Your April seed sowing jobs
April is one of the busiest months in the gardening calendar - Nic Wilson shares the flowers and veg to start from seed now
April is a delightful but unpredictable month. Plants can be damaged by sharp frosts or blanketed in mid-spring snow, while in other years our gardens swelter in spells of unseasonably hot weather. In warm springs, especially in milder areas, many seeds can be sown outside this month. Continue sowing cucumbers, courgettes, squashes, celeriac, celery and half-hardy annuals under cover.
More seed-sowing advice:
Sowing half-hardy annuals, such as cosmos, under cover this month makes it easy to add dazzling colour to summer borders. If you don’t have enough space indoors for pots of seeds, you can direct sow outdoors from mid-May until the end of June.
Sow half-hardy annuals in modules or pots of peat-free seed compost and place in a warm spot on a windowsill, or in a propagator, until seeds germinate. Prick out seedlings and pot on when large enough to handle. Harden plants off and transplant into the garden after the last frost.
We plant Mexican sunflowers (Tithonia rotundifolia ‘Torch’) among our perennials as a fiery orange highlight among the cool purples and blues of catmint, salvia and lavender. These vibrant annuals also attract a wealth of pollinating insects to their dahlia-like flowers.
This year I plan to sow the compact variety T. rotundifolia ‘Goldfinger’, which has warm orange flowers with yellow centres and grows to 70-100cm tall. T. rotundifolia ‘Fiesta del Sol’ is another superb compact Mexican sunflower with intense orange blooms. It thrives in a sunny spot in well-drained soil and can be grown in large containers.
Filling the garden with glorious fragrance on summer evenings, tobacco plants are a must for any scented garden. N. alata ‘Lime Green’ is one of our favourites with its zingy green tubular flowers ending in a five-pointed star. It adds freshness to arrangements and is a fantastic plant for attracting night-flying moths to the garden.
If you are growing tobacco plants to provide food for moths, choose N. alata rather than N. sylvestris whose trumpet flowers are too long for most British moths to reach the nectar. Avoid modern varieties as well, as many are not strongly scented so don’t lure in the pollinators. Tobacco plants are harmful if eaten.
Perennial wildflower meadows provide important habitats for invertebrates and other wildlife, but a colossal 7.5 million acres of meadow have been destroyed in the UK since the 1930s. To grow your own meadow, sow wildflower seeds before the end of the month, either direct in the ground or in a container to create a mini-meadow. Perennial wildflower meadows require well-drained, poor soil in full sun, but suppliers often create wildflower seed mixes for other locations and soil types, such as woodland areas and damp meadows.
To rewild your lawn, you can sow a perennial wildflower seed mix of UK provenance comprising species that occur here naturally, or individual native species that suit your soil and aspect, in plugs or trays of peat-free, multi-purpose compost. Grow seedlings on and transplant into the lawn once they are well established and able to compete with the grasses. An easier alternative is simply to stop regular mowing. It is fascinating to see what wildflowers emerge once you reduce the frequency of mowing, especially in older lawns and those that haven’t been treated with weedkiller.
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Growing your own perennials from seed gives you access to a wide range of varieties at a fraction of the cost of buying fully grown plants. Saving your own seed or sharing seed with friends can reduce the cost even further.
Choosing plants that flower in their first year, such as maiden pinks (Dianthus deltoides) and yarrow (Achillea millefolium), and sowing early this month, means you could be enjoying a blaze of colour in your borders within the next few months.
For something a bit different, try growing the sky-blue flowers of Cupid’s dart (Catananche caerulea), Maltese cross (Lychnis chalcedonica) with its intense orange blooms, or the large silvery-white evergreen leaves and yellow flower spikes of Verbascum bombyciferum ‘Arctic Summer’.
The ideal time to sow members of the cucurbit family, such as cucumbers, courgettes, squash, marrows and pumpkins, is from the beginning of this month until May and June. Squashes are easy to grow: simply sow seeds in 7.5cm pots in peat-free multi-purpose compost, at a depth of 2.5cm. Water and place in a propagator or on a sunny windowsill at 18-21°C to germinate. Harden off and plant out in the garden after the last frost. Cucurbits like to be planted in fertile, moisture-retentive soil in full sun.
Growing squash from seed gives you a wide choice of varieties. Choose from summer squash like ‘Custard White’ or winter types like ‘Crown Prince’, and from enormous pumpkins to the tiniest patty pans. Summer squashes crop between July and October, while pumpkins and winter squashes are ready to pick in the autumn.
We love to grow deep orange ‘Uchiki Kuri’ which has deliciously nutty flesh. Climbing ‘Tromboncino’ is another family favourite. Related to butternut squash, it is harvested when the pale green pendulous fruits are still young. There are no seeds in the tromboncino’s elongated neck, so each fruit yields a large amount of sweet courgette-like flesh. Patty pan squashes such as ‘Sunburst’ and ‘Greendisc’ provide bountiful harvests and we like to grow ‘Summer Mix’ so we can pick a range of different coloured fruits.
Perfect for spring and summer salads, radishes are available in a wide range of shapes, sizes and vibrant colours. These speedy croppers are ready to harvest in as little as four weeks and, though the roots are small, they pack a spicy punch. Radishes are best sown at weekly or fortnightly intervals to avoid too many maturing at the same time. They can be sown in containers, as long as plants are kept well-watered, so you can grow your own radishes even if you don’t have a garden or vegetable patch.
Radishes can also be sown in the same row, at the same time, as slow-maturing crops such as parsnips. Not only do they mark the row until the slower-growing vegetables appear, but you get two crops from the same space. Sow outdoors this month in short drills, 2.5cm apart. Make sure the ground doesn’t dry out, so that your radishes don’t become tough and woody.
We love traditional varieties like ‘French Breakfast’ with its long red and white roots, as well as bright scarlet, white-tipped ‘Sparkler’. ‘Felicia’ is another attractive radish with deep purple roots shaped liked ‘French Breakfast’. If you can’t decide which colour to pick, try ‘Rainbow Mix’ – a lucky dip of purple, red, yellow and white roots. For something completely different, ‘Rat’s Tail’ radish is grown for its edible seed pods which are harvested when immature and green.
Dwarf French beans
Now that the last frost is only a few weeks away, dwarf French beans can be sown under cover towards the end of the month, ready to plant out in late May or early June. The beauty of compact varieties is that they don’t need support and can even be grown in containers. Sow individual seeds 5cm deep in modules or 7.5cm pots of peat-free seed compost. Water and place on a sunny windowsill or in a propagator to germinate, which should take between a week and 10 days.
Dwarf French beans have a range of different-coloured pods from deep purple through green to pale yellow. ‘Purple Teepee’ has always cropped well for us and the purple-black pods (which turn green when cooked) are delicious. ‘Mistik’ is another tasty variety with attractive purple flowers and pods. It is suitable for growing in pots and window-boxes.
With tender yellow pods that mature early, ‘Polka’ also produces good harvests, and ‘Boston’ has long green pods and is ideal for growing in containers. Dwarf borlotti beans, such as ‘Firetongue’, produce beautifully marbled white and purple beans which can be dried and stored, and the red pods are an eye-catching addition to any kitchen garden.
Once April arrives, it is tempting to start sowing outside irrespective of the weather. But mid-spring can still bring cold temperatures and frosts that prevent germination and kill seedlings. Hold off until the soil has warmed sufficiently for weeds to start to appear, and be ready with cloches in case the weather takes a turn for the worse. Seeds are important resources, so by sowing some outdoors this month and keeping back-up seedlings under cover, you can avoid too much wastage.
Raising seedlings under cover also provides protection from slugs and snails until plants are large and robust enough to go out in the garden and survive the hungry attention of munching molluscs.
What else to sow in April
Vegetables: beetroot, carrot, parsnip, courgette, cucumber, climbing French beans, broad beans, runner beans, leek, Swiss chard, spinach, lettuce, kohlrabi, turnip, summer cauliflower, spring onion, celery, celeriac, sweetcorn, peas