Sweetcorn is a rewarding crop to grow, whether you're a seasoned gardener or a beginner. With its tall, impressive stalks and sweet, tender cobs, it's hard not to feel a sense of pride when harvesting your own.
This guide will take you through everything you need to know about how to grow sweetcorn successfully.
When is best to grow sweetcorn?
Ideal planting times
Sweetcorn is a warm-season crop, so timing is key. You can start sowing indoors or in a polytunnel in early spring and transplant outdoors in late May or early June once the soil has warmed.
Variety-specific considerations
The variety of sweetcorn influences how long it takes to grow. Early-season varieties like Earlibird are perfect for cooler climates or those who want an earlier harvest.
Mid and late-season varieties, such as Lark or Conqueror, take longer and are ideal if you have a longer growing season or want to extend your harvest into autumn.
How long does sweetcorn take to grow?
Depending on the climate and the variety you choose, growing sweetcorn can take two to four months. The extended warmth and humidity in a
polytunnel can speed up growth, so you might be able to harvest a little earlier than you would by growing outside.
How do you grow sweetcorn?
Growing sweetcorn requires a little attention to detail but it's well worth the effort. The key factors to keep in mind are soil preparation, temperature, watering and feeding.
Preparing the soil
Sweetcorn is a heavy feeder, so you'll need to enrich the soil before planting. Add well-rotted manure or compost to improve soil fertility and structure. Make sure it drains well too. Polytunnels also help the soil warm up more quickly, which is essential for sweetcorn to thrive.
Watering and feeding
Aim to keep the soil consistently moist but not waterlogged, and use a balanced fertiliser every few weeks to provide the nutrients sweetcorn needs for healthy growth.
How do you go sweetcorn from seeds?
Starting sweetcorn from seeds is easy and gives you a head start on the growing season.
- Sow: Start seeds in small pots or trays from mid-April to early May. Use a good-quality seed compost and sow singly just below the surface.
- Keep warm: Place the pots in a warm spot (ideally 18-21°C), such as a polytunnel, to aid germination.
- Water gently: Keep the compost moist but not waterlogged to help the seeds sprout.
- Harden off: About a week before transplanting outdoors, harden off your seedlings by placing them outside for a few hours each day.
How far apart do you plant sweetcorn?
Plant sweetcorn at least 30cm apart in a large 4x4 or 5x5 block. Using a grid formation rather than rows allows the wind to more effectively pollinate the plants, leading to better yields.
How do you grow sweetcorn in pots?
If you're short on space, you can grow sweetcorn in pots. However, this requires a little more care.
- Choose large pots: Select pots that are 30cm wide and 30cm deep to give the roots plenty of space.
- Use quality compost: Fill the pots with a mix of good compost and some slow-release fertiliser.
- Sow seeds: Plant four seeds per pot. Ensure they are roughly 10-15cm apart.
- Water and feed regularly: Keep the soil moist and feed every few weeks with a balanced fertiliser.
- Provide support: As the plants grow tall, they may need staking to stop them from toppling over. Alternatively, choose a shorter variety to grow.
Growing in pots allows you to move your plants to the sunniest spot and helps protect them from pests. However, pots can dry out quickly, so keep an eye on watering.
When is the time to harvest sweetcorn?
Sweetcorn is ready to harvest when the tassels at the top of the cob turn brown and the kernels inside are plump and milky when you press them.
Harvest your sweetcorn in the morning when it's cool. This helps preserve the natural sugars and moisture, ensuring the sweetest, juiciest cobs.
Provide your sweetcorn with the perfect home with Premier Polytunnels
Growing sweetcorn in a polytunnel offers numerous benefits. Not only does it protect your plants from unpredictable weather and pests but it also extends your growing season. You can start early, provide a controlled environment and harvest when the conditions are just right.
Call us on 01282 811250 or email
info@premierpolytunnels.co.uk if you'd like to speak to one of our experts about our range of
polytunnels and
accessories. Be sure to check out our other
growing guides for additional inspiration.