Best Plants for Solitary Bees
The majority of wild bees are solitary species with each female building and provisioning a nest all on her own. The bulk of these species nest in burrows underground, but some are cavity nesters using hollow plant stems and the vacant galleries of wood boring beetle larva to house their nests. In addition to food plants many of these cavity nesting species require specific plant materials to construct their nests.
UK solitary bees
There are over 243 species of solitary bee recorded in the UK. They are found in a wide variety of habitats occupying ecological niches other bees may not take advantage of. Aside from the flower bees Anthophora sp. Most have short tongues and prefer simple open type flowers where they can easily access the nectar and pollen.
Different species of solitary bees are active at different times of the year and can be grouped by their flight periods. Many species have a narrow window when they will be seen active flying and visiting flowers, others are multiple brooded and several generations will be produced over the course of a spring and summer .
One of the last solitary bees to emerge is the Ivy Mining Bee which is only active in the autumn when its primary food plant Ivy is in flower.
Its therefore important to ensure that there are flowers in bloom throughout the year to support solitary bees.
Solitary bees active very early in the spring when the weather is often unsettled and changeable prefer highly rewarding flowers with high nectar content. These flowers typically have deep structures requiring longer tongues, often they hang suspended which protects the nectar from rainfall washing it away e.g. Comfrey.
Access to high quality food sources enables them to survive sudden cold or wet periods.
Unlike the Honey Bee and many of the Bumble Bees which feed from a wide variety of flowers many solitary species are specialists feeding on a few or one type of flower only. Examples include the Ivy Mining Bee Colletes hedera which feeds almost exclusively on Ivy blooms and the Davies Mining Bee (pictured right) Colletes daviesanus which is fond of Yarrow Achillea sp. And its various cultivars. These can be attracted to gardens by planting their preferred flowers. Another specialist is the mining bee Macropis europaea which collects pollen and fatty oils from the flowers of Yellow Loosestrife Lysimachia vulgaris.
In addition to being a food source several plants are very important to solitary bees as sources of nesting materials for their nests. Leafcutter and some of the Osmia bees cut and collect segments of leaves and petals to seal heir nests. Some burrowing species collect oily secretions from plants to water proof their burrows and prevent their larva from drowning.
The Wool Carder bee Anthidium manicatum collects the fibres from Stachys to line its nests—it is the only UK solitary bee that ‘carders’ its nest in this way.
Spring plants for solitary bees
Pulmonaria, Comfrey, Field Beans, Wall flower Bowles Mauve, Brassica’s, Dandelion, Blue Bell, Anenemones, Lesser Celendine, Daisy, Apple, Pear, Plum, Cherry Laurel, Cherry, Dead Nettle, Green Alkanet, Goat Willow, Bugle, Pyracantha
Summer plants for solitary bees
Marjoram, Beans, cultivated Peas, Vetches. Everlasting Pea, Campanula’s, Birds Foot Trefoil, Centaurea (both blue corn flower and perennial cornflower), Hawksbeards, Fox and Cubs, Verbascum, Heather, Stachys, Salvias, Catmints Nepeta, Oxe Eye Daisy, Poppies, Rosemary, Mints, Thyme, Thistles, Echium, Astrantia major, Echinacea, Rudbeckia, Achillea, Scabious, Rosa species.
Autumn plants for solitary bees
Ivy, Asters, Solidago
Best plants for Bumblebees
There are 24 species of Bumble bee in the UK some of which have short tongues and some which have long tongues. Only 8 species are commonly found throughout the UK, the rest are becoming increasingly scarce. Their tongue length determines which sort of flowers they prefer to forage on. When planting for Bumble bees it its important to plant a range of plants that will accommodate species with varying tongue lengths.
Among the plants most important for Bumble Bees are the legumes which include Birds Foot Trefoil, Clover’s and Vetches. Dead Nettle and other members of the Laminacea are also important particularly early in the season when Queens need to gain weight to reach breeding condition. Echium, Stachys, Scabious and Knapweeds are important in late summer followed by Thistles which are also used as mating platforms as well as a food source.
In Gardens Bumble bees will be attracted to Echinacea, Globe Thistle, Salvia’s, Dahlia’s, Cosmos and Sunflowers in Late Summer.
Trees for bees
Lime Trees Tilia sp. Are a main constituent of City honeys and give the honey a citrus, minty after taste. Much of the honey produced in London comes from Lime trees. In addition to collecting nectar from the trees flowers the bees will also collect honey dew secreted by aphids on the trees leaves. This produces a very dark treacly like honey. Flowering time: Late June / Early July. Moist soil and sultry conditions are needed to induce nectar production.
White Beam Sorbus aria and its cousin the Sweedish White Beam Sorbus intermedia are widely planted in city parks, gardens and as street trees. These medium sized trees produce masses of creamy white blooms in May and June which develop into bright red berries by autumn.
Horse Chestnut Aesculus hippocastinum originate from Continental Europe and are widely grown in towns and cities as street or parkland trees. Their blooms change colour once pollinated to inform the bees that there is no longer nectar to be had. Pollen from this tree can be identified on the bees Scopa as brick red. Flowering time: April to May.
Indian Chestnut Aesculus indica originate in the Far East put are widely planted as garden or parkland trees in cities. Very much like their relative the Horse Chestnut in appearance but with narrower glossy leaves. This tree is an important late summer source of nectar and pollen flowering at a time of year when most native trees are displaying semi ripe fruits. Flowering time: Late July through August.
Tree of Heaven Aithanthus altissima is a large tree resembling our native Ash (Fraxinus excelsior) though it is unrelated. This tree produces large bracts of Green to yellow flowers from Mid-June to Late July (roughly at the same time our lime trees bloom). In dry years when Limes yield little or no nectar this tree can become a main source for urban honeys. This tree is now on schedule 9 of the Wildlife and Countryside Act and is illegal to plant in the UK, though existing trees are permitted to remain as long as they are registered and you do not allow them to self seed - they are becoming invasive with climate change.
Acers (Maples and Sycamores) include the native Field Maple Acer campetris and the introduced Sycamour Acer speudoplatanus are visited by honey bees for their early supply of pollen and nectar. Bees may also collect honey dew from aphids feeding on Sycamore leaves. Flowering time: March to April but usually a short bloom period of just 2-3 weeks.
Willows Salix sp. Willows flower early in the year and are particularly important for bees as a source of nutritious pollen. Among the best are Goat Willows Salix caprea which include many dwarf forms suitable for small city gardens.
Cherry Prunus sp. Include many flowering trees including the native wild Cherry Prunus avium, the Bird Cherry Prunus padus and the evergreen shrub Cherry Laurel Prunus laurocerasus. These trees and large shrubs flower from early April to late May and provide both pollen and nectar. Large specimens can produce 2 litres or more of nectar per day. These plants also secrete nectar from extra-floral nectaries at the base of their leaves which honey bees will forage on after the trees have flowered. There smaller relative the Blackthorn Prunus spinosa flowers very early in the year, In London this may be as early as February/March time and is usually in bloom when it is still too cold for honey bees to work its blooms
Chinese Privet Ligustrum sinense is a large shrub or small tree related to the common hedge privet grown in domestic gardens. It is frequently planted as a small specimen tree in city parks, gardens and streets where its abundant fragrant blooms attract honey bees in their droves in Late summer. A useful late summer forage source when little else is flowering in abundance. Flowering time: July and August.
False Acacia Robina Pseudoacacia also known as Black Locust bean tree is native to the USA and was one of the first North American trees to be introduced to the UK in 1640. It is a popular source of nectar with honey bees but will only yield nectar in years when the summer is very hot and sultry. This tree grows well in poor dry soils so is well suited to life as a city street tree. The cultivar ‘Semperflorens’ is particularly useful as it flowers virtually all summer whereas the species type tends to only flower for a few weeks in June.
Tulip Poplar Liriodendron tulipifera is a large Tree native to the Eastern United States. In its native lands it is an important nectar source for bees often representing the largest potential for a good honey crop in US cities. In good growing conditions it can equal the Lime trees in value for its honey. The tree produces masses of large yellow – orange flowers in June and July. Each flower only produces nectar for a brief period, usually 24-48 hours but the sheer mass of blooms means a single tree can provide nectar for several weeks. The flowers produce large droplets of nectar at the base of the petals. Each bloom may produce an entire tea spoon of nectar. It has been estimated that a mature tree can produce 4kg of nectar per day which equates to 1kg of honey. Unfortunately in the UK our climate is not usually hot enough to encourage copious nectar production but in the city microclimate these trees can be a valuable source of nectar. They are being planted increasingly around new housing developments as street trees because of their attractive leaf shape and colourful blooms.
Indian Bean Tree Catalpa Bignoniodes is a valuable late summer nectar source when other trees have finished flowering. The large bell shaped flowers attract honey and Bumble Bees.
Honey bees will also collect nectar from extra floral nectaries on the leaf surface. Flowers: July through August.