What to sow outdoors in April: spring vegetables and flowers

Why April for outdoor sowing?

April is when the soil finally becomes warm enough for direct sowing. Soil temperature now hovers around 8-12 degrees Celsius, which is the minimum for many vegetables to germinate. At the same time, the risk of night frost ends in most regions around mid-May, so you still have a buffer. This makes April ideal: fast-growing vegetables are in the ground and mature by summer.

Direct sowing outdoors is cheaper than buying plants and gives you far more variety. You choose the varieties yourself, sow exactly when you want, and are not dependent on what garden centres offer. Many gardeners actually prefer direct sowing outside to indoor seed sowing because it is less work and better matches the natural growth rhythm.

Vegetables that can go directly in April

Carrots: fine seed, patience required

Carrots (Daucus carota) germinate slowly (2-3 weeks) and the seed is extremely fine. Sow in April, remove weeds (they compete with young carrots), and wait until early May for first shoots. Sow thinly in a line, then thin to 3 cm apart per plant. Varieties: 'Nantes', 'Chantenay', 'Imperator' (long). Harvest from July, 70-80 days after sowing.

Tip: mix carrot seed thinner by mixing the seed with sand, then you do not sow so densely.

Radish: lightning fast, ready in 4 weeks

Radish (Raphanus sativus) is the fastest vegetable. Sow in April and harvest in May. Types: round red-white ('Cherry Belle'), long varieties ('French Breakfast'). Sow thinly in a row, thin to 2 cm apart. Water regularly, otherwise they become peppery and full of holes. 25-30 days to maturity.

Sow radish again every two weeks, then you have fresh ones continuously.

Lettuce: light germinating, half shade possible

Lettuce (Lactuca sativa) germinates in light, so do not cover the seed after sowing. Sow directly outdoors in April in a thin line, thin to 15-20 cm apart (depending on variety). You can sow cut lettuce densely, head lettuce more spaced out. Varieties: cut lettuce ('Lollo', 'Oakleaf'), head lettuce ('Iceberg', 'Buttercrunch'), romaine ('Parris Island'). Watering is essential, since lettuce bolts when dry or hot. Harvest after 40-50 days: an April sowing gives a May-June harvest.

In full summer: sow lettuce better in July for autumn harvest, because April sowing bolts in June.

Spinach: frost-tolerant, varieties by season

Spinach (Spinacia oleracea) can go in from early April, even March if no more frost is forecast. Sow in a row, thin to 8-10 cm. Varieties: 'Matador', 'Paladin', 'Bordeaux' (with coloured veins). Spinach is frost-tolerant, but it grows slowly below 10 degrees. Harvest after 45-50 days: an April sowing gives leaves to cut or a whole plant to harvest in May-June.

Tip: sow spinach again in June-July for autumn harvest.

Beans: soak in warm water first

You can sow beans (Phaseolus vulgaris) in April, but if the soil is still cold they rot. Soak the seeds in warm water (around 20 degrees) overnight for better germination. Spacing: beans at 20-30 cm intervals, 2-3 seeds per hole. Varieties: shelling beans ('Borlotto'), snap beans ('Cobra'), runner beans ('Blauwhilde'). Fast growth (60 days), harvest in July.

Wait until mid-April or early May to be safe against night frost killing the seedlings.

Onion and garlic: less common from seed

You can grow onions (Allium cepa) from seed (heirloom varieties such as 'Ailsa Craig'), but this gives smaller bulbs than sets. Sow in April in rows, thin to 8 cm. Many gardeners buy sets instead. You do not sow garlic (Allium sativum) from seed, you plant cloves in October.

Annual flowers direct sown

Many annual flowers grow perfectly from direct sowing outdoors in April:

Sunflower (Helianthus annuus): sow seed thickly in April, cover lightly, thin to 30 cm. Fast growing, 60-80 days to bloom. Varieties: dwarf ('Teddy Bear'), tall ('Russian Giant').

Cosmos (Cosmos bipinnatus): sow thinly in April, do not cover, press lightly. Bloom 60-70 days. Great for cut flowers.

Poppy (Papaver rhoeas): direct sow in April, press lightly, do not cover. Modest-growing flower, 40-50 days to bloom.

Marigold (Tagetes patula): sow thinly in April, half shade is fine, water regularly. The strong scent keeps aphids away. Bloom 50-60 days.

Zinnia (Zinnia elegans): sow only once the soil is at least 18 degrees, April in southern regions, May further north. Slow to germinate, but the long bloom of 60-70 days makes the wait worthwhile.

Sweet pea (Lathyrus odoratus): sow in March-April, soaking the seed in warm water helps germination, provide support for the stems. Bloom 70-90 days.

Not sure which colour combination of these annuals suits your border? At gardenworld.app you can see them combined first in a preview of your own garden.

Soil temperature: the key to success

Many sowings fail because the soil is still too cold. Carrots, beans, squash and courgettes need at least 12 degrees to germinate. Spinach and lettuce already germinate from around 5 degrees. April feels warm, but the soil below 10 cm depth can still be 5-8 degrees.

Check it: insert a soil thermometer 5 cm deep and wait two minutes. If it is colder than 10 degrees, wait another week. Have you worked in compost? That warms the soil a bit faster.

Tip: lay black plastic mulch over the bed two weeks before sowing, it catches the sun and warms the soil.

Sowing technique: thinning is crucial

Many gardeners sow too thickly. You think: more seed = more chances. Truth: dense sowing leads to weak plants competing with each other.

Carrots: sow thinly in a line (2-3 seed per cm), thin after first leaf to 3 cm apart. Radish: sow thinly in a line, thin to 2 cm. Lettuce: sow thinly, thin to 15-20 cm (cut lettuce denser than head lettuce). Beans: sow individual seed in holes, 30 cm apart, one plant per hole. Sunflower: sow 3-4 seed per hole, thin to one strong plant.

Thinning must be done as soon as the first true leaf is visible. Snip the weak seedling off at soil level rather than pulling it, because pulling often lifts the roots of the plant next to it as well.

Sowing under fleece

Fleece (a thin, breathable fabric) covers sown rows and warms the soil. This advances germination by 1-2 weeks. Sow normally, lay the fleece over the row and secure the corners with soil or pegs. Leave the fleece on until the plants are big enough or pollinating insects need to reach the flowers, then remove it. Advantage: faster results. Disadvantage: extra work and checking.

Vegetables under fleece: carrots, radish, lettuce, spinach, beans, squash.

Step-by-step guide

Step 1: Prepare soil

Weed out weeds, dig soil and break clumps fine. Add compost, 2 cm layer. Mix soil and compost well.

Step 2: Draw straight rows

Stretch a string between two pegs and draw a straight line in the soil with a rake or spade. Rows 20-30 cm apart, depending on the type.

Step 3: Sow the seed

Sow thinly for fine seed (carrot), thicker for coarse seed (beans). Check the seed packet for the right depth and cover lightly with soil or seed sand.

Step 4: Water and wait for germination

Spray gently with a garden hose or watering can, moist but not waterlogged. Then wait for the first shoots: carrots after 2 weeks, radish after 5 days, lettuce after 1 week.

Step 5: Thin

As soon as the first true leaf is visible: remove the weak seedlings and leave the strong ones.

Step 6: Maintenance

Water every 2-3 days, more often in summer. Weed between the rows.

Frequently asked questions

Can I sow directly outdoors if the soil is still wet after rain?

No, wait until the soil feels crumbly. Sowing in wet, compacted soil creates a crust that the seed cannot push through. Check it this way: grab a handful of soil and squeeze it shut. If the clump falls apart again by itself, the soil is ready for sowing.

My seed is not germinating, what is wrong?

Three causes: the soil is too cold (wait a week), the seed is too old (bought more than two or three years ago), or it was sown too deep. Rule of thumb: sow about twice as deep as the seed is large. Carrot seed: on the surface or at 2 mm depth. Beans: 2-3 cm deep.

How much seed do I need per row?

That depends on the seed: sow fine seed such as carrot and lettuce thinly, and coarser seed such as beans and squash a bit thicker. The seed packet usually gives a guideline, for example "sow thinly in rows 30 cm apart". As a rule of thumb, aim for 2 to 3 seeds per centimetre along the row.

What do I sow if frost threatens in April?

Spinach, lettuce, radish and carrots tolerate light night frost down to around -2 to -4 degrees, spinach can handle a little more. Beans, squash and courgettes are frost-sensitive, so wait until after mid-May. Annual flowers are frost-sensitive as seedlings but harden off as they grow.

April sowing date per variety

Early April: spinach, lettuce, radish (frost-tolerant). Mid-April: carrots, onion, radish second sowing. Late April: beans (if soil above 12 degrees), annual flowers (sunflower, poppy, marigold). After mid-May frost danger: squash, courgette, melon (frost-sensitive).

Annual flower sowing date per variety

Late April: sunflower, poppy, cosmos, sweet pea (soak in warm water). May: zinnia (soil above 18 degrees), marigold (warm). May-June: morning glory (Ipomoea), nasturtium (Tropaeolum majus).

See how your garden looks

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