Corn

The best sweet corn is picked for fresh eating. There is also popcorn, flour corn and ornamental corn. Corn must be planted in blocks to allow for good wind pollination. However, corn works well interplanted with beans and squash (the “3 sisters”). It can also provide shade in the heat of the summer for salad greens.

Site Requirements

Corn requires full sun, at least 6 hours of direct sun, and moist, well‐drained soil. Prepare the planting area by mixing 3‐4” of composted manure, lime and cottonseed or fish meal (3#/100 sq ft.) into the top 6‐10” of the soil.

Planting

Corn thrives in warm weather and is best planted outdoors May through June when soil temperatures are in the 60s. You can start seeds indoors in late April through May, 1‐2 weeks before desired transplanting date. Corn roots dislike disturbance so try to avoid pot bound plants.

If your transplants have multiple stalks leave the root ball intact and pinch extra stalks so you are left with one or two seedlings.

When soil temperatures are in the 60s, corn can be direct seeded. Plant seeds outdoors 1” deep, 4” apart, in 6‐8” deep rows. Cover seeds with a tin layer of soil or compost. Seedlings or seeds should be planted in blocks of at least 2‐6 rows of 4+ plants spaced or thinned 8‐12”apart. You can also try the hilling method in a 3’x3’ area by creating a mound at each corner and plant 3‐4 stalks or seeds per mound. You can cover new plantings until seedlings are a few inches tall to deter birds from uprooting seedlings. Keep new beds well weeded.

Most varieties will produce two ears per stalk. You can extend your corn season by doing successive plantings through early summer or plant a selection of varieties that mature at different times.

Water Requirements

How much water your plants will require depends on the soil and weather. Corn is somewhat drought tolerant, but it yields best with a steady supply of moisture, especially during tasseling. Corn prefers drip or flood irrigation, or deep hand watering. A 1” layer of compost over planting area helps maintain soil moisture.

Fertilizing

Corn is a very heavy feeder. Use a high nitrogen foliar spray such as fish and kelp every 7‐14 days until the plants begin to tassel at the top of the plants. Then stop fertilizing.

Harvesting and Storage

Most varieties will be ready for harvest 3 weeks from when the first silks appear on baby ears. Ripe ears have dry, brown silks and ears that feel full to the tip. A further test is to peel back the husk a little (do not pull the silks down) and pierce a kernel with your fingernail. If it has a white milky juice it is ready to eat. If the juice is clear, wait a few days.

Sweet corn is best eaten immediately after harvest. It can hold its flavor for 2‐4 days in the refrigerator. Older sweet corn is great for chowders and canning. Sweet corn can also be dried or frozen when removed form the cob.

Popcorn, flour corn, and ornamental corn are all picked when husks are brown and partially dried. Ears are hung and dried in a warm, well‐ventilated area or solar drier. Kernels are ready for storage when they fall off the cob or are easily rubbed off.

Pests and Diseases

• Damping‐off occurs in cool, wet weather and prevents seedlings from emerging or causes seedlings to die off. Replant new seeds in an area with better drainage, or add more compost and wait for warmer weather.
• Aphid damage often appears as a sooty coating on the plants. You may find large colonies of green or grey bugs or see the white aphid skeletons. The many remedies for aphids include insecticidal soap or horticultural oil sprayed every 7‐10 days.
• Snails and slugs will chew the leaves or eat new transplants when they feed at night. They often leave iridescent trails on leaves and the ground. Slug baits and beer traps are just two ways to control them.
• Rust appears as rusty brown spots or blisters on leaves and stems. Pick off infect parts and spray with a fungicide such as Serenade to prevent the spread of the fungus.
• Leaf spots and blights appear as long circular or elliptical, grey spots on leaves. They are fungus that overwinters on corn debris left in the garden. Serenade and copper can prevent the spread of them.
• Corn borers will eat holes in whorls of emerging leaves and developing ears. Borers can also eat inside the stalks and cause them to fall over. Fallen stalks should be removed. Otherwise, you can spray Bt or Spinosad to control populations.
• Corn smut is a fungus that overwinters in the soil where corn previously grew. It causes infected ears to develop white galls which turn grey. It can also infect at the base of plants and cause plants to die. Corn smut is actually a delicacy in some cultures. Remove and destroy infected plants. There is no control for corn smut.
• Rots can affect all parts of the plant. The various corn rots are Fusarium fungal disease and are best prevented with good soil drainage and air circulation. Be sure to rotate your crops and plant resistant varieties to further avoid problems.
• Mosaic Virus causes yellow spots and streaks in the whorls of new leaves and stunts plants. The virus is transmitted by aphids and avid aphid control can help prevent infection. There is no other control for mosaic virus.