Seeds to sow now:

Indoors or in a heated greenhouse

Coriander

Cress

Cucumber

Forget-me-not

Ornamental pepper

Tomato

Outside

Alyssum

Amaranthus

Antwerp hollyhock, Fig-leaved hollyhock, Hollyhock

Aster

Aubretia, Rock cress, Aubrieta, Aubrietia

Basil

Beet, Beetroot, Chard

Beetroot

Beetroot, Garden beet

Borecole, Kale

Bristly hollyhock

Broccoli

Cabbage

Candytuft

Cardoon

Carrot

Cauliflower

Celery

Common hollyhock

Cornflower

Courgette

Delphinium

French bean, Fine bean

Hollyhock

Italian beetroot, Beetroot, Garden beet

Kohl rabi

Lettuce

Love-in-a-mist

Marrow

Nasturtium

Normandy sorrel

Ornamental winter kale

Radish

Runner bean

Spinach

Spinach, Summer spinach

Spring onion

Sweet pea

Sweetcorn

Swiss chard, Ruby chard, Rhubard chard

Turnip

Outside under cover

Cucumber

Sweetcorn

Shows and events:

I have checked the events listed below and have added comments where necessary. Please check the show website before travelling, as some events are very popular and the venues may have put restrictions in place, others might have to be cancelled at the last minute.

All event details have been entered as accurately as possible, but please check with the event organisers before travelling to avoid disappointment.

The UKGardening web site has been running since 1998. The idea behind the site has always been to provide what we think will be interesting and useful information for the novice gardener.

Jobs to do in the garden this week.

• As daffodils fade, remove the flower heads. Don't cut back the leaves - leave them to die back naturally. However if you want to tidy them up, wait until the leaves have yellowed before removing.
• Now is the best time to plant lavender. Widely grown for its scent and foliage, lavender is ideal for borders or a low hedge. Available in shades of purple, blue, white and pink it is a magnet for bees and butterflies
• Postion plant supports where they will be needed in late summer. Doing this now reduces the risk of damaging the roots later in the season.
• Plant maincrop potatoes in prepared ground or potato growbags.
• As summer-flowering herbaceous perennials start to come back to life, lift and divide overgrown plants.
• Plant onion sets (bulbs). Run a string line across the bed and plant the bulbs, 5-10cm (2-4in) apart, up to their necks so just the tips are showing. Space the rows 25-30cm (10-15in). Firm the soil around them and water well, cover with a cloche for added protection. Keep an eye on them until they get established as some birds like to pull the sets out.
• Begin regular cutting of your lawn. If the grass is long increase the height adjustment of the mower to the highest setting. Once this first cut has been done, lower the blades/deck and go back over the lawn.
• Clean the leaves of smooth leaved house plants. Wipe large leaves such as those found on rubber plants, swiss cheese plants and umberella plants, with a damp cloth. Smaller leaved plants can be dipped in a bowl of clean water. Do not attempt to wash the leaves of 'hairy' leaved plants such as African violets, use a soft brush such as a paint brush or a used toothbrush.
• Remove algae and moss from patios and paths with a pressure washer or proprietary patio and path cleaner (traditionally a tar oil winter wash could have been used, but these are no longer available, particualrly to the amateur gardener, as they were found to be carcinogenic).
• May is an ideal time to create ponds / pools. Click here to see the pond project page.
• Spray roses with 'Rose Clear' to kill aphids and protect from blackspot.
• If becoming boisterous, prune spring-flowering clematis including alpina and macropetala after flowering. Use cuttings to propagate new plants.
• Thin out seedlings, leaving the strongest growing plants. Water the soil gently beforehand to reduce soil disturbance.
• Replant outside in the border any dahlia tubers which were lifted and stored over winter. Put a stake in the ground during planting to reduce the chance of damaging the plant and roots once it has started growing.
• Dead head azaleas and rhododendrons.
• Introduce fish into a new pond.
• If your daffodils, in the past, have been attacked by the narcissus bulb fly (Merodon equestris - the larvae will eat the centre of the bulb), firm down the soil around the bulbs or use fleece or similar to cover daffodil bulbs to stop female flies from laying eggs, preventing their larvae causing damage. Derris powder was traditionally used as a treatment, but it is no longer available (Derris powder contains high levels of the rotenone, which is a strong insecticide, toxic to fish, it has also been linked to Parkinson's disease. All derris based products have been withdrawn from sale in the UK from October 2009) and chemical alternatives aren't available.
• Once forced bulbs have finished flowering, plant them out into the garden.
• Remove any wayward growing raspberry shoots. They will just crowd the fruiting canes.
• If your lawn is more moss than grass, then treat with a lawn moss killer. Bare in mind that the moss will turn black within a couple of days, so don't be too alarmed. A couple of weeks after application, if you are left with bare patches in your lawn, mix equal quantities of grass seed and seived compost and scatter over the patches, cover areas with fine netting or twigs gently pushed into the soil, to protect from birds and animals. Combination lawn feed and moss killer is available, but feeding your lawn when it's not necessary will encourage it to grow quicker and therefore need to be cut more regularly.
• Scatter growmore granules under fruit trees and bushes, especially apple, pear and plum trees. If it doesn't rain for a couple of days, water the granules in with a hose or watering can. Growmore is a slow release, general fertiliser, it includes the three main plant nutrients (nitrogen, phosphates and potassium).
• Some perennials appreciate a late May prune, known as the Chelsea Chop (as it's done around the same time as the famous flower show) encouraging stronger and stockier plants often with an extended flowering period. Cut stems back by a third or a half. Plants that benefit include penstemon, hardy chrysanthemums, tall sedums, helenium and echinacea.
• Transplant any self-set aquilegia, lupins and hollyhocks to new locations.
• As it's starting to warm up, it's a good time to lay a new lawn, although the best time is in Autumn or late winter, as it's damper and cooler, allowing the turf to bed in without you having to worry too much about regular watering. See here: laying a new lawn for further information.
• Prune helichrysum and artemisias shrubs to encourage bushy plants.
• Prune spring-flowering shrubs, including ceanothus and forsythia, after they have bloomed. Give topiary a light trim after a spurt in spring growth.
• Support herbaceous border plants with canes, where they will be needed in late summer. It's easier to do this now while the plants are still small, this also reduces the risk of damaging the roots later in the season.
• Pots, planters and hanging baskets can be planted up now, although keep them covered at night until all chance of frost has passed. See the hanging basket project for further information.
• Prune plum trees, paint fresh cuts with Arbrex to prevent infection.
• Fuchias flower from the ends of their branches, nipping out the growing tip will encourage more shoots, creating a bushier plant with more flowers.
• Remove the dead heads of spring flowering bulbs, such as tulips and daffodils, before they have a chance to produce seed. This will encourage the plant to store energy in the bulb rather than wasting it on seed production.
• Control weeds in lawns with a selective weedkiller. Don't cut the grass for at least a week after applying. Don't put these grass cuttings on the compost heap.
• Cut runners from strawberries (unless trying to propagate more plants). Runners will divert energy away from crop production.
• Earth up the first early potatoes that were planted in March, to stop the tubers being exposed to light, turning green.
• Your pond may have started to turn green and cloudy. This is due to a rapid increase in algae, which flourish in the warmer spring temperatures. Once the pond plants start to grow again, especially the oxygenating plants, these will use up the nutrients and create shade, reducing the amount of algae. To speed up the clearing of the water, drop a small string bag/pair of old tights stuffed with barley straw, into the pond. Weigh the straw down, so that it floats just below the surface of the water.

  As the straw breaks down, it produces hydrogen peroxide, which reduces and inhibits the growth of algae and blanket weed. If the algae is particularly bad, barley straw extract can be bought in liquid form and added to the pond water (follow the instructions on the bottle, but as a guide before purchasing,125ml treats approximately 4,500 litres/1,000 gallons, but multiple, fortnightly treatments through the year may be necessary). If you have a fountain or waterfall, try to position the barley straw underneath this. Remove and replace the barley with new straw after about six months, before it completely rots down, polluting the water.

  The small, pre-filled barley straw bags to add to your pond, cost about £2 each, but you can buy a 17 litre pack, which will last a few years for about £10 from your local pet shop or Amazon here: Supreme Petfoods Tiny Friends Farm Russell & Gerty Barley Straw, 17 Litres

• Plant out greenhouse grown runner beans or sow them at the base of wigwams 5cm (2in) deep. Keep well watered.
• Sow vegetable seeds (courgette, marrow, runner and French beans) in the vegetable patch and salad seeds (lettuce, spring onion and radish) little and often to provide a staggered harvest through the summer.
• Remove spring bedding plants and lift and store spring flowering bulbs (with the exception of snowdrops).
• Lots of tender plants can be grown outside in containers between May and September as long as the pot is big enough and they get enough water and the occasional feed.
• Buy plants in strips or trays that are compact and sturdy, the compost that they are growing in should be moist. Try to buy plants in bud, with few open blooms.
• Paint shading on the greenhouse glass, or use shading to lessen the scorching effect of the sun and to keep temperatures lower.
• Trim hedges to encourage the branches to thicken up and to keep them neat and tidy.
• Propagate marginal pond plants. Take short cuttings, remove lower leaves and push stems into pots of mud. Keep top of the pots just under the surface of the water.
• Sow hardy annuals in their flowering positions to fill any gaps in the border.
• Check gooseberries for sawfly. Prune this year's growth back to 4-5 leaves (this shouldn't affect fruit as they appear on old wood).
• Pinch out the growing tips of annuals and some perennials to create a stockier plant and to encourage more flowers More information here.
• Spread compost from the compost bin over the borders and vegetable patch. This adds valuable nutrients to the soil and acts as a mulch, to retain moisture and reduce weed growth. The ground should be weed free and the soil moist before adding a layer of compost or mulch.
• Check the ties on climbers, flower stems and standard roses - the tops of plants can get very heavy when in full bloom or when wet.
• Take soft wood cuttings from thyme. Thyme cuttings take easily, so they can be stuck in the soil or in pots. Remember that thyme likes full sun and hates to be grown in the shade.
• Feed established roses every other week with a rose fertilizer. Deadhead regularly to encourage further flowering. Check for aphids and black spot and treat accordingly.
• Apply a weed and feed to established lawns. Water in with a hose after a few days if it hasn't rained.
• Stake and tie perennials to prevent them being broken by wind and rain. Remove fading delphinium flowers to encourage a second flowering.
• The adult vine weevil, the number one garden pest, will be emerging from the soil as the temperatures rise.
• Protect plants from slugs and snails with slug pellets, course grit or traps. Alternatively try to encourage birds, hedgehogs and frogs to your garden - all prey on slugs and snails. More suggestions to reduce slug and snail damage.
• Cover strawberries and fruit bushes with netting to protect them from birds. Start to feed the plants weekly when the fruit starts to form.
• To reduce the chance of introducing infection when pruning or deadheading, wipe the blades of secateurs, loppers and snips with a rag soaked with a garden disinfectant, such as Jeyes fluid, which can also be used to wipe down garden tables and chairs.
• Regularly water trees and shrubs that were planted last autumn and winter. Their roots won't have had a chance to fully develop yet.
• Cut grass weekly, long grass takes more nutrients out of the soil. It is also harder to cut and may leave yellow patches in the lawn.
• Continually nip out side shoots from upright (cordon) tomato plants. These reduce the amount of food available to fruit baring branches. If growing plants in the greenhouse, nip out the growing tip after the plant has produced 4-5 fruiting trusses, reduce this to 3-4 if growing tomatoes outside. See here for more information : https://www.youtube.com/watch?v=zFBgCBaFSnk&ab_channel=UKGardening
• Lift, divide and replant chives.

Recent articles:

• Creating a compost heap
• YouTube: Propagating snowdrops (Galanthus) by bulb division
• Sowing seeds
• How to lay a new lawn
• UKGardening YouTube Channel
• Tweets by UKGardening.
• Removing large branches
• Updated photo gallery