How to Grow Sweet Corn

Who doesn’t love a cob of fresh sweetcorn? It’s a staple on many family tables and with a high fibre content, it aids digestion and may even decrease health risks such as type 2 diabetes, bowel cancer, heart disease, and strokes. A good source of folate or Vitamin B9, it’s ideal for pregnant women. It also contains Vitamins C and B6, potassium, niacin, protein, and antioxidants.

A little-known fact about sweetcorn is that it is a type of grass, a grain, and a fruit!

When to grow sweetcorn

Sweetcorn is a summer crop that germinates when soil temperatures reach 16-35°C or 60–95°F. It grows best when the air temperatures are 20-30°C (68–86°F). For most of us, that means the ideal time to plant is spring or early summer and in tropical regions you may be able to grow it all year round.

Sweetcorn varieties

There are hundreds of different varieties of corn – not all of them are sweet like most of us are used to though, so you want to be selective about which ones you choose. Here are a few of the common sweet varieties to consider:

· Max F1 – a hybrid variety, with yellow kernels and a sweet flavour – ideal for cooler climates and disease resistance.

· Golden Bantam – an early cropping, heirloom variety with yellow kernels and good flavour – a popular choice in Australia

· Anasazi – an ancient variety with multicoloured red, blue, and white cobs which is drought resistant

· Bicolor F1 – a hybrid variety with gold and cream coloured kernels that are super sweet

· Jolly Roger – an Australian heirloom variety with yellow kernels and sweet flavour

How to grow sweetcorn from seeds

Sweetcorn can be direct sowed or planted in seedling trays and transplanted once established. Starting in seedling trays can help to avoid gaps in your planting due to poor germination and help you ensure you are planting only the healthiest of seedlings.

Location is an important consideration. Corn likes a lot of sun and has shallow roots which can make the plant unstable so it’s a good idea to choose an area that is sheltered from the wind, so your tall plants don’t fall over when it’s blowing a gale outside. You’ll also want to ensure that the soil has good drainage and plenty of organic matter.

Sweetcorn tends to prefer soil that isn’t freshly fertilised and does well in soil that has had the fertiliser applied and then left to rest for several weeks. This helps to avoid having “leggy” plants that are less stable.

Sow the seeds around 20mm or around three quarters of an inch deep and around 30cm or 12 inches apart creating a block rather than a row. Corn needs good pollination to ensure that you get cobs full of big juicy kernels. Water in the seeds and keep the soil moist but not wet. Seedlings will begin to emerge around 5-14 days after planting.

How to grow sweetcorn from seedlings

Use the same preparation as mentioned above and plant your seedlings fairly deep using the spacing mentioned above. This will help give your sweetcorn stalks a bit more stability. Lightly water the seedling in with a seaweed solution such as the Plant Doctor’s Seaweed Secrets (use SSME10 for 10% off your order) to minimise transplant shock.

Due to its shallow roots, sweetcorn needs to be watered very consistently to prevent the roots from drying out which can impact the quality of your corn cobs.

When your cobs start forming, keep an eye out for the earworm caterpillar which is a known pest. Signs of an infestation are droppings around the top of the silk that is coming out of the top of the cob. If you see this, you can harvest the corn early and salvage what’s left of the cob. These caterpillars can do big damage to your crop, so you want to be vigilant in looking for them.

If your plants are looking pale green and a bit sad, it may be an idea to fertilise them lightly but don’t overfertilise as that can also have negative impacts on your crop.

How long does sweetcorn take to grow?

Most varieties of sweetcorn will take around 70-100 days or 10-12 weeks to reach full maturity depending on the variety.

When to harvest sweetcorn

When you see the silks browned off, that’s a good indication that your corn may be ready but to check for sure, peel back the outer husk to look at the cob. Also check out Mark’s top tips below for a surefire way to know when your corn is ready to harvest.

The cobs will last up to 2 weeks on the plants (provided the pests don’t get to them) so if you want to, you can just harvest what you need each time for the freshest corn.

If you want to grow corn next season from your own seeds, you can leave a few cobs to dry on the plants and then use them as seeds for your next crop. Heirloom varieties are best for this, as hybrid varieties usually don’t grow the same in subsequent seasons. Remember that once your corn is finished, the dried stalks make a great mulch for your garden bed or fruit trees, as they are full of nitrogen.

Mark’s top tips for growing sweetcorn

Overripe corn is awful. So, once the cobs swell and develop, keep checking/testing regularly to ensure they are perfectly ripe. This is usually when the kernels are properly formed and ooze a milky rather than clear liquid when squeezed.

You may also want to check out Mark’s videos for more tips: “5 Top Tips How to Grow a TON of Sweecorn in One Raised Garden Bed or Container” “What Happens When You Grow Corn in Winter?”

How did you go growing sweetcorn?

Mark and the Self Sufficient Me team love hearing about your growing success so leave a comment and a photo below to let us know how you went growing sweetcorn.

If you had some trouble growing sweetcorn or simply want to pick Mark’s brain about your self-sufficiency goals or projects, you may want to consider becoming a patreon for exclusive content and email access for less than a restaurant meal each month!