Tips on how gardeners can help conserve bee populations - plus, find out what else needs doing in the garden this week.

By Hannah Stephenson

Reports that our bee population is at crisis point as numbers have been hit by bad weather and particularly long winters should prompt responsible gardeners to protect our bees by creating a prosperous environment for them.

Last year's annual survey by the British Beekeepers Association (BBKA) indicated an increase in losses of honey bees and the organisation is concerned that losses may be even greater this year if the long winter is anything to go by.

"Much longer winters mean that bees are potentially running out of stores," says Gill Maclean, BBKA spokeswoman.

"We don't yet know what the losses will be for this year but we are concerned that they are going to be greater than they were last year."

Weather-related impacts such as cold spells affect colony development and queen-mating. Honey bees don't forage in very cold or wet weather, so their winter stores were depleted last year.

The honey bee is the only bee to maintain a colony throughout the winter, reducing its colony size in autumn and relying on its stores of honey to last it through the winter months when it is too cold for foraging or there is no forage available. Some colonies may have since been lost simply by running out of stores.

However, gardeners can do their bit to help bees, says Maclean.

"Planting the right sort of plant is important and try to plant in drifts. There are so many bee-friendly plants including thyme, oregano, mint and viburnum. Plant some trees for bees as well, including spring-flowering cherries, apples, plums and pears."

All blossoms are widely visited by bees including blackthorn, cherry, plum, damson and crab apple. Other trees that are widely visited are the horse chestnut for its nectar and sycamore for its pollen.

She also advises gardeners to set aside part of the garden as a decorative wildflower area which will be a magnet for bees, planting white and red clover, borage, thyme, bugle and other bee-friendly plants.

"Bees also need water, so you can do something like fill a pot lid with water and put stones in it and netting over it so that they can drink without falling in."

Gardeners should make sure they provide a succession of bee-friendly plants which will flower between February and November, to give bees the best chance of building up their stores.

Last year, the Royal Horticultural Society (RHS) launched a guide as part of its Perfect for Pollinators initiative, listing more than 200 wildflowers, such as corncockle, teasel and wild parsnip, that provide plentiful pollen and nectar for pollinating insects.

It advises gardeners to: :: Avoid plants with double or multi-petalled flowers, which may lack nectar and pollen, or insects may have difficulty in gaining access.

:: Never use pesticides on plants when they are in flower.

:: Where appropriate, British wild flowers can be an attractive addition to planting schemes and may help support a wider range of pollinating insects.

:: Observe the plants in your garden. If you know of plants with blooms that regularly attract insects, let the RHS know.

:: Choose flowers that bloom successively over the spring, summer and fall, such as coreopsis, Russian sage or germander, in order to provide pollen and nectar resources to the native bees of all seasons.

:: Encourage bees by keeping honey bees yourself or allowing a beekeeper to place hives in your garden. Nest boxes containing cardboard tubes or hollow plant stems, or holes drilled in blocks of wood will provide nest sites for some species of solitary bees. Such nests are available from garden centres or you can make your own (holes/tubes should be in a mixture of sizes with a diameter of 2mm-8mm). Place these nest sites in sunny positions. Some solitary bees nest in the ground, either in bare soil or short turf. They will find their own nest sites, so tolerate the small mounds of soil deposited by the female bees when they excavate their nest tunnels.

:: Provide nest sites for bumblebees: Bumblebee nest boxes can be purchased but they are often ignored by queen bumblebees. They prefer to find their own nest sites down tunnels dug by mice or in grass tussocks. The tree bumblebee, Bombus hypnorum, has recently colonised in Britain and will often use bird nest boxes :: If you want to become a beekeeper, details of county beekeepers' associations and training courses can be seen on www.bbka.org.uk Best of the bunch - Pieris This beautiful shrub which thrives in acid soil looks fantastic at this time of year, when the new leaves on its dense, evergreen foliage turn bright red, then pink and creamy white, and it produces long sprays of blooms which look like lily-of-the-valley.

It needs little attention, other than to be planted in ericaceous compost, but prefers shade from the morning sun.

Among the most popular varieties are P. floribunda 'Forest Flame, while if you want something slightly different, there's a white and green-leaved variety called P. japonica 'Variegata'.

Pieris are ideal shrubs for an acidic woodland settings or in large pots of ericaceous compost.

Good enough to eat - Coriander It's one of my favourite herbs, used to dress many Asian dishes or adding flavour to salsas, fiery dips and salads.

It needs to be sown in rows or patio containers every six weeks or so from late spring to mid-summer to ensure a long harvest, or on the kitchen windowsill for fresh leaves all year round.

If you're just growing leaf coriander, sow from late April onwards in a sunny, sheltered position in well-drained soil, in a place which will be partially shaded during the hottest part of the day to allow the leaves to retain their flavour.

Coriander doesn't transplant well, so sow it where you want it to grow. Seeds should be sown half a centimetre deep and then thinned slightly, although with leaf coriander you only have to do this if they're very overcrowded, and water them sparingly.

When the plants are 15cm high, cut the leaves, repeating this every month. If you want the seeds, you'll need to sow by May and thin the plants more, as to get a good crop of seeds the plant doesn't like to be crowded.

Good leaf varieties include 'Cilantro' and 'Leisure', which can be grown as a cut-and-come-again crop, keeping them around 10cm (4in) tall, while 'Moroccan' is good for seeds.

Three ways to... Beat weeds 1. As tiny seedlings appear, hoe every week or two, preferably on a dry, sunny day, leaving the weed seedlings to shrivel in the sun.

2. If you weed when the annual weeds are bigger, dig them out individually, clearing them away afterwards or they'll root back into the soil.

3. With tough, perennial weeds such as ground elder or bindweed, either use a systemic weedkiller, based on glyphosate, painted or sprayed on the offending plants on a dry day, which is absorbed through the leaves and slowly kills the roots. Wait a few weeks to see if regrowth appears and if it does, treat them again. If you are a committed organic gardener and don't want to use weedkiller, re-visit the offending weeds each week, removing all top growth, which will weaken and eventually kill them.

What to do this week :: Put new aquatic plants in the pond, either in the soil at the bottom or using special aquatic baskets.

:: Earth up early potatoes.

:: Keep planting vegetables into the ground and under glass for a succession of crops.

:: Harden off aubergines which have been raised under glass, planting out under cloches and working a little general fertiliser into the bed beforehand.

:: Pinch out badly placed shoots on pruned rose bushes.

:: Plant crocosmia, galtonia, gladioli and nerine.

:: Net blackcurrants against birds.

:: Start pruning trained fruit tree forms, such as espaliers, fans and cordons, to encourage fruit bud formation :: Plant evergreens and shift large specimens if necessary.

:: Remove cloches from strawberries during the day to allow access by pollinating insects.

:: Protect crops from carrot fly.

:: Prune Clematis montana after flowering.

:: Sow fast-maturing and late-flowering annuals directly into their flowering positions.