What to Plant in Your UK Garden This March

What to Plant in March

March sits at the edge of winter and spring, which means you can do far more than most gardeners realise. Overnight frosts are still possible — especially in the North — but daytime soil temperatures are creeping up, and many plants actively benefit from a cool start.

Early Spring Bulbs (plant now for summer colour)

If you missed autumn bulb planting, gladioli, dahlias and begonias can all go in March — either directly into beds (South UK) or started in pots indoors to transplant once frosts pass. Alliums planted in March will establish quickly and flower by June.

• Gladioli — plant corms 10–15cm deep from mid-March southwards. Stagger planting every 2 weeks for a long flowering season.
• Dahlia tubers — start in pots under cover now; harden off and plant out after last frost (mid-April south, mid-May north).
• Allium 'Purple Sensation' — go in now if you haven't planted; still enough time to get flowers in June.

Hardy Perennials to Plant in March

Hardy perennials bought as bare-root or pot-grown plants can go straight into borders from March. The cool, moist soil helps roots establish before the plant puts energy into above-ground growth.

• Achillea (yarrow) — thrives in any well-drained soil. Flowers June–September. Drought-tolerant once established.
• Astrantia — beautiful in shade or part-shade. Long-flowering, pest-resistant, and deer-proof.
• Geranium 'Rozanne' — the UK's best-selling perennial for a reason. Flowers continuously May–October. Sun or part-shade.
• Nepeta (catmint) — plant now for June blooms. Cut back after first flush for a second wave in August.
• Salvia nemorosa — plant in a sunny border for rich violet spires from May onwards.

Shrubs to Plant in March

March is excellent for planting shrubs. Soil moisture is high, temperatures are mild, and the plant has the whole growing season ahead of it to establish. Bare-root shrubs are still available and considerably cheaper than pot-grown.

• Roses — bare-root roses can still be planted through March. Feed with rose fertiliser after planting.
• Lavender — plant in early March in free-draining soil or raised beds. South-facing aspects only.
• Hydrangea — plant in a sheltered spot with morning sun. Water well during first year.
• Actinidia kolomikta — a fast-growing climber with spectacular pink-tipped variegated leaves. Plant against a sunny wall.

Tips by Soil Type

UK soil varies enormously — and the wrong plant in the wrong soil is one of the most common causes of garden failure. Here's what to prioritise based on what's underfoot.

Not sure what soil you have? Dig down 30cm and squeeze a handful. Clay holds its shape, sandy falls apart, loam forms a shape but crumbles when pressed, chalk shows white streaks. Or upload a photo of your garden to Selfseed and we'll infer it from your postcode's geological data.

Tips by Light Level

Light is the single biggest factor in plant selection. A sunny-spot plant in deep shade will limp along and rarely flower. Get this right first.

North vs South UK: Frost Dates & Timing

The UK spans nearly 1,000km from tip to toe, and planting timing varies significantly. The difference between Cornwall and the Scottish Highlands can be 4–6 weeks in practical planting terms.

General rule: if your ground has had frost in the last 10 days, hold off planting anything labelled 'frost tender'. A chilled plant that survives a frost will sulk for weeks. Patience saves money.

Microclimate Matters

Your regional frost date is a guide, not a guarantee. Sheltered south-facing urban gardens can be 2°C warmer than the official local average. Exposed hillside plots can be 3°C colder. If in doubt, observe: when forsythia is fully open in your street, your last hard frost is likely behind you.

Month-by-Month Planting Calendar: March to June

A clear timeline for what to do when — covering ornamentals, shrubs and some key edibles.

10 Quick March Gardening Tips

1. Cut back ornamental grasses now — before new growth emerges. Leave about 10cm above the crown. Do not cut in autumn.
2. Feed borders with a balanced fertiliser — a single application of slow-release granules in March feeds plants through spring and into summer.
3. Divide congested perennials — clumps of achillea, hemerocallis and geranium that flowered poorly last year should be lifted and divided now.
4. Mulch now, not later — apply a 5–8cm layer of compost or bark mulch before plants get too tall. It locks in winter moisture and suppresses weeds.
5. Start dahlias early indoors — you'll get larger plants with more tubers by next autumn if you start in March pots rather than direct planting in May.
6. Prune roses — cut hybrid teas and floribundas to an outward-facing bud, removing any dead or crossing stems. Mid-March is ideal for most of the UK.
7. Sow hardy annuals direct — cornflowers, californian poppies and nigella can be scattered directly into prepared soil from mid-March southwards.
8. Water newly planted shrubs — even in March, a dry spell can stress new plantings. Keep a close eye for the first 6 weeks.
9. Check bare-root plants in storage — if you heeled-in bare-root roses or hedging over winter, plant them out before growth starts in earnest.
10. Visit your local RHS garden — Wisley, Harlow Carr, Hyde Hall and Rosemoor are all bursting into colour from mid-March. It's the best inspiration and free plant-hunting research you can do.

Want to see example planting plans? Browse the Selfseed gallery →