Growing sweet corn can be a lot of fun for the whole family, as there is nothing sweeter than corn on the cob, straight from the garden to the barbie. Corn, also known as maize, is one of the world’s most popular grains. High in fibre, it’s a rich source of vitamins A, B1 and B3, as well as containing minerals such as potassium and manganese.

Sweet corn can be found in a wide range of foods, from cereals such as Corn Flakes, to snack foods such as tortillas and taco shells. Enjoy sweet corn on the cob or cut from the cob to enjoy served cold in salads or salsa, or warm in casseroles, soups or as an accompaniment grilled, boiled or steamed to any meat or fish.

Sweet corn is easy to grow as long as you give it plenty of space and protection from the wind. On average, it will take 60 to 100 days to harvest depending, on the temperature and the sunshine.

Follow our seven easy steps to a successful sweet corn harvest including tips along the way.

Seven handy tips on how to grow yummy sweet corn

When to plant and location.

When to plant.

Sweet corn likes a warm, frost-free growing period, so seed is sown during spring and summer with harvests from summer plantings extending into autumn. The season ends as the weather cools, especially when there is frost. Check hardware and garden centres for varieties in your local area.

In cool to cold zones, plant sweet corn in October and November.
In temperate zones plant sweet corn from September to December, although it may still be possible until January, depending on the season.
In the subtropics, plant sweet corn from October to March so that crops mature before winter.
In tropical zones, plant sweet corn from February to May so that crops mature before the wet season.

Location.

Sweet corn prefers full sun (or with light afternoon shade in hotter climates) and protected from strong winds that can damage the plants.
Select a space with enough room to sow several rows to form a block of corn. An area 1m x 1m is the minimum space for planting.
As this is a tall crop, which takes many months to reach harvest, the space around these plants can be used to grow other crops. Before the plants become tall, it is possible to grow a quick crop of lettuce between rows or around a block of corn.
The stems can also be used to support other plants including climbing beans. A block of corn can also be grown to provide shade and shelter to other crops such as leafy greens.

Soil.

Get the soil right to harvest a bumper crop of yummy sweet corn.

Follow our steps for easy soil preparation.

Sweet corn likes a well-drained, slightly acid to neutral pH soil around 6.5 to 7. They will grow in most soils, however, hate heavy clay.
As sweet corn requires a lot of nutrients for healthy, tall growth, add plenty of compost and aged manure to the soil before planting or apply Seasol Liquid Compost.
A soil rich in nutrients helps build strong plants so add Seasol Plant + Soil Booster (100g per square metre) and a fertiliser such as PowerFeed Controlled Release Tomatoes & Vegetables.
Water in well and let the soil rest for a week or two if possible.
Spreading organic mulch around the base of the plant helps to keep the roots cool and the soil moist.

Step 1 – Sowing seeds.

Just before sowing water the soil well so the seed is sown into damp, but not overly wet, soil.
Allow plenty of room for sweet corn to grow. Not only does it grow tall, but it’s also best grown in a block at least a metre square. This is because sweet corn is wind-pollinated so planting it in a block maximises pollination and produces well-filled cobs.
Sweet corn seed is large and easy to handle. It is best sown, directly where it is to grow.
To sow seeds, make a furrow in the soil about 25mm deep. Make furrows around 50cm apart in a block of at least 1m square. Space seeds around 15-20cm apart and lightly cover after sowing.
Water in well with Seasol GOLD or Seasol as this will help to increase seed germination rates.

Note: Above image is not sweet corn seeds, it’s just an illustration to show seeds being planted

Step 2 – Germination.

Expect germination in 6-10 days. Germination may be slower in cold conditions. If the weather does turn cold after sowing seeds, the soil can be warmed up by covering it with black plastic, horticulture fleece or shade cloth. Remember to remove it during the warmer part of the day and reapply at night until the temperature increases.
Check the soil daily, if it remains damp no further watering may be needed until seeds germinate. In dry conditions, water gently.
Apply Seasol GOLD or Seasol weekly (mix 30mL of concentrate per 9 litres of water) as this will help to stimulate a strong tap root and healthy, tall growth.
When sweet corn seeds sprout, they only have two leaves. These seedling leaves are narrow and unlike the adult leaves.

Step 3 – Baby sweet corn seedlings.

About two weeks after the seed leaves have opened, the true leaves will appear; these leaves will look like blades of grass.
Thin plants when they are large enough to handle, so they are 20-30cm apart to allow plenty of room for these large plants to develop.
Spread a thin layer of organic mulch around the developing plants to retain soil moisture and reduce weed competition.
Sweet corn seedlings need a lot of nutrients to grow to produce a tasty bumper crop so, liquid feed with PowerFeed PRO SERIES for Tomatoes & Vegetables every 1 to 2 weeks. Increase the application rates from 20mL to 50mL of concentrate per 9 litres of water as the plants mature.
Check soil moisture daily and water as needed.

Step 4 – Sweet corn seedlings ready for transplant.

Transplant seedlings purchased or sown in punnets.
Plant them at the depth they were in the punnet. Soak the punnet in Seasol before transplanting to make it easier to separate individual seedlings without damage to their root system and to reduce transplant shock.
If the seedlings look a bit leggy and stretched, plant them a little deeper.
Water your newly transplanted seedlings in with Seasol or Seasol GOLD to get them over transplant shock.
Mulching around each plant suppresses weeds and helps retain soil moisture.
If extra crops are planted in and around sweet corn, provide extra water and nutrients to keep your sweet corn growing strongly.

Step 5 – Sweet corn qrowth.

The key to a good crop of sweet corn is providing the growing plants with plenty of fertiliser and regular, deep watering.
Every 6-8 weeks give another application of PowerFeed Controlled Release for Tomatoes & Vegetables to produce a bumper crop of yummy, sweet corn and to revitalise depleted soils. Remember to water it in thoroughly after application.
As the tall stems develop, they may produce roots above the ground. Build a layer of soil around these to prevent them from drying out.
Remove weeds and top up mulch.

Step 6 – Sweet corn cob formation.

Apply PowerFeed PRO SERIES for Tomatoes & Vegetables weekly as the tassels (male flowers) appear as the plant reaches maturity and begins to flower.
Tassels are produced at the top of the plant. Pollen is released by tassels and blown on the wind to fertilise the female flowers, which grow lower down on the stalk and form cobs.
Sweet corn demands a lot of water. However, it is important to keep the cobs dry as they mature, so water only the roots and avoid watering the foliage and developing cobs.
Check soil moisture daily to ensure the plant and cobs don’t dry out. Check plants morning and evening during high summer or when it is dry and windy.

Step 7 – Sweet corn ripening and harvest.

Sweet corn takes around 10 to 12 weeks to grow and produce cobs
Watch the crop carefully to pick cobs at their peak ripeness when they are sweet and juicy. Overripe cobs quickly become tough as sugars in the kernel are converted to starch.
Tell-tale signs that the cobs are ready to harvest include the silks turning from greeny-yellow to brown and cobs standing out at an angle from the side of the plant. To further test for ripeness, peel back the outer husk and press a thumbnail into a kernel. If it is at its peak, it will exude a creamy juice known as ‘milk’.
Sweet corn is best eaten as soon as it is harvested. Cobs store for a few days if they are well wrapped and kept in the crisper section of the fridge. Excess can be blanched and frozen or used to make pickles and relish.

Things to watch for…

Corn aphids Black aphids may attack corn particularly in mild autumn conditions. If numbers build up, hose them off.
Corn earworm This caterpillar appears as the cobs begin to form. Corn earworm (also called budworm caterpillars), burrow down from the top of the cob into the kernels. This pest has become resistant to most chemicals. For organic control check plants regularly for signs of caterpillars or frass (droppings) and webbing at the top of the cob. Remove caterpillars or affected cobs and spray with EarthCare Natural Pyrethrum insect spray.
Fall army worm This striped caterpillar is a new pest to Australia that may affect all mainland Australia especially during summer. It feeds on leaves and moves to cobs and is active through the warmest parts of the year. Control is difficult as the pest is resistant to many common chemicals including pyrethrum.
Leaf blight of corn This bacterial disease may attack foliage leaving brown patches. It may also lead to poor cob development. It is mainly seen in wet summers. There are no chemicals registered for control in home garden so keep foliage dry by watering the roots and also regularly remove weeds.
Sweet corn rust This fungal disease leaves rusty patches on leaves and reduces cob size and yield. Keep foliage dry by watering the roots and also regularly remove weeds. Look for rust-resistant varieties.