The complete sowing guide for March — indoor starts, outdoor direct sowing, regional timing, and the crops that will define your 2026 growing season.
Plan every month with the UK vegetable planting calendar.
Sow Indoors
Tomatoes, peppers, aubergines, celery, celeriac, leeks (last chance), onions (last chance), summer cabbages, Brussels sprouts, early lettuce
Sow Outdoors
Early peas, broad beans, carrots (under cloches), parsnips, spinach, lettuce (under cloches), radishes, spring onions
Plant Outdoors
Shallots, garlic (last chance), onion sets, early potatoes (from mid-month in south), Jerusalem artichokes, asparagus crowns
Harvest Now
Purple sprouting broccoli, kale, leeks, parsnips, forced rhubarb, overwintered salads
What to Sow in March
Tomatoes (Indoors)
March is the main tomato sowing month for most UK gardeners. Sow in a heated propagator at 18–22°C. Transplant into 7.5cm pots once seedlings have two true leaves. Keep in the warmest, brightest spot available — a south-facing windowsill or heated greenhouse is ideal. Do not plant outside until late May at the earliest.
Peppers and Aubergines (Indoors)
Both need warmth to thrive. Sow in a heated propagator at 21–25°C; germination is slow (up to 21 days). Pot on into 7.5cm pots once large enough to handle. Peppers and aubergines need to stay under glass or in a polytunnel for the whole UK season — they don't have enough time to ripen outdoors in most regions.
Carrots (Under Cloches or Fleece)
From mid-March in the south, carrots can be direct sown outdoors under cloches or fleece. Sow thinly in drills 1cm deep. Soil temperature needs to be at least 7°C — use a soil thermometer rather than guessing. Uncovered outdoor sowings are best left until April in most regions. See our when to plant carrots UK guide for full timing.
Parsnips (Direct Sow)
Parsnips are one of the few crops that genuinely benefits from early direct sowing — but only once the soil reaches 7°C. Sow thinly, 1cm deep, in rows 30cm apart. Germination can take up to 3 weeks. Use fresh seed every year — parsnip seed loses viability quickly and old seed is the most common cause of failure.
Peas (Outdoors)
From mid-March in milder areas, early pea varieties can be sown directly outdoors in a sheltered spot. Sow 5cm deep and 7.5cm apart in double rows. Protect with netting against birds, which will eat young pea shoots. See our when to plant peas UK guide.
Brassicas — Summer Cabbage and Brussels Sprouts (Indoors)
Sow summer cabbage and Brussels sprouts in trays or modules indoors in March. Both need a long growing season. Keep at 13–16°C. Transplant after hardening off in May or June. Brussels sprouts sown in March will be ready from October onwards.
Lettuce and Salad Leaves (Indoors or Under Cloches)
Fast-growing cut-and-come-again salad mixes can be sown from March under cloches or indoors. Sow thinly in shallow drills or scatter across the surface of a pot. First outdoor harvests are possible from late April with cloche protection.
What to Plant in March
Potatoes — First Earlies
First early potatoes can be planted from mid-March in southern England once the soil has warmed and the worst frost risk has passed. In northern England and Scotland, wait until April. Chit seed potatoes for 4–6 weeks beforehand by placing them rose-end up in egg boxes in a cool, bright, frost-free place. See our when to plant potatoes UK guide for variety timing.
Onion Sets and Shallots
Onion sets and shallots planted in March establish quickly and reduce the risk of bolting that can affect very early plantings. Push sets into well-prepared soil with the tip just above the surface, 10cm apart. Birds often dislodge freshly planted sets — protect with mesh or fleece for the first two weeks.
Garlic — Spring Planting (Last Chance)
Spring-planted garlic goes in from February to March. March is the last realistic opportunity for spring garlic — cloves need cold stratification to develop properly, and planting too late produces smaller bulbs. Split the bulb into individual cloves, plant 15cm apart, tip just below the surface.
Asparagus Crowns
Asparagus crowns are best planted in March or April when the soil is workable. Dig a trench 30cm deep and 30cm wide, spread the crown roots over a central ridge, and cover with 5cm of soil. Do not harvest in the first two years — allow the crowns to establish. Asparagus is a 20-year investment but one of the most rewarding perennials in the UK kitchen garden.
What to Harvest in March
- Purple sprouting broccoli — peak season; harvest shoots regularly to keep the plant producing
- Kale — still producing well; pick outer leaves before plants start to bolt
- Leeks — last of the season; harvest all remaining before they bolt in April
- Parsnips — at their absolute sweetest after winter frosts; lift before ground warms and they resume growth
- Forced rhubarb — final stems available; remove forcing pot once crowns show signs of leaf growth
Key March Tasks
- Prepare beds by forking in well-rotted compost or manure
- Apply a top dressing of a general fertiliser (blood, fish, and bone) to beds before planting
- Check for slugs and snails, which become active from March — set up traps and barriers now before seedlings go out
- Continue chitting seed potatoes in a light, frost-free place
- Cut back autumn-planted garlic: remove any mulch and weed around the emerging shoots
- Protect early-sown outdoor crops with fleece or cloches when frost is forecast
Plan Your Entire Growing Season
Month-by-month sowing schedules, 40+ crop guides, companion planting charts, and harvest trackers — all calibrated for UK conditions.
Get the UK Garden Planner →Frequently Asked Questions
What vegetables can I plant outside in March in the UK?
From mid-March in the south: early potatoes, onion sets, shallots, garlic (last chance), early peas, broad beans, and asparagus crowns. In northern England and Scotland, wait for April for most outdoor planting. Use cloches or fleece to extend the range of what you can sow outdoors in March.
When can I start sowing carrots in the UK?
From mid-March under cloches in the south, or from April outdoors without protection once soil reaches 7°C. Carrot germination requires at least 7°C soil temperature — sowing too early into cold soil results in poor germination and slow establishment.
Should I sow tomatoes in March?
Yes — March is the main tomato sowing month for most UK gardeners. Use a heated propagator at 18–22°C. Sowing earlier without adequate heat and light produces leggy, weak seedlings. March sown tomatoes planted out in late May will give a full season of harvest from July to October.
What To Plant In March UK
In March, UK gardeners can sow carrots, beetroot, spinach, lettuce, peas, broad beans, radishes, spring onions and early herbs. You can start tomatoes, peppers, aubergines, leeks, onions, brassicas, lettuce, courgettes later in the month and herbs under cover, plant out onion sets, shallots, early potatoes in mild areas, broad bean plants and hardy lettuce, and harvest overwintered leeks, kale, chard, sprouting broccoli, spring greens and protected salads.
| March task | Good UK options | Notes |
|---|---|---|
| Sow outdoors | Carrots, beetroot, spinach, lettuce, peas, broad beans, radishes, spring onions and early herbs. | Check soil moisture and local frost risk before sowing. |
| Seeds to start indoors or under cover | Tomatoes, peppers, aubergines, leeks, onions, brassicas, lettuce, courgettes later in the month and herbs. | Protected sowings help you control temperature, pests and watering. |
| Vegetables to plant out | Onion sets, shallots, early potatoes in mild areas, broad bean plants and hardy lettuce. | Water transplants well and protect young plants where weather or pests are likely. |
| What to harvest | Overwintered leeks, kale, chard, sprouting broccoli, spring greens and protected salads. | Harvest little and often, then record what clears space for the next crop. |
Vegetables to sow outdoors in March
Sow carrots, beetroot, spinach, lettuce, peas, broad beans, radishes, spring onions and early herbs. Use small repeat sowings where possible so the harvest is easier to manage and gaps do not sit empty.
Seeds to start indoors or under cover
Start tomatoes, peppers, aubergines, leeks, onions, brassicas, lettuce, courgettes later in the month and herbs under cover. This is useful when outdoor conditions are too cold, too dry, too exposed or too pest-prone for reliable germination.
Vegetables to plant out
Plant out onion sets, shallots, early potatoes in mild areas, broad bean plants and hardy lettuce. Match the planting window to your local weather and give new plants enough water while roots establish.
What to harvest in March
Harvest overwintered leeks, kale, chard, sprouting broccoli, spring greens and protected salads. Keep notes on what performed well so next year's plan is based on your own garden rather than memory.
Jobs for the vegetable garden in March
Prepare seed beds, protect early sowings, chit and plant first early potatoes where suitable, and harden off hardy seedlings gradually.
Common mistakes in March
Avoid planting tender crops outside before frost risk eases, sowing into compacted soil and skipping slug protection for seedlings.
Printable monthly checklist
For March, write down four columns: sow outdoors, start under cover, plant out and harvest. Add one line for weather notes, one for bed space, and one for the next crop so the month turns into a practical plan.
Related UK planting guides
Use the vegetable planting calendar UK, compare what to plant in February UK and what to plant in April UK, then check when to plant potatoes UK, how to grow radishes UK and seed starting tools UK.
FAQ section
What vegetables can I plant in March in the UK?
In March, UK gardeners can sow carrots, beetroot, spinach, lettuce, peas, broad beans, radishes, spring onions and early herbs. You can start tomatoes, peppers, aubergines, leeks, onions, brassicas, lettuce, courgettes later in the month and herbs under cover, plant out onion sets, shallots, early potatoes in mild areas, broad bean plants and hardy lettuce, and harvest overwintered leeks, kale, chard, sprouting broccoli, spring greens and protected salads.
What seeds can I sow outdoors in March?
In March, outdoor options include carrots, beetroot, spinach, lettuce, peas, broad beans, radishes, spring onions and early herbs. Adjust the list for your local soil, weather, frost risk and available protection.
What seeds can I sow outside in March UK?
In workable soil, March outdoor sowings can include carrots, beetroot, spinach, lettuce, peas, broad beans, radishes and spring onions, with protection in colder areas.
Turn This Month's Jobs Into A Plan
Month-by-month advice works best when it becomes a written sowing list, bed plan, and follow-up task list.
Plan the next step
Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.