Greenly

How to grow Corn

Zea mays · Maize, Sweet corn

A tall, warm-season cereal crop grown for its sweet kernels. It is wind-pollinated and requires a block planting for best yields.

Corn
Photo: Forest and Kim Starr, CC BY 3.0 us, Wikimedia Commons

Quick facts

TypeVegetable
FamilyPoaceae
LightFull sun
Soil pH5.8–7
Frostdoes not tolerate frost
Soil for sowingfrom 12 °C
Germination7 days
Sowing to harvest90 days
Where it growsGreenhouse, Open ground

When to plant

Sow straight into the bed after your last spring frost, once the soil has warmed.

In an unheated greenhouse everything moves about three weeks earlier.

The first harvest comes about 90 days after the shoots appear.

Care

Greenhouse

StageWateringTemperatureFeeding
Growthevery 3 days15…28 °Cnitrogen, 14 days into the stage; nitrogen, 28 days into the stage
Floweringevery 2 days18…30 °Cbalanced (NPK), at the start of the stage
Fruitingevery 2 days18…30 °Cpotassium, at the start of the stage

Open ground

StageWateringTemperatureFeeding
Growthevery 4 days12…28 °Cnitrogen, 21 days into the stage; nitrogen, 42 days into the stage
Floweringevery 3 days15…30 °Cbalanced (NPK), at the start of the stage
Fruitingevery 3 days15…30 °Cpotassium, at the start of the stage

Growing notes

Light

Full sun is essential for stalk strength and ear development.

Soil

Rich, loamy soil with high organic matter; prefers well-draining soil that retains moisture.

Care

Plant in blocks rather than long rows to ensure wind pollination of the silks. Keep soil consistently moist during the tasseling and silking stages. Apply nitrogen-rich fertilizer early in the growth cycle to support rapid height gain.

How to tell it is ripe

  • Silks at the tip of the ear have turned brown and dry while the husk is still green.
  • Kernels are plump and smooth and fill the ear right to the tip.
  • Peel back a little husk and press a kernel with a thumbnail: milky juice means ready, watery means too early, a doughy paste means over-mature.
  • The unhusked ear feels firm and full in the hand.
  • Twist the ear downward and pull it off in the cool early morning and eat it soon; leave popcorn types on the plant until the cobs dry.

Pests and diseases of Corn

  • Wireworms

Sources

Figures cited from these sources.

  1. extension.illinois.edu/gardening/corn
  2. rhs.org.uk/vegetables/sweetcorn/grow-your-own
  3. hgic.clemson.edu/factsheet/harvesting-vegetables/