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Gardening in Italy?→ March’s almanac for the Italian climate
ALMANAC · UK CLIMATE

The garden in March

March is the start of the busy season. The soil begins to warm, perennials push through, and there's suddenly a lot to do — pruning, dividing, sowing and feeding all at once.

The trap is the weather. A warm week in March can be followed by hard frosts well into April, so hardy plants and seeds can go out, but tender plants and seedlings still belong under cover. Work with the soil, not the calendar: if it's cold and sticky, wait.

UK and similar cool temperate climates. Last frosts in the south of England typically come in April; further north and inland, into May.

AT A GLANCE

Spotlight: dividing perennials

Many perennials slowly exhaust the soil in the middle of their clump, leaving a bare centre with flowers only around the edge. Dividing them every three to four years restores vigour and gives you new plants for nothing.

Early spring, just as new shoots appear, is ideal for late-flowering perennials such as rudbeckias, asters, heleniums, leucanthemums and daylilies. Lift the whole clump with a fork, working around it before levering it out. Small clumps can be pulled apart by hand; tough ones are split with two forks back to back, or cut with a spade or old bread knife. Keep the young, vigorous pieces from the outside, each with several shoots and a good root system, and throw away the woody centre.

Replant at the same depth in soil improved with a little compost, firm in, and water well even if the soil feels damp. Spring-flowering perennials such as bergenias and pulmonarias are better divided after flowering or in early autumn, and a few plants — peonies, hellebores, eryngiums — resent disturbance and are best left alone.

RudbeckiaShasta daisyDaylilyAsterHeuchera Propagation: division ›

Jobs this month

Borders and perennials

Perennials can be divided as soon as they show new growth. It's the best way to rejuvenate clumps that have gone bare in the middle — and to get new plants for free.

Divide congested clumps of rudbeckia, leucanthemum, hemerocallis and asters. Propagation: division › RudbeckiaShasta daisyDaylilyAster
Put supports in place for tall perennials before they need them. Staking & supporting plants › DelphiniumPeonyShasta daisy
Feed and mulch borders while the soil is moist. Mulching ›
Cut oregano and other woody herbs back to the new shoots at the base. Cutting back herbaceous perennials › OreganoThyme

Shrubs, roses and climbers

Roses and late-flowering shrubs get their last prune. Evergreens can be trimmed once the worst frosts are over, and many shrubs benefit from a spring feed.

Prune bush roses to outward-facing buds and feed them. Pruning roses (by group) › Rose
Thin old stems of oleander and hibiscus under cover, and shape them before growth. Pruning shrubs (general principles) › OleanderHibiscus
Cut back lantanas and fuchsias overwintered indoors. Pruning shrubs (general principles) › LantanaFuchsia
Feed acid-loving shrubs such as pieris, camellias and rhododendrons with ericaceous fertiliser. Feeding & NPK basics › PierisCamelliaRhododendron

Vegetables and fruit

Hardy crops can be sown outdoors once the soil reaches about 7°C — cloches help. Tender crops stay indoors for now.

Sow early peas, carrots, lettuce and beetroot under cloches or in pots. Propagation: sowing seed › PeaCarrotLettuceChard
Plant onion sets and shallots. Ornamental allium
Sow tomatoes and peppers indoors for greenhouse or outdoor crops. Sowing in trays under cover › TomatoChilli pepper
Plant first early potatoes at the end of the month in mild areas. Tomato

Houseplants wake up

With longer days, houseplants begin to grow again. This is the start of the repotting and feeding season.

Repot houseplants that are root-bound, one pot size up. Repotting houseplants ›
Start feeding again at half strength as new leaves appear. Feeding & NPK basics ›
Pot up coloured calla tubers under cover, watering sparingly. Repotting houseplants › Arum lily

Sow and plant

Sow
  • Peas, broad beans, carrots, beetroot, lettuce and spinach (under cloches)
  • Tomatoes, peppers, aubergines (indoors)
  • Rudbeckia hirta, zinnias late in the month, cosmos (indoors)
  • Sweet peas outdoors in mild areas
Plant out
  • Onion sets and shallots
  • Summer bulbs in pots under cover (lilies, gladioli)
  • Perennials and hardy shrubs from containers
  • First early potatoes in mild areas

Watch out for

Slugs and snailsYoung shoots of hostas, delphiniums and lettuces can disappear overnight.AphidsThe first colonies appear on rose shoots and tender new growth under glass.Late frostFrost after a mild spell browns magnolia flowers and pieris shoots.

Questions

Is it safe to put plants out in March?

Hardy plants, yes. Tender plants such as geraniums, dahlias, busy lizzies and citrus should stay under cover until the last frost has passed, usually from mid-May in most of the UK.

When should I start feeding the garden?

A general fertiliser in March or April as growth starts, followed by a mulch while the soil is moist, covers most borders and shrubs.

Can I divide perennials in spring?

Yes — early spring is ideal for most late-flowering perennials. Spring-flowering ones are better divided after flowering or in autumn.