Spring Blooms

Spring Wildflower Garden Checklist: 15 Jobs for March to May

Spring in a wildflower garden is never a single tidy moment. One weekend the ground is too wet to touch; the next, self-sown cornflowers are already up and the slugs have found the foxgloves. The trick is to work with the season's rhythm rather than against it: prepare in March, sow and divide through April, then plant out and keep watch in May. Here are fifteen jobs, in roughly the order they will ask for your attention.

Read the Ground Before You Dig

Before anything goes in, find out whether the soil is ready to be worked. Take a handful from a spade's depth and squeeze it. If it holds a shiny ball that smears rather than crumbles, wait a week. Digging wet clay or heavy loam destroys the structure you spent last autumn building, and it takes far longer to repair than it does to be patient.

While you wait, deal with the roots that will haunt you all summer: creeping buttercup, couch grass, bindweed. Fork them out whole, following each white strand to its end. On a wildflower bed, hand-digging beats rotovating, which chops creeping roots into pieces and brings dormant weed seed to the surface.

Where the soil is thin or hungry, spread three to five centimetres of garden compost and let the worms pull it down. Rake only the patches you intend to sow, and leave a few bare, undisturbed squares of ground for solitary bees and ground beetles.

Sowing in the Right Order

March to early April: hardy annuals

Cornfield flowers — poppies, cornflower, corn marigold, calendula — are best sown directly where they are to flower. They resent transplanting and grow fast once the soil warms. Scatter thinly, then press the seed in with a board or your palm rather than burying it; poppies need light to germinate. A dusting of fine grit over the row keeps birds off and discourages slugs.

Perennials that want a cold spell

Many meadow perennials germinate poorly from a spring sowing unless they get the cold, damp conditions they would have had outdoors over winter. Mix the seed with a little damp sand, seal it in a bag and keep it in the fridge — not the freezer — for a few weeks before sowing. Pots left outside in a sheltered corner work just as well, just more slowly. Yellow rattle is the exception: it settles best from a late-summer sowing, so if you have seed left in spring, sow it and expect patchy results.

May: plug plants and half-hardy annuals

Harden off anything raised indoors over seven to ten days, bringing plants outside by day and back in at night, extending the time gradually. Plant out once the risk of frost has passed in your area, water them in, and put a collar of grit or a cut plastic bottle around each one. Newly planted plugs are the favourite meal of every slug on the plot.

Divide and Move Perennials While Growth Is Young

Late March and April are the window for splitting summer- and autumn-flowering perennials: ox-eye daisy, yarrow, hardy geraniums, asters, monarda. Lift the clump with a fork, then prise it apart using two forks placed back to back, or slice cleanly with a spade. Replant the outer, vigorous pieces at the same depth and bin the woody middle. Water well and keep watering for a fortnight.

The same weeks are ideal for moving self-sown seedlings. Foxgloves, columbines and teasel rosettes shift easily while they are small and sulk when they are large, so lift them with a good rootball and water them in straight away.

Mulch Late, and Keep It Off the Crowns

Mulching too early traps cold, wet soil and slows everything down. Wait until growth is underway and weeds have started to appear, then spread a five-centimetre layer of well-rotted compost or leaf mould.

Keep mulch clear of stems, crowns and the necks of plants, where damp material invites rot.
Leave gaps around anything you want to self-sow — poppies, nigella and foxgloves need open soil to seed into.
Use grass clippings sparingly, in thin layers, or they mat down and smell.
Save woodchip for paths and around shrubs rather than digging it into a wildflower bed.

Walk the Beds Weekly with Your Hands

Ten minutes of looking does more than an hour of spraying. Turn leaves over, check growing tips, and look at the plants after rain, when slugs are active. Deal with aphids on soft new growth with a jet of water or your fingers; predators such as ladybirds, hoverflies and lacewings will arrive if you leave them something to eat. Some holes in leaves are the price of a garden that feeds birds and moths, so tolerate damage that is not threatening the plant.

In dry spells, watch for powdery mildew on crowded stands and improve airflow by thinning rather than reaching for a spray. Check stakes and ties before plants get tall, and firm in any clumps lifted by frost.

Hoe, Water, and Leave the Seedheads

Hoe annual weeds on a dry, sunny morning, when the seedlings shrivel within hours. Never let them set seed — one poppy head scatters more than you will want to pull next spring. Water new plantings deeply once or twice a week in dry weather rather than little and often, and water in the morning so foliage dries before night.

Leave bulb foliage for about six weeks after flowering before cutting it back, and hold off mowing a meadow until late July or August, once the flowers have dropped seed. Some seedheads are worth keeping for the birds: goldfinches work teasel, knapweed and cornflower heads long into autumn.