When to plant cucumber seeds – the perfect time to ensure a bumper crop for summer salads

Knowing when to plant cucumber seeds is a key consideration if you're after optimal growth and the best harvest in time for summer. Cucumbers have long been praised by gardeners as one of the easiest plants to grow. However, as with any grow-your-own project, timing is everything.

If you've been teetering on the idea of learning how to grow cucumbers at home to enjoy as delicious additions to your salads when the season finally turns, you'll be happy to know that if you've got a greenhouse, cucumbers are actually one of the best crops you can plant in February.

However, if you're simply relying on Mother Nature, we'll tell you now that it's probably best to wait a couple more weeks before planting your cucumber seeds. 

When to plant cucumber seeds

'The best time to plant your cucumber seeds outdoors is in late spring when you are certain the last frost has passed – late April is a good time,' begins Craig Wilson, co-founder, director and in-house gardening expert at Gardeners Dream. 'Just ensure that the night time temperatures are not likely to drop below 12–15°C.'

This is because cucumbers are warm-seasoned vegetables, favouring and thriving best in warmer environments. Petar Ivanov, gardening expert at Fantastic Gardeners warns that 'planting them too early in cold sold can lead to poor germination or stunted growth.'

Craig even recommends growing your cucumbers in a cold frame in the garden come the prime time to sow in late April.

However, if you don't fancy waiting until late Spring to get started on planting your cucumbers, you can get away with getting a head start if you're a proud owner of a greenhouse. Ideally, a heated greenhouse is the best environment for planting cucumber seeds during these early winter months.

Nelly Hall, brand director at bespoke greenhouse manufacturer Alitex assures, 'Cucumber seeds can be sown as early as February for those with heated greenhouses.' Better yet, Nelly advises making the most of the space in even the smallest of greenhouses by growing cucumber up garden trellises or supports.

If you choose to go down the greenhouse route, Chris Bonnet, founder of Gardening Express recommends keeping your cucumber seeds in a 'heated greenhouse from February until March and then an unheated greenhouse to sow in April onwards.'

When the temperature and season finally change come the onset of summer, only then should you move your cucumbers out of the greenhouse so they can continue to grow successfully. 'When the sun does come out more make sure to monitor their conditions as they can become burnt if they're exposed to the heat for too long,' warns Chris.

But generally speaking, Craig assures that the key to producing a good crop is to position cucumbers in a warm, sunny spot and water them regularly.

FAQs

Do you need to support cucumber plants?

Yes, it's recommended to grow cucumbers up trellises or supports for various reasons.

'During their germination and early growth stages, it's important to provide a trellis or another type of support structure for vining varieties to save space and promote better air circulation, which will reduce the risk of disease,' explains Fantastic Gardeners' Petar Ivanov.

Can you plant cucumbers in a pot?

Yes, you can plant cucumbers in a pot. Despite being vining plants, they can still be planted in pots or containers.

How late can you plant cucumbers?

As cucumbers favour warm climates, they can be planted as late as May or June since the weather is guaranteed to be consistently warmer if you're doing it outside. 

However, as Gardening Express' Chris Bonnett cautioned earlier, just be sure to keep a close eye on them during the summer months as they can become burnt when kept in direct light for too long.

So, if you're lucky enough to have a heated greenhouse, what's stopping you from getting that head start on planting your cucumber seeds?