traps for ground fauna, and direct observation of flying insect visitors and those settled on the plants. We are currently seeking collaboration with entomologists that could assist us with this part of the study.

Recording  Harvest Time
Next season we will record the time it takes to harvest the produce. We estimate this to be around the same amount of time it takes to establish, plant and maintain the garden, i.e 25 hrs. The time it takes to harvest in such a system will be longer than within a monoculture due to the increased distance between plants and the natural way that they are allowed to grow. For example, the beans tend to tangle making it time consuming to locate the pods without damaging shoot growth.

Soil Samples
Soil samples were taken in early winter after the ash was added to the beds. This was a mistake and this year we have our samples before ash and other fertlisers have been applied.

Sharing, Feedback and Collaboration 

We have our record keeping spreadsheets on Google Docs. These spreadsheets include the details of work undergone in each labour "Input" category, the dates and weights of each harvest, and  materials and tools used . We would be happy to share these - just drop us an email or leave a comment below with your contact details. We would also be happy to hear your suggestions and feedback on how you think we could improve the record keeping for the future and hear about similar results from other guild/polycultures you may have heard about or established yourself. Lastly, if you feel you have something to contribute to our study, we would be happy to receive your assistance.    

If you have enjoyed this post and appreciate the work that we are doing please consider donating to our Polyculture Project and help us expand and excel our research into permaculture and regenerative practices.

We offer a range of plants and seeds for permaculture and forest gardens from our plant nursery including a new range of fruit and nut cultivars well suited to natural gardens. Delivery to all over Europe available from Nov - March

Want to learn how to create regenerative landscapes?  Join us this summer for our Regenerative Landscape Design Course.

 Balkan Ecology Project Bio-Nursery 

Thursday, 13 November 2014

Wood Ash: Natural Fertliser for the Ecological Garden/Farm

As winter approaches we are again lighting fires in our household that provide us with a weekly supply of wood ash which, as this post will describe, can make an excellent additive within the ecological garden/farm.    

Wood Ash: Potassium Fertiliser 

Ash from wood fires, such as bonfires or wood burning stoves, provide a natural source of potassium (K) and other trace elements. Potassium is a major plant nutrient associated with flowering and fruiting. The levels of potassium in ash will vary depending on the age of the wood that was burnt; young wood from pruning will have higher potassium content than older, thicker branches.

Wood Ash: Raising  pH

Soil pH is the measure of the acidity (sourness) or alkalinity (sweetness) of a soil. A simple numerical scale is used to express pH. The scale goes from 0.0 to 14.0, with 0.0 being most acidic, and 14.0 being most alkaline. The value, 7.0 is neutral - i.e., neither acid or alkaline.

Applying wood ash to your soil will raise the pH, reducing the acidity of soils. The majority of vegetables grow best in soils with a pH of 6.5, so testing the level before adding the ash is recommended so as not to raise the pH too much (greater than pH 7.0). However, where club root is present, wood ash can be used to raise the pH to as much as 7.5 to inhibit this disease and still provide good conditions for plant growth.
Intensive vegetable production tends to push soils to the acidic side of the scale, so the addition of ash can help to keep pH at optimal levels whilst providing essential nutrients to your plants.

Most fruits perform best in slightly acidic soil so be aware of the current soil pH and optimal pH of your fruits before applying ash. High pH can be detrimental to acid loving fruits such as blueberries and cranberries. Below is a list of optimal pH ranges for some common fruits and vegetables.  

Table showing optimal pH range for Fruits and Vegetables 

When to use wood ash

If applying wood ash directly to soils, do this in the winter and rake or dig it in lightly to allow the compounds in the ash (which could scorch plants) to react with the moist soil and be rendered harmless before spring sowing or planting.

You can use wood ash in your compost piles at anytime of the year, applying a sprinkling on top of every 15 cm of material. Heavier use risks the presence of high levels of alkalinity and soluble salts which could damage both plants and the soil.

Wood ash can also be used to reduce the acidity in a worm farm. Worms dislike acidic conditions and prefer neutral pH (7). They will stop breeding and start to migrate from the farm if acidic conditions persist. How much ash you use is determined by the size of your worm farm  and the current pH. Having a pH reader and experimenting with quantities of ash is a good way to maintain optimal conditions in the worm farm.  

How to use wood ash

Wood ash can be spread directly on soil in the vegetable garden in late winter at a rate of 50-70 g per sq m; Fork in, rake over or add to chicken tractors and the chickens will work it into the soil for you. It may be useful to sieve the ash before use to remove debris.

Where wood ash is applied frequently to the vegetable plots, it is worthwhile to use a pH test kit to monitor changes in pH and prevent levels rising over pH 7.5
Never leave wood ash in the rain, as the potassium (a useful plant nutrient for flowers and fruit) is in a soluble form and is easily leached out
Apply wood ash in small amounts to the compost heap where, once mixed in, it will blend readily with other materials. As a general guide, you should not be able to identify it after mixing it into the compost.

Things to consider 

  • Avoid using too much wood ash as an excess in alkalinity can be detrimental to some plants.
  • Avoid using ash from treated timber as they may contain potentially harmful residues.
  • Avoid using wood ash on areas where potatoes are to be grown the following spring, as the alkaline conditions can encourage potato scab
  • Ash from coal or anthracite has little or no nutritional benefit and is potentially harmful to soil, plants and consumers of edible produce. 
  • Ash from lump wood charcoal can be used as recommended for wood ashes. 

We offer a range of plants and seeds for permaculture and forest gardens from our plant nursery including a new range of fruit and nut cultivars well suited to natural gardens. Delivery to all over Europe available from Nov - March 

Want to learn how to create regenerative landscapes?  Join us this summer for our Regenerative Landscape Design Course.

 Balkan Ecology Project Bio-Nursery 

Friday, 12 September 2014

The Planting Legacy

Perhaps a motivational force behind the creation of a forest garden may be attributed to the egotistical tendencies of Homo sapiens. It could be that the act of creating perennial, self generating ecosystems that survive as a living legacy to our temporal existence is a glory lure. Anyhow, its a form of glory seeking that I hope catches on :)      

Narcissistic tendencies aside, its always a huge pleasure to watch a plant you have grown from seed mature to the stage where it is ready to take its permanent position in the soil. Even more so when that plant is a long lived specie that will likely be standing proud for your great grand children to admire.

I am having trouble  finding  a place in the garden for more trees and shrubs lately so have started to move plants into a developing forest garden/market garden on the outside of our village.

Swale dug, mulched and filled. 

Thanks to the help of previous course participants and volunteers (thanks guys and girls), the site is already landscaped with swales and water channels and ready to receive the new population of plants.

Autumn is a great time to plant out. The adequate rainfall and, consequently soil moisture levels at this time of year are perfect for the newly establishing plant roots.  Although it may be cold above ground, the warmer soil temperatures make it possible for plant root growth to continue for longer and settle in before the spring growth bonanza.

 I thought I would put together a step by step guide to planting out including a few things to consider before and after planting.

Planting out Guide  

A few things to consider before planting 

  • The best time to plant is when the soil is moist after a rain. If the soil is very wet, treading can cause compaction so avoid working on very wet soils particularly if you have clay.
  • In choosing the position for your plant bear in mind the light, fertility, water, temperature, space and community needs of the organism.
  • Consider the maximum size of the plant and how it will relate to the surroundings of the position you have chosen.
  • For plants that require cross pollination  or are  dioecious you will need to consider the pollination needs and make sure you have a pollinator in the vicinity.  
  • If you are planting bare rooted plants ensure that the roots are not exposed to direct sunlight for too long and that they do not dry out.

 Planting instructions

  • Dig your hole sufficiently big to allow some space around the root ball or roots i.e do not cram the plant into a small hole. Twice the diameter of your pot is adequate.  
  • When digging, separate the top soil and sub soil layers. This is best achieved by placing two boards or tarps next to your hole. Dig the top soil out and pile it on one board/tarp, now dig the subsoil out and pile it on the second board/tarp.
  • Make sure the bottom and sides of your hole are not compacted from digging. If there are any smeared surfaces, scrap them loose with a fork. This ensures easier access into the soil for the establishing roots as well as providing good drainage and air spaces.    
  • Water the empty hole well and allow time for the water to drain away. If your plant is in a container then rough up the sides of the root ball. The purpose of this is to ensure the fine roots make good contact with the soil when you infill the planting hole.
  • Due to the fast draining sandy loam I normally work with I plant a little lower than ground level to provide a dish for water to collect in. If you have poor draining soil (heavy clay) and or a  high water table then you should consider planting higher then ground level.
  • If your planting site has a history of intensive application of fungicides you should re-establish the Mycorrhizal community.  Mycorrhizas are symbiotic relationships between fungi and plant roots (the term means literally 'fungus root'). They are very common on crop plants as well as in wild plant communities, and in several cases they have been shown to be important or even essential for plant performance. The fungus obtains at least some of its sugars from the plant, while the plant benefits from the efficient uptake of mineral nutrients (or water) by the fungal hyphae. You can reestablish the Mycorrhizal community  by simply adding half a spade full of soil from a  healthy soil ecosystem nearby which should contain many of the beneficial fungal organisms. Mix the healthy soil with your pile of top soil.   
Picture shows how the plant can draw upon a much larger pool of soil resources with the assistance of  mycorrhizal fungi
  • Back fill the hole with the sub soil first, pack the soil in firmly around the roots or root ball and then add the top soil, again tampering the soil firmly to ensure good contact is made between soil and roots. The idea behind keeping the soil layers in order is to create minimum disturbance to the existing soil ecology. It may just look like plain earth but there are a myriad of organisms at work in there.       
  • You can remove surrounding vegetation to approx 50cm radius of the plant stem so you end up with a circle of bare earth approx 1m diameter with your plant in the centre.  If your plant is small then you can make this area smaller.       
  • Imagine which way the water would flow across the land surrounding your plant and pile up the organic matter you have scrapped away from the surface along with any left over soil  to create a barrier that will  block the water from moving away from the plant. You want to keep the water around the plant where it can drain into the soil slowly and soak through to the roots below ground. It may be that on flat ground you need a barrier surrounding the plant creating a dish in which the water fills. If you have a low water table,  lots of rain in your area and poor draining clay soil then this is not advisable.   
  • Water the plant again applying more water then you think you will need and watch to see how well the water stays around the plant root zone. If you see the water escaping make some amendments to your barrier. 
  • Once the plant is watered apply mature compost, approx 2-3 cm deep, covering  the bare earth and  place wet card board sheets or old clothing or cloth over the compost. If more than one piece of cardboard is needed overlap the cardboard so there are no gaps. This layer  provides a barrier to prevent weed seeds in the soil from germinating and will decompose to add extra fertility to the soil. You can also buy mulch mats. 
  • Cover the cardboard/cloth with a further 3cm of well matured compost and then cover this with a 10cm layer of straw mulch (or other seedless mulch).   
  • In order to prevent collar rot it is very important to make sure that the soil and mulch layers are not in direct contact with the bark around the base of the stem . To allow air circulation, be sure to clear away the mulch and compost from that area so that you end up with a visible gap of at least 5 cm between stem and soil. You should check this every so often as the mulch usually makes its way back around the collar

Aftercare considerations   

  • If planted in Autumn it is likely that your new plants will not need watering until the mid spring. Keep an eye on your plant and water if you see/feel the soil below the mulch is dry. Its important to keep the plant from drying out in the first few years so plan time to monitor. 90% of all problems with newly-planted trees are because the steward didn't water them.
  • If planting a tree whip, according to some reports and contrary to popular belief, staking is not necessary.  It is claimed to be counter productive and discourages a young tree from forming strong and secure anchor roots. Large container trees will however need staking. 
  • Tree barriers are recommended to prevent herbivores committing planticide and according to the manufactures have many other purported benefits ;) I have never used these so cannot comment.     
  • Check your plant from time to time and make sure the mulch has not made its way back around the stem collar. Keep the area weed free for a few years by topping up the cardboard and if you have planted a tree with high nutrient demands apply extra compost the following autumn. 
  • Finally, enjoy your plant.       

We have a great selection of trees, shrubs and herbs reared at our small but growing Bio Nursery. We can deliver plants to anywhere in Europe so take a look at our stock list and get in touch to make an order,

Interested in Ecological methods of growing food? Check out our Upcoming Courses and Events

We offer a range of plants and seeds for permaculture and forest gardens from our plant nursery including a new range of fruit and nut cultivars well suited to natural gardens. Delivery to all over Europe available from Nov - March 

 Balkan Ecology Project Bio-Nursery 

Sunday, 27 July 2014

The Plum Moth - Grapholita funebrana

You may have come across small pinkish maggots in a plum before. The maggots are often found near the stone accompanied by tiny parcels of dark coloured material. These are Grapholita funebrana, the Plum Moth and more specifically, the caterpillar (larva) of the Plum Moth. The dark coloured material is their droppings (frass).

Larva of Grapholita funebrana (Plum Moth) observed  in early - mid summer

During this post we'll look at the life cycle of the Plum moth and some ways to prevent them in the biological garden.

Whilst picking plums in late August from a plum tree in our garden I noticed that the Plum Moth larvae so frequently found in the early ripening fruit from July - early August were absent from the later ripening fruits. I assumed it must have something to do with the organism's life cycle and so embarked upon a little research to find out more.

G. funebrana (Plum Moth) emerges from a cocoon as an adult moth from late May - mid July. The adult moths mate with each other and the females then proceed to lay their eggs on the small ripening fruits. Caterpillars (larvae) hatch from these eggs, tunnel into the fruits and feed on the "flesh" around the stone until fully fed. At this point the caterpillar (larva) emerges from the fruit and finds a cozy concealed spot either in the tree, on surrounding fallen dead branches or in the soil. Here they spin a silk cocoon (pupa) in which they overwinter, emerging as adults in the spring.  If climatic conditions are favourable, some first generation caterpillars may pupate early and emerge as adults later on in the same season,  laying their eggs in the ripe fruits. Three generations during spring and summer have been reported in some places.     

Adult  Grapholita funebrana 4 -7.5 mm long

We always have a long warm summer here and two generations are likely. It seems the bulk of our plums ripen before the second generation can begin to do damage. The early plums that are infected make good fruit for drying. We cut the fruit in two, collect the larva for the chickens, scrap off the tiny amount of frass and leave to dry on a tray in the car with the windows slightly cracked. They are delicious :)
In our gardens the plum moth does not really bother us, however when growing fruit on a larger scale this organism can cause significant loss to a harvest. This specie and other members of the genus Grapholita are commonly associated with many plants in the Prunus Genus, and Grapholita funebrana is one of the most important lepidopteran pests of fruit in Europe.  Larvae can cause significant damage to apricot, cherry, peach, plum, and other Prunus species. The following are signs of infestation:
  • Presence of eggs on fruit and fruit stalks.
  • Entry holes on fruit surface.
  • Dissecting a suspicious fruit may reveal larvae or frass in flesh near the seed.
  • An infested fruit may show symptoms such as discoloration, gummy droplets oozing out of the caterpillar’s entry hole, premature ripening and fruit drop.



Having a good understanding of the "problem organism"  is crucial to providing solutions and can help us in a number of ways
  • We may be able to prevent the organism becoming a problem altogether by putting in place effective control measures that break the pest's life cycle before it becomes a nuisance.   
  • We will know at what stage an organism is going to inflict damage on a crop.
  • We will know when the organism is most vulnerable to means of control.
  • We will know what we are looking for and will be able to identify a problem early on.
To recap on the Plum Moth life cycle we have the following stages:  Adult - Eggs - Larva (caterpillar)- Pupa (cocoon).  At each stage it may be possible to reduce the population numbers.    

The adults are most active between 18 and 22°C. The moths rest on the tree leaves during the day, becoming more active after sunset. The adult moths are generally sexually active before sunrise and lay most of their eggs in the evening. A healthy diverse garden/farm ecosystem will naturally support many bird and bat species who feed on the adults moths and larval stages. We can focus these allies by placing bird feeders in fruit trees particularly when the the temperatures rise above 18C.  Commonly used commercially is the Phereomone trap. This trap gives off the pheromone (the secreted or excreted chemical factor) of the female moths, thereby attracting male moths and trapping them thus preventing mating. It's costly and time consuming and is not100% effective.

The Eggs are deposited by adults around sundown at temperatures around 25°C. The females deposit 3 to
5 eggs per fruit. Eggs hatch in about 1 to 2 weeks. It's not at all practical to intercept at this stage.

The Larva is the stage of the life cycle that one is most likely to come across and can easily be removed with the infected fruit and destroyed, thereby preventing future generations. The fact we feed the larvaa to the chickens when preparing the early fruit for drying prevents further propagation and is why it's important not to let fallen fruit accumulate under a tree.  

Pupa:The larvae pupate in bark crevices or protected areas in the soil. Poultry are expert foragers for small parcels of nutrients such as a pupa. By arranging a coop around the base of your fruit trees during late May to mid July the poultry will scratch relentlessly for foods such as the Pupae and deliver some welcome nutritional excrement whilst at it. Blue and Great Tits feed on the pupa and can be attracted to the trees with balls of fat and seeds. French research has found that an adult tit can consume 12000-18000 of hibernating moth caterpillars per year. Hanging feeders in trees during the winter is also of benefit.             

Relentlessly at work in the compost pile.

We can also mitigate the damage done by these organisms by considering the host plant. We may be able to establish good control of the specie on our site, but if there are plums trees in neighbouring gardens or wild plums in the windbreaks or hedgerows and the fruit is unpicked, local populations may grow rapidly and soon be looking for new breeding/feeding grounds.

When considering growing plums, it's well worth observing local plum trees and other host species for signs of the Plum Moth. By studying the fruit of local wild plums or organically grown plums along with average temperatures records,  you may be able to work out at what point the fruit ceases to be infected and choose a variety that ripens during the time period between generations. You may also observe that the wild fruits are not that troubled by these pests at all . It appears to me that many of the local wild plums Prunus cerasifera and Prunus insititia in the relatively undisturbed (wild) areas around us are largely unaffected by the Plum Moth but that the isolated trees in fields, garden trees and trees in poor locations (i.e compacted soils) tend to be targets. Perhaps trees in healthy communities can repel the moths in some way?    
Prunus cerasifera - Myrobalan Plum / Cherry Plum

Susceptible Cultivars 

Some Plum cultivars are noted for being more susceptible to damage from the Plum Moth such as Czar and Victoria as well as Amers, Anna Spath, Buhlertal Prune, Emma Leppermann, Italian Prune, Lowan, Stanley, Valjevka, Valor and Wangenheim Prune. (Agroforestry Research Trust Volume 9 No.1 pg3). 

If you would like to learn more about Grapholita funebrana - Plum Moth , it is worth noting that it is often referred to as Cydia funebrana in older literature.

Interested in Ecological methods of growing food? Check out our Upcoming Courses and Events

We offer a range of plants and seeds for permaculture and forest gardens from our plant nursery including a new range of fruit and nut cultivars well suited to natural gardens. Delivery to all over Europe available from Nov - March 

 Balkan Ecology Project Bio-Nursery 

Tuesday, 1 July 2014

Nitrogen Fixing Species for Agroforestry Systems

I am currently working on a Regenerative Landscape Design for a site in Todorovo, Bulgaria. The plan is to establish an Agroforestry system known as Alley Cropping wherein rows of mixed species edible trees and shrubs are planted at intervals with spaces for herbs, forage and/or grain crops to be grown in between. It's a dynamic system which is inherently diverse, providing multiple yields and excellent habitat for wildlife while at the same time being relatively resilient to a changing climate.

The site design - Paul Alfrey 

An essential component of the design will be the Nitrogen fixing perennial plants within the community of fruit and nut trees. These plants will be pruned at regular intervals to provide biomass for surface mulch and to release a biological source of nitrogen to the surrounding productive plants and soil life by means of root shed associated with top pruning. 

When selecting plants for the Nitrogen Fixing component of this design, I was looking for species that could withstand record lows of -28 (Zone 5), tolerate some shade, were fast growing, tolerant of trimming and coppicing, able to grow in clay soils, known to provide significant quantities of nitrogen, easy to propagate from seed and provide some food for humans and other animals. The following plants fit the criteria.
  • Elaeagnus angustfolia - Oleaster, Russian Olive
  • Elaeagnus commutata - Silverberry, Wolfberry
  • Elaeagnus umbellata - Autumn Olive. Autumn Elaeagnus
  • Caragana arborescens - Siberian Pea Tree
 We are planning to grow the nitrogen fixing plants for this site from seed and to involve the local community in doing so.  Many local people, particularly the older generation are skilled horticulturalists with many seasons of experience behind them. We hope to include a number of these people in the process of propagation, each one functioning as a individual unit.  This will keep the propagation process small scale, making it far easier to use biological methods. The propagation will begin in the autumn as Elaeagnus spp. all require cold stratification unless they are sown immediately after they are picked. Caragana aborescens  will be sown in the spring 2015.    

The Benefits of Propagating from Seed

When I first started growing shrubs from seed I was pleasantly surprised at how fast the plants establish. In my experience from growing these and other nitrogen fixing shrubs, seeds germinating in the spring can establish well and be ready to plant out in the autumn of the same year (subject to species hardiness and, of course, the weather conditions in a given year). The following spring after autumn planting, I practice  formative pruning to encourage the shrubs to become denser and by the third summer after sowing  I have recorded growth of up 80cm high and 60cm wide specifically for Elaeagnus angustifolia .  The growth I have witnessed from plants in my own stock have, in some instances, outperformed established 6 year old plants I have growing in the garden, purchased from a commercial nursery.

When propagating from seed you have the advantage of selecting the strongest seedlings.  Another significant reward is that you are promoting genetic diversity within your populations, something you are not likely to find in the majority of cloned nursery stock.

If you would like to grow your own nitrogen fixing plants we are have a supply of excellent seeds at very reasonable prices currently only available to our blog readers (see below for more details).

Plants Profiles for the Nitrogen Fixing Component of this Design.


Elaeagnus angustfolia - Oleaster, Russian Olive

Overview:A deciduous large shrub or small tree from Europe and W.Asia, growing approx 7m high and 7m wide. Hardy to zone 2 (-40C), tolerates part shade, salt and air pollution.
It has silvery branches often thorny, with silvery scales when young, silvery willow-like leaves, silvery flowers in June and yellowish-silvery fruits ripening in October. Plants prefer continental climate.    
This specie is often cultivated in Europe and Asia for its edible fruits (there are many named varieties some of which are thorn less). The plants begin to flower and fruit from three years old. It is very tolerant of pruning even right back into old wood. The flowers are sweetly scented. Fruits hang on the plant for much of the winter providing a valuable source of winter food for birds. The fruit is readily eaten and disseminated by many species of birds. This species is considered invasive in the United States.

Uses: Edible fruit -raw or cooked as a seasoning in soups. The taste is dry sweet and mealy. The oval fruits are about 10mm long and contain 17 amino acids with total sugars making 54%of the composition. In China they are made into a beverage
Expected fruit yields are 7-9kg per plant. The seed is edible raw or cooked. The seed oil, flowers and leaves are used medicinally. Plants can be grown as a hedge in exposed positions, tolerating maritime exposure. An essential oil obtained from the flowers is used in perfumery. A gum from the plant is used in the textile industry in calico printing. Leaves are used as goat and sheep fodder. The wood is hard, fine-grained and used for posts, beams, carving, domestic items and makes good fuel. The plant is attractive to bees and is known to be grown as a biomass crop on a 3 year rotation. In Pakistan it is valued as a pollard fuel and fodder crop.      

Nitrogen Fixing Potential: This specie is classified by USDA as being a HIGH nitrogen fixer with estimated yields of 160+ lbs/acre or 72>kg/4050m²

Propagation:Establishment and reproduction of Elaeagnus angustifolia is primarily by seed, although some spread by vegetative propagation also occurs. Cold stratification required for 30-60 days.

Elaeagnus commutata - Silverberry, Wolfberry


Overview: A medium deciduous shrub from N.America, typically growing 3m high and 1.5m wide but sometimes double that. Hardy to zone 2 (-40C). Branches are thornless and reddish-brown, leaves are silvery on both sides . A profusion of fragrant silvery flowers appear in May-June, followed by round silvery fruits ripening in September. It typically grows on dry to moist sandy and gravel soils in steppes, meadows or woodland edges. It tolerates very alkaline soils. Plants prefer a continental climate. It can regenerate from old wood making it a good coppice plant. It resents root disturbance. Plants produce suckers quite freely often sending them up at some distance from the plant. Plants start to fruit often after 2 years.

Uses: edible fruit, raw or cooked, good with soups and for making jelly. Edible seed, raw or cooked. Plants can be grown as a hedge in an exposed position, tolerating maritime climate. The fibrous bark is used in weaving and rope making. Dried fruits are used as beads. Flowers provide nectar for bees. Cultivated as an ornamental plant for its silvery foliage.    

Nitrogen Fixing Potential: The species is classified by USDA as being a MEDIUM  nitrogen fixer with estimated yields of 85-160lbs/acre or 39-72kg/4050m²

Propagation: Seed is  best sown as soon as it is ripe in a cold frame. It should germinate in late winter or early spring, though it may take 18 months. Stored seed can be very slow to germinate, often taking more than 18 months. A warm stratification for 4 weeks followed by 12 weeks cold stratification can help. The seed usually (eventually) germinates quite well.

Elaeagnus umbellata - Autumn Olive. Autumn Elaeagnus 


Overview: A large deciduous shrub from E.Asia, growing 4.5m high and 4.5m wide, hardy to zone 3(-35C)
tolerates part shade, very drought tolerant. Branches are often thorny, leaves are bright green, silvery beneath. Yellowish white, fragrant flowers, are produced in May-June, followed by rounded silvery brown (ripening red) fruits in Sep-Oct.  Sometimes cultivated for its edible fruit. There are many named cultivars. Flowers are rich nectar and very aromatic.Plants can fruit in 6 yrs from seed. This specie is considered weedy in the U.S

Uses: Edible fruit raw or cooked which is very tasty and can be made into jams, preserves etc. The fruit contains about 8.3% sugars. 4.5% protein. 12mg per 100mg Vitamin C. Mature bushes in the wild yield about 650KG of fruit over 2-3 pickings . The harvested fruit stores for appox. 15 days at room temperature. It can be used as a hedge plant and tolerates maritime exposure succeeding in the most exposed positions. The wood is a good fuel. The nectar from the flowers is attractive to bees comprising 28% sugars. The plant is used as a nurse tree, when planted with fruit trees it is reported  to increase the overall yield of the orchard by 10%. It can also be grown as a biomass crop on a 3 year rotation.   

Nitrogen Fixing Potential: The species is classified by USDA as being a MEDIUM  nitrogen fixer with estimated yields of 85-160lbs/acre or 39-72kg/4050m²

Propagation:Seed - best sown as soon as it is ripe in a cold frame. It should germinate in late winter or early spring, though it may take 18 months. Stored seed can be very slow to germinate, often taking more than 18 months. A warm stratification for 4 weeks followed by 12 weeks cold stratification can help. The seed usually (eventually) germinates quite well. Prick out the seedlings into individual pot as soon as they are large enough to handle and plant out when they are at least 15cm tall.

Caragana arborescens - Siberian Pea Tree 


Overview: . A deciduous shrub originating from Central Asia  belonging to the Fabaceae (legume) family  growing to 5-6m high and 4m wide with an upright habit. It is vigorous. Flowers are borne from buds on the previous years wood and are typical of flowers from this family. Flowering occurs in May. Pollination is via bees, usually wild bumble bees.  Pods develop from flowers looking like small pea pods, they are 4-5 cm long. The pods ripen to amber or brown from June -July onwards and seeds fall by August. The plant is extremely hardy tolerating winter temperatures of -40 Hardiness zone 2. Prefers a continental climate witrh hot dry summers and cold winters.
Uses: The young pods are eaten as a vegetable, lightly cooked. The pods become tough later in the season. The seeds are rich in fats and proteins (12% and 36% respectively) about the size of lentils and can be cooked and used in any way that beans are used (the cooked flavour is somewhat bland, so best used in spicy dishes ). The young raw seeds have a pea-like flavour although it is not clear whether they should be eaten raw in much quantity. Widely used in windbreaks and shelter belts and used in wildlife-erosion control plantings stabilizing soil with an extensive root system. Good wildlife fodder and can be used to as poultry food. A fiber is obtained from the bark and used for rope making.          

Nitrogen Fixing Potential: The species is classified by USDA as being a MEDIUM  nitrogen fixer with estimated yields of 85-160lbs/acre or 39-72kg/4050m²

Propagation: Seed propagation is the norm. Seeds germinate better after a short period of stratification and/or soaking in warm water  prior to planting.

These species profiles include extracts by Martin Crawford, Director of Agroforestry Research Trust from the excellent quarterly publication Agroforestry News Vol.4 No.3. I highly recommend subscription to this journal as essential reading for all who are interested in temperate tree crops and agroforestry. Put a log of Krugiodendron ferreum on top of an issue and it will still be worth its weight in gold :)

If you would like to grow your own we are offering great prices for excellent seeds.

Nitrogen Fixing Shrubs and Trees

1000 x Hippophae rhamnoides - Sea Buckthorn - £12 / €15 inc. delivery
1000 x Alnus incana - Grey Alder - £10 / €14 inc. delivery
1000 x Elaeagnus umbellata - Autumn Olive- £10  €14 inc.delivery
1000 x Caragana arborescens - Siberian Pea Tree - £10 / €14 inc. delivery
500 x Elaeagnus commutata - Silverberry, Wolfberry - £10 / €14 inc. delivery
500 x Elaeagnus angustifolia - Russian Olive - £10 / €14 inc. delivery 

Multi pack including 1 pack of each of the above -  £50 / €67 inc. delivery 

Seeds - Edible Fruit and Nut / Timber Species 

500 x Celtis occidentalis - Hackberry - £12 / €15 inc. delivery
500 x Prunus serotina - Rum Cherry - £10 / €14 inc. delivery
100 x Pinus koraiensis - Korean Pine - £12 / €15 inc. delivery

Multi pack including 1 pack of each of the above - £30 / €40 inc. delivery

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  • Delivery is included in the price. We use tracked and recorded  international courier. 
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