A growing year, under glass.Practical advice for UK gardeners
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April in the greenhouse

Seed trays fill quickly now. Leave enough space between pots for light and air, and avoid sowing more than you can grow on.

UK seasonal guidance · Reviewed September 2026

Start with your conditions. Dates are a guide. Northern and exposed gardens can be several weeks behind sheltered southern ones. A greenhouse without heat does not guarantee frost protection.
01

Sow

Sow cucumbers indoors towards mid or late spring; follow the seed packet for your variety. Sow basil in warmth and repeat lettuce sowings.

02

Grow

Pot tomatoes into larger pots as roots fill the old ones. Begin hardening off hardy plants destined for outdoors on suitable days.

03

Harvest

Harvest radishes promptly while tender, and pick baby salad leaves from established plants.

04

Jobs this month

Fit crop supports before planting. Check vents and irrigation equipment, and monitor temperature every day.

Make your own growing notes

Record what you sowed, your overnight minimum temperature and how the plants responded. Check the compost below the surface before watering: the same calendar date can bring very different conditions from one year to the next. Use the seed packet’s variety-specific guidance alongside this monthly plan.

For tender crops, distinguish the warmth needed for germination from the conditions needed after seedlings emerge. For winter leaves, choose varieties intended for the season and allow for slower growth as daylight falls.

Further reading: RHS greenhouse vegetable growing.

GROWERS’ NOTES

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FURTHER READING

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Explore useful books with reading levels, practical notes and links back to our growing guides.

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