We're extending our Polyculture Project to include experimental perennial polycultures. Our aim is to develop models that are low cost to establish and maintain, can produce healthy affordable nutritious food and will enhance biodiversity.
This spring we'll be including the Early Polleniser Polyculture as presented here. The design aims to provide pollination support for farms and gardens, yields of nutritious fruits and nuts, valuable nesting sites for endangered nativebees, and spectacular flower displays to shake off the winter blues
As the title suggests the primary purpose of the Early Polleniser Polyculture is to provide an early source of pollen/nectar to a wide diversity of pollinating insects. The majority of the plants in this polyculture bloom when there is little other sources of nectar/pollen available. This encourages pollinating insects in and around our gardens to fulfill their vital role when the crops (particularly fruittrees) start to flower in the early spring.
The polyculture also provides a source of produce in its own right and with proper cultivar selection and plant care, should provide high yields of nutritious fruits and nuts as well as habitat for a wide range of wildlife and pollinators.
The Early Polleniser Polyculture
Before we go any further I'll quickly clarify the meaning of the term Polleniser.
A polleniser (sometimes pollenizer, pollinizer or polliniser) is simply a plant that provides pollen. The word pollinator is often mistakenly used instead of polleniser, but a pollinator is the biotic agent that moves the pollen, such as bees, moths, bats, and birds. Bees are thus often referred to as 'pollinating insects'.
Bee (Pollinator) and flowering plant (Polleniser)
All species included in the polyculture apart from Trifolium repens - White Clover, flower during the months of January - March and provide valuable pollen or nectar forage for bees and other pollinators during this period.
Early Polleniser Guild species in flower
Design Goals - As well as pollination support, wildlife habitat and fruit production the design goals include
For the polyculture to be functional on marginal sites i.e shady areas, low fertility soils, areas exposed to wind. The early polleniser guild is primarily a support polyculture with the primary function of providing main crops with pollination support so we may not want to allocate the most productive land to it.
That the polyculture should have relatively low time/cost inputs. Once established the polyculture should require little to no external fertility and approx. 5-7 hrs of maintenance per year in the late autumn. (not including harvest times). Maintenance and management of this polyculture is further discussed below.
That the polyculture can be of use on a small and broad scale. The design presented above represents one unit and can work well "stand alone" in any garden. Multiple units of this polyculture can also be used in orchards and farms to provide better pollination coverage for the crops. (see layout options below)
Light and Aspect - All of the plants included tolerate some shade or utilise light when other plants are not in demand of it. The polyculture can therefore be positioned on marginal areas with lower light levels whilst still serving a purpose, however if you would like to obtain maximum pollinator attraction and a higher yield of fruits and nuts, choose a site with at least 6 - 8 hrs a day and orientate from east - west.
Water - Optimal irrigation is a key to healthy and productive plants. This polyculture is not well suited to semi wetlands and areas with a high water table and will not thrive in very dry areas with no access to irrigation. In dry climates irrigation will be essential but selecting a position for the polyculture that maximizes the absorption of rainfall will help considerably and can be achieved by planting on contour and using simple earthworks to keep rain water around the root zones of plants.
N.B. All of the plants are relatively drought tolerant but the fruiting plants will not be high yielding without proper irrigation.
Access - Access from within the polyculture is required for pruning, weeding and harvesting. Two 50 cm wide paths running within and parallel to each other provide this access. The periphery of the polyculture should also be accessible from the outside.
Pollinator Habitat - Native bees are very important pollinators and are some the most endangered species in our ecosystems . Including habitat for the bees to nest as well as providing good quality forage is essential, accordingly this polyculture includes bee nesting habitat, but having other such habitat around a site is recommended.
Species Selection - Our plant selection takes into account the following;
Climatic compatibility with the site
Early nectar/pollen provision
Other benefits to wildlife and production for humans
Flowering periods that do not have significant overlap with crops on the site.
Shrub species that respond well to regular pruning/coppicing
Proximity to crops - Bees will forage where high quality food is available and presumably shorter foraging trips are both safer and more energy-efficient for all bees. Studies show that Honey Bees - Apis spp. will forage many kms away from nesting sites. Bumblebees - Bombus spp. and most solitary bees will typically forage much shorter distances, according to some reports 100 m - 800 m.
Given that there is little consensus within studies of pollinator foraging behaviour, it's difficult to state how far from the crops and to what density this polyculture should be used to achieve the best pollination results. As a presumptive guide, in areas where suitable forage and nesting habitat is lacking assume a beneficial radius of 100 - 300 m and in areas where there are lots of established early forage and nesting sites assume a beneficial radius of 500 m - 1000 m. You can never really have too much early pollinator forage available, but you can have too little. Priorities of budget and time, and the crops that are being grown are other factors that will guide unit quantity and crop proximity decisions.
It's worth noting that plants are in competition for pollinators attention and for this reason the flowering period of the plants in the polyculture do not overlap significantly with crop plants.
Location/Layout - The polyculture unit presented above can work well as a stand alone unit in any garden. Multiple units of this polyculture can also be used in orchards and farms to provide better pollination coverage for the crops. Below you can find three suggested layouts for the broad scale application of this polyculture 1.Border, 2 Island and 3 Alley.
1.Border Layout - The polyculture can be planted on the inside of a fence or outside of a track to form a "wrap around" for the entire orchard/market garden etc. or for subdivision boundaries within a site. Being composed of shade tolerant plants the polyculture will, to some extent, function regardless of aspect. Each unit as pictured above can be repeated to form a border planting.
2. Island Layout - The island layout intersperses the units around the site. For already developed sites the islands can be positioned in difficult to access nooks and corners, shady spots and areas of marginal value, or on the periphery of crops that will benefit the most from enhanced pollination.
3. Alley Layout - The alley layout entails planting the polycultures in an alley cropping or orchard system at intervals among the main crops. For example, an apple and pear orchard may have every 10th row composed of early polleniser units.
So lets take a closer look at the species involved and the management and maintenance tasks required for this polyculture
The Polyculture Components
I've divided the polyculture into 5 main components based on the purpose that each component serves.
Fruiting Trees and Shrubs
Early Flowering Bulbs
1. Fruiting Trees and Shrubs - The Polyculture Components
The fruiting trees and shrubs component include Cornus mas and Corylus avellana in the upper canopy, and Chaenomeles speciosa and Mahonia japonica in the lower canopy/shrub layer and are the main productive units in the guild. With good cultivar selection these plants can provide yields of excellent fruits and nuts.
Cornus mas - Cornelian Cherry
Species Overview - Cornus mas is one of my favorite plants. The hum of the bees under our Cornus mas trees on a sunny day in late winter is just one of the reasons I love this plant. It's a medium sized hardy tree and an excellent polleniser producing a bounty of flowers rich in nectar from Feb - March. The plant is self fertile and the flowers go on to form wonderful grape shaped fruits in late summer delicious when fully ripe.
Four seasons of Cornus mas from our home garden.
Uses: Excellent fruit when ripe and great for making cordial or syrups. Nutritional analysis indicates that Cornelian cherry juices are rich in various essential elements and might be considered as an important dietary mineral supplementation. There are some fabulous cultivars available with larger sweeter fruit.
The seeds can be roasted, ground into a powder and used as a coffee substitute and a small amount of edible oil can be extracted from the seed. A dye is obtained from the bark and the leaves are a good source of tannin. The wood is very hard, it is highly valued by turners and has a history of use for tools, machine parts, etc. We use the twigs to feed rabbits and goats all year around.
Biodiversity - One of the earliest trees to flower, attracting a wide range of pollen and nectar feeding invertebrates from Feb - March. We often see great tits, blue tits and long tailed tits in our trees during the winter. I'm not sure whether they are feeding on the buds, dried fruit or perhaps the invertebrates sheltering under the bark and crevices.
For more on this plant see our Cornelian Cherry plant profile
Corylus avellana - Hazelnut
Species Overview - A fast growing deciduous shrub with rounded leaves, producing yellow male catkins in the early spring followed by delicious edible nuts in the autumn. Typically reaching 3–8 m tall but may reach 15 m.
Corylus avellana - Hazelnut
Uses: One of the finest temperate nuts eaten roasted or raw. The wood from hazel is also commonly used. Soft, easy to split but not very durable it is mainly used for small items of furniture, hurdles, wattles, basketry, pea sticks etc. The tree is very suitable for coppice. The twigs can be used to feed rabbits and goats all year around The nuts also contain 65% of a non-drying oil that can be used in paints, cosmetics etc. The finely ground seeds are used as an ingredient of face masks in cosmetics.
Biodiversity - The pollen-bearing catkins can be available to pollinators from as early as late Jan - late March. Hazel leaves provide food for the caterpillars of many moths. Hazel nuts are used by dormice to fatten up for hibernation and in spring the leaves are a good source of food for caterpillars, which dormice also eat. Hazel nuts are also eaten by woodpeckers, nuthatches, tits, wood pigeons, jays and a number of small mammals.
For more on this plant see our Hazelnut plant profile . We also have a range of excellent cultivars available
Chaenomeles speciosa - Japanese Quince
Species Overview - A thorny deciduous or semi-evergreen shrub native to eastern Asia, usually growing to about 2 m tall and generally exhibiting a rounded outline, but is somewhat variable in form. The plants establish a very dense crown with a tangled jumble of branches which are either spiny or with spurs. The flowers come before the leaves and are usually red, but may be white or pink. The fruit is fragrant and looks similar to a small apple although some cultivars have much larger pearish shaped fruits. The leaves do not change colour in the autumn.
Chaenomeles speciosa - Japanese Quince
Uses - The fruits don't make great eating and are generally extremely hard but following a cold spell I found the Japanese Quince softened enough to squeeze like a lemon, and the juice being very acidic makes them an excellent alternative to lemon juice. Another plus for this fruit is that they have a delicious and somewhat addictive aroma that lingers around for a few days resembling that of pineapples, lemons and vanilla. We leave the fruits in the car or around a room to act as a natural air freshener.
Biodiversity - The flowers are attractive to a wide range of pollen and nectar feeding invertebrates from March- April, sometimes in February. With regular pruning the shrubs become dense providing suitable nesting habitat for birds such as wren - Troglodytes troglodytes, chiffchaff - Phylloscopus collybita and robin - Erithacus rubecula. The diets of these birds include some common vegetable pests and can help keep pest populations in check.
For more on Chaeonomeles spp. see our previous blog article here.
Mahonia aquifolium - Oregon Grape
Species Overview - A great little shade tolerant evergreen shrub growing to 1 m tall by 1.5 m wide that can cope with most soils and thrive in shady spots where many other plants succumb. It is resistant to summer drought and tolerates wind. The plant produces dense clusters of yellow flowers in early spring, followed by dark bluish-black berries. Once the plant gets going it's very vigorous and produces many suckers.
Mahonia aquifolium - Oregon Grape
Uses - The small purplish-black fruits can be used to make jelly or juice that can be fermented to make wine. The inner bark of the larger stems and roots of Oregon-grape yield a yellow dye; the berries give purple dye. The holly-like evergreen leaves are sometimes used by florists to add to bouquets. It makes a great under story shrub for densely shaded areas.
Biodiversity - Excellent early-flowering nectar source for bees and bumblebees. The nectar and pollen may be taken by blackcaps, blue tits and house sparrows. Berries are eaten by blackbirds and mistle thrushes. Good caterpillar food plant.
For more on this plant see our Mahonia aquifolium plant profile
Fruiting Trees and Shrubs - Unit Management
The table below indicates the quantity of trees and shrubs per unit and some information on how to establish and maintain this component of the polyculture.
Planting scheme for Fruiting Trees and Shrub component
2. Ground Cover - The Polyculture Components
The ground cover plants include Primula vulgaris and Bellis perennis, both herbaceous perennials with low growing and spreading habits that over time should form large patches of cover under and around the shrubs and trees. A ground cover can prevent unwanted plants from moving in and protects the soil from erosion.
Species Overview - A herbaceous perennial, loving cool, damp banks and glades, and thriving in coppice woodland where they can form a stunningly attractive carpet. They like wet soil best, with lots of shade in the summer. The drier and hotter the climate, the more they need shade. Summer drought is not a big problem as long as they get plenty of moisture in autumn and the first part of the year.
Primula vulgaris - Primrose ground cover under a Cornus mas in our garden
Uses: Both flowers and leaves are edible, the flavour ranging between mild lettuce and more bitter salad greens. The leaves can also be used for tea, and the young flowers can be made into primrose wine.
Biodiversity - Primroses are one of the earliest spring flowers. They may be found flowering in warm sheltered nooks as early as the end of January, although most flower from March to May. Because they flower so early in the year, they provide a vital source of nectar at a time when there are few other flowers around for insects to feed on such as adult Brimstone butterflies which have hibernated over the winter and often emerge on warmer winter days.
For more on this plant see our Primula vulgaris plant profile
Species Overview - An abundant, small, low-lying herbaceous perennial plant with white flowers with yellow centres and pink flecks, that appear most of the year, except in freezing conditions. The plants habitually colonise lawns and grassland.
Uses: May be used as a potherb and young leaves can be eaten raw in salads or cooked, noting that the leaves become increasingly astringent with age. Flower buds and petals can be eaten raw in sandwiches, soups and salads. It is also used as a tea and as a vitamin supplement. Medicinally, the plant is known for its healing properties and can be used on small wounds, sores and scratches to speed up the healing process. The spreading habit of the plant makes it a good ground cover option.
Biodiversity - A valuable addition to grassland areas managed for wildflowers and wildlife attracting a good deal of attention from pollinators when little other forage is available.
For more on this plant see our Bellis perennis plant profile
Ground Cover - Unit Management
The table below indicates the quantity ground cover plants per unit and some information on how to establish and maintain this component of the polyculture.
Planting scheme for ground cover is mixed patches of the species between the shrubs and trees