How to grow corn

What you need to know about corn

Name: corn, sweet corn (Zea mays varieties).

Plant type: annual vegetable.

Height: less than 1m to 2m+, depending on variety.

Foliage: long, to 50cm, strappy leaves, generally an attractive semi-glossy deep green. Base of leaves wraps around the stem.

Climate: tropical and sub-tropical, warm and cold temperate.

Soil: prefers quality, rich soil but will grow in most soil types.

Position: full sun, tolerates wind.

Flowering and fruiting: flowers towards late summer when planted in spring. Cobs ripen 4–6 weeks after flowering.

Feeding: must be planted in improved soil and fed well for best performance.

Watering: reliable moisture brings best results.

Appearance and characteristics of corn

If you can meet a few basic requirements, corn can be one of the easiest and most rewarding vegies you can grow. You’re almost guaranteed a fantastic harvest of a couple of cobs per plant.

A fast-growing annual, corn is generally tall, thin and always a single-stemmed plant. It’s technically a grass, as it’s in the family Poaceae, and you can see this in the way its leaf bases clasp the stem. In fact, the leaves are shaped like giant grass blades. The leaves can reach around 50cm in length, but will only be around 5–8cm wide. They are quite a rich green, and have visible veins running lengthways along them. Corn’s handsome leaves and bulk makes it quite attractive in the vegie garden.

Aerial or support roots often form around the base of the stem as the plant ages. A single plant should produce between two and four cobs of corn.

Corn is self-pollinating, with male and female flowers appearing on the same plant. Male flowers will arise at the top of the plant and produce masses of pollen; female flowers, which will become the cobs, appear in the junction of the leaf stem and stalk.

Uses for corn

Generally, corn is a big plant, and quite fast-growing, making for dramatic, seemingly rapid growth. It’s also a useful plant in the vegie garden. It makes a very handsome backdrop plant and, because it’s wind tolerant and dense, it can be planted as a windbreak for softer herbs or vegies. It’s a great one to grow with the kids, too, as they can measure its growth every few days and always see something happening.

How to plant and grow corn

Corn grows best in full sun. It is tolerant of windy conditions when planted in groups, but individual plants will be easily broken by wind.

Corn is tolerant of virtually any soil type, but the best growth comes in quality soil that has been improved with the addition of compost or well-composted manure. In sandy soils, such organic matter must be added to improve moisture retention. Avoid overly damp positions.

When to plant corn

In warm temperate regions, corn will be planted in late winter to early spring. In cold temperate it will be planted in mid to late spring. In tropical regions it can be grown year-round, and in all but the coldest months in the sub-tropics.

When to harvest corn

Corn takes around 120 days from seed to harvest. If grown from seedlings, this can be reduced to around 90–110 days.

Planting tips

1. Improve soil with quality compost or well-composted manure at planting time.
2. Add blood and bone and a controlled-release fertiliser at planting time, or use an organically fortified controlled-release fertiliser.
3. Corn is very wind-tolerant when planted en masse, but it’s best to plant it in groups, not rows, as this will provide more support.
4. If planting from seedlings, these can be planted with around one-third of the stem section beneath the first leaves below ground, as roots will develop from the stem.
5. If planting from seed, drop a couple of kernels in each hole.
6. As plants develop, mulch well with a fast breakdown organic product such as lucerne or pea straw.

Corn seedlings

Corn will grow very well in pots; just ensure you select a dwarf variety, and that the pot is large enough that the plant won’t become top-heavy. Use a premium organic potting mix or a vegie and herb blend.

Corn is one of the few seedlings that can benefit from being planted deeper than it was growing in its pot. As it has dormant roots within the stem, planting it with a centimetre or so of the seedling stem below the soil will actually improve its establishment and speed of growth.

Caring for corn

Corn requires little if any maintenance once it starts growing. Ensure adequate moisture is provided at all times, especially as the cobs are developing. Regular application of a liquid organic product such as a seaweed tonic will help with plant vigour.

Corn harvest

One of the biggest points of confusion regarding corn is when to harvest the cobs.

• The cobs will be ready around 4–6 weeks after pollination.
• Corn does not continue to ripen once picked so it must be picked ripe and eaten fresh, preferably the day it was harvested.
• Peel back the leaves at the tip of the husk to expose the first few kernels. For sweet yellow varieties, the kernels should be firm, golden yellow and plump. If they are, use a pin or the tip of a sharp knife to prick a kernel or two. If milky juice comes out, the cobs are ripe.
• Unripe kernels will be soft, overripe will be hard.
• Harvest early morning for the sweetest cobs. This is because the plant’s normal processes convert sugars to starch during the day before reversing this overnight.

Diseases and pests

Corn is relatively pest-free. The major problem comes from various grubs that can enter the cob and damage kernels. You can avoid this by regularly checking developing cobs for evidence of caterpillars.

How to propagate corn

As an annual plant, corn will be grown from seed or planted from seedlings.

Safety tip

After applying fertiliser, delay harvesting for a few days and rinse well before cooking and eating. If using products to deal with pests, diseases or weeds, always read the label, follow the instructions carefully and wear suitable protective equipment. Store all garden chemicals out of the reach of children and pets.

If you like this then try

Lettuce: expand your vegie garden with this easy-to-grow, year-round favourite.

How to plant and grow herbs: keep it fresh in the kitchen by growing all the herbs you need.

Lemon tree: easy and enjoyable to grow, lemons make a great addition to your edible garden.

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