This guide forms part of our month-by-month allotment planting calendar.
March is when the allotment finally wakes up. The soil starts to warm, the days get longer, and you can properly begin the year’s sowing. It’s still early spring, so conditions vary, but there’s plenty you can start directly outdoors — and even more you can raise under cover.
Below is a clear, practical list of what to sow and plant in March on a UK allotment, without overcomplicating it.
What You Can Sow Outdoors in March
March is the first month where the soil is usually workable. If it crumbles rather than sticks, you're good to go.
Carrots
Early varieties (like ‘Nantes’ or ‘Early Scarlet’) can go straight in.
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Sow thinly to avoid heavy thinning later.
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Ideal for no-dig beds.
Parsnips
March is the perfect time — they need the long season.
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Only sow fresh seed; old seed barely germinates.
Beetroot
Reliable and easy.
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‘Boltardy’ handles cooler spring weather well.
Broad Beans
If you didn’t autumn-sow them, now’s your moment.
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Choose hardy varieties like ‘Aquadulce Claudia’.
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Sow in double rows for stability.
Onions (Sets)
Sets establish faster than seeds this early.
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Push them in so the tips sit just above soil level.
Peas
Early peas (e.g. ‘Meteor’, ‘Kelvedon Wonder’).
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Protect from mice — they’ll dig them up overnight.
Spinach & Chard
Both cope with cooler ground and germinate well.
Salad Leaves
Mixed cut-and-come-again leaves are reliable in March.
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Great for intercropping between slower veg.
What to Sow Indoors or Under Cover in March
March is prime time for undercover sowing. A windowsill, greenhouse, cold frame or polytunnel makes all the difference.
Tomatoes
If you’re growing them, start them now.
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Don’t sow too early without enough light.
Chillies & Peppers
Earlier is better — they need the longest season you can give them.
Courgettes & Squash (Late March)
Sow from the latter half of the month to avoid leggy plants.
Cabbages, Kale, Broccoli (Brassicas)
Sow in modules for planting out in April/May.
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Modules avoid root disturbance and reduce slug losses.
Leeks
Sow into deep modules or a small tray.
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You’ll plant them out in early summer.
Herbs
Parsley, coriander, basil (if under good warmth/light).
What You Can Plant Out in March
These are crops you sowed earlier or bought as young plants.
Broad Bean Seedlings
If started indoors in Feb, they’ll be ready now.
Garlic (Late Cases)
If winter was too wet, you can still plant garlic cloves in early March.
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They’ll be smaller but still worth it.
Rhubarb Crowns
Get them in the ground before they break dormancy.
Jobs to Do in March
A few smart early-season tasks will set the whole year up properly.
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Prepare beds — compost, weed, mulch paths.
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Warm the soil with fleece or cloches where you plan early sowings.
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Set up supports for peas and broad beans now, not later.
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Clean tools and disinfect seed trays.
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Start your rotation plan in the Allotment Planner so you’re not guessing later.
How to Plan Your March Sowing Properly
March is busy — and it’s easy to overdo it. Before you fill every bed:
1. Map your beds and spacing
Dragging crops onto your digital plot stops overcrowding — a classic beginner mistake.
2. Plan your rotation
Brassicas, legumes, roots, potatoes — they all need different beds each year.
The tool makes it obvious where everything should go.
3. Stagger your sowings
Don’t sow an entire packet of carrots or beetroot in one go.
Sow every 2–3 weeks for continuous harvests.
4. Track what you’ve sown
Once it’s in the ground, mark it in the planner so you know what’s where and what’s next.