April

Written by Pollyanna Wilkinson

April Greenhouse Growing Guide – Pollyanna Wilkinson

April can be an unpredictable month of glorious sunshine or torrential showers, but with longer days and warming soil, it’s a key time to get going in the garden. If you’re wondering what to plant in April, the good news is there’s plenty you can sow both under cover and outdoors to set yourself up for a productive growing season.

With the warmer weather of the last few weeks you can really feel things waking up now, and there’s plenty to do to set up for the growing season ahead.

In the greenhouse

If you’re starting seeds under cover, April offers ideal conditions for a wide variety of crops. Knowing what to plant in April in greenhouses will help you make the most of the warmer days and give your seedlings a strong head start:

Tomatoes, peppers and aubergines – Start seeds in trays or modules with bottom heat if you have it. Move into larger pots as they grow.

Cucumbers, courgettes and melons – Sow in individual pots and keep warm. These will be ready to harden off and plant out in late May or early June.

Tender annuals – Zinnias, nicotiana, cosmos and scabious are all great options to plant in April under glass, giving you strong, healthy plants ready to go out after the last frost.

Salad crops – Quick-growing lettuce, rocket and oriental greens like mizuna are ideal April planting choices, especially for greenhouse sowing. These can be picked young and harvested continually throughout spring.

Basil and other herbs – If you’re thinking about what herbs to plant in April, basil is a great choice. These need warmth to germinate and grow well, so a greenhouse gives them the head start they need.

Pot on seedlings

If you’ve been sowing seeds indoors or under cover, now’s the time to check for seedlings that have developed their first true leaves.

Gently prick them out, taking care to handle them only by their leaves to avoid damaging the delicate stems, and transfer each one into a 9cm pot filled with fresh compost.

Make sure to label everything clearly so you can keep track of your varieties, and water the pots thoroughly.

This gives your young plants the room and nutrients they need to continue growing strong and healthy, ahead of hardening off later on.

By the end of the month, in milder areas where frosts have eased, you can begin planting out dahlia tubers that you might have had potted up in your greenhouse from last month. Gladioli corms can go in too—try planting in small batches over a couple of weeks to stagger flowering.

In the garden

For gardeners planning what to plant in April outdoors, this month is perfect for early maintenance and preparing beds for summer growth.

Once tulips, daffodils and other spring bulbs finish flowering, snip off the faded blooms to stop them putting energy into seed production. Leave the foliage in place, as this feeds the bulb for next year.

If you want to reuse pots, lift the bulbs with their leaves still attached and move them to a quieter spot where they can die back naturally. Any bulbs that flowered indoors can be planted out into borders too.

Divide summer-flowering perennials

While not technically planting from seed, dividing hardy perennials like phlox and geraniums is a smart way to refresh your garden beds if you’re considering what to grow in April for a longer-term impact.

Good candidates include hardy geraniums, asters, ornamental grasses and phlox. Replant divided sections straight away and water well.

Keep an eye on slugs and snails

With tender new growth appearing, slugs and snails are quick to follow.

Try using copper rings, crushed eggshells, wool pellets or grit around vulnerable plants.

Nematodes can also be used if the soil is warm enough.