How to grow corn
Overview
Corn (Zea mays) is a warm-season grass grown for sweet cobs or grain. It requires full sun, steady moisture, and block planting for effective wind pollination. In Australian gardens, it performs best with warm soil and a long growing season.
Varieties
- Honey and Pearl — Popular bicolor sweet corn with good flavour and tenderness, widely adapted across Australia.
- Peaches and Cream — White and yellow bicolor variety known for its extra-sweet, creamy kernels.
- Golden Jewel — All-yellow sweet corn variety that produces reliable crops in temperate and subtropical regions.
- Torero — Hybrid sweet corn with high disease resistance and uniform cobs, suited to warmer climates.
Soil Preparation
Corn prefers well-drained, fertile soil with a pH of 5.5–7.0. Before planting, dig in plenty of well-rotted manure or compost to supply nitrogen. Ensure the soil is warm (above 15°C) for germination.
Growing Guide
Plant corn in a sunny, open position to allow wind pollination. Sow seeds directly 2-3 cm deep, 20-30 cm apart, in blocks of at least 4 rows (rows 75-90 cm apart) to ensure good pollination. For a continuous harvest, sow every 2-3 weeks. Corn is a heavy feeder, so enrich soil with compost before planting. Wait until soil temperature reaches at least 15°C before sowing.
Sowing
Sow seeds directly into warm soil at 2-3 cm depth, spacing 20-25 cm apart in rows 75-90 cm apart. Germination takes 5-10 days. Direct sowing is recommended as corn transplants poorly due to root sensitivity.
Care
Feed corn with a nitrogen-rich fertiliser when knee-high (about 30 cm) and again when tasselling. Remove weak side tillers to focus energy on main stalks. Apply a layer of organic mulch to conserve moisture and keep roots cool during hot weather.
Companion Planting
Corn grows well with beans (which fix nitrogen) and pumpkins or squash (which shade the soil and suppress weeds) – a classic three sisters planting. Avoid planting with tomatoes or celery, as they compete for nutrients.
Common Pests & Risks
Common pests include corn earworm (Helicoverpa armigera), managed with biological controls like Trichogramma wasps or Bt sprays. Birds and rats may damage cobs; use netting or reflective deterrents. In humid areas, watch for rust and smut; ensure good air circulation and avoid overhead watering.
Harvesting
Harvest corn when silks have turned brown and kernels release a milky liquid when pressed. This is typically about 20 days after silks appear. Use immediately for maximum sweetness, or blanch and freeze surplus.
In the Kitchen
Sweet corn is best enjoyed within hours of harvest, as sugars rapidly convert to starch. Boil or grill cobs whole. Surplus can be blanched and frozen. Dried kernels from dent corn or popcorn varieties can be used for polenta or popped kernels.
Troubleshooting
Poor kernel set: caused by inadequate pollination; plant in blocks of at least 4 rows. Yellow leaves: nitrogen deficiency; apply a side-dressing of nitrogen fertiliser. Lodged stalks: result of wind or excess nitrogen; hill soil around bases. Corn earworms: treat with Bt or Trichogramma wasps. Cob rot: linked to wet weather; improve spacing and air circulation.