How to Manage Pests

Pests in Gardens and Landscapes

Cultural Tips for Growing Corn

In This Guide

Site selection

Plant your garden in a convenient location, where you can check it frequently. Choose an area near an abundant supply of water so you can water as needed easily. Vegetables do best if they receive full sunlight (at least 4 to 6 hours a day). Plant them in a well-exposed area in the garden, where they are not shaded by trees, fences, or walls. Try to plant away from areas that will be watered by lawn sprinklers.

Whenever possible, select a location that is not heavily infested with weeds, especially weeds such as field bindweed, nutsedge, and Bermuda grass that can be hard to control with hand weeding. Also avoid areas that have had previous disease problems.

Try to plant on level ground. Level ground is easier to work on than sloping ground. Vegetables will do well on a wide range of soils; they do best in well-drained soils. If your soil forms a clump when squeezed, then it is too wet; if the soil crumbles easily, it is a good soil to use. Damp soil surfaces encourage snails, slugs, sowbugs, and root diseases; fruit decay and leaf spot diseases may also increase. Soil amendments can make clay and sandy soils easier to work with, and correct soil preparation can improve poor soil.

Adding organic matter (compost, peat moss, manure, sawdust, ground bark) makes clay and sandy soils easier to work with. The soil should be kept at a pH level of 6.0 to 6.5. Lime or gypsum can be added to soils low in calcium.

Soil recommendation

Choose soils that can drain away and roots are able to penetrate the soil.

Soil improvement

Any type of soil can be improved with soil amendments. Heavy clay or sandy soils can be improved by adding organic material such as compost, manure, or leaf mold. Texture is an important consideration when choosing an amendment. An amendment that is granular and fine grained is important for container mixes. For gardens, a more coarse-grained amendment can improve drainage and aeration. Work amendments into soil by rototilling, raking, or double-digging.

Soil preparation

The preparation of your soil is just as important as adding fertilizer and soil amendments. Before working the soil, make sure it is moist but not thoroughly wet.

  1. Use a shovel, rototiller, metal bow rake, or all of them together to loosen the top 1 to 2 inches of soil. Rake the area to remove weeds and old crop debris. Be sure to dig out roots.
  2. Irrigate the plot deeply to encourage the germination of weed seeds.
  3. In a week or two, after a substantial number of weeds have germinated, work the area again to kill the weed seedlings. Be sure to break up the clods in the soil, as seeds planted in cloddy soil will germinate poorly and won't live long because the soil dries too quickly.
  4. Form soil into beds if desired, and plant while soil is still wet.

Time to plant

Warm days and nights provide the best climatic conditions for growing corn. Frost will injure the plants at any stage of growth. For germination, soil temperatures should be between 70° to 80° F and should not go below 55° F. Air temperatures above 95° F and drying winds may cause poor pollination. It usually takes between 70 and 120 days for corn to reach maturity depending upon the planting period. Corn planted earlier usually takes longer to develop than corn planted later on in the year. However, planting early may help reduce some incidence of disease, such as smut.

In a suitable climate, corn can be planted more than once a year for a continuous harvest.

Planting Dates for Corn in California*
North and North Coast
Monterey County north
South Coast
San Luis Obispo County south
March– July
Interior Valleys
Sacramento, San Joaquin valleys
Desert Valleys
Imperial and Coachella valleys
February – March
*Areas are large, so planting dates are only approximate, as the climate may vary even in small sections of the state. Contact your local UC Master Gardener program and experiment on your own to find more precise dates.

Planting Corn

Corn is generally direct seeded into the garden because it germinates so readily and is difficult to transplant. Corn should be planted on raised beds, made by adding large amounts of sifted compost or other soil amendments so that a bed is established above the previous level of soil. Beds should be about 36 inches wide with a row of corn on each side of the bed. Plants should be 8 to 12 inches apart in the row. Plant the seed 1 to 1.25 inches deep and firm the soil well over the seed. To insure pollination, plant corn in blocks instead of long rows. Make several successive plantings for a longer harvest period. Usually plant every 3 weeks in early spring to every week in the later spring period for successive harvests.


Most vegetables require fertilizer for growth. Organic materials, such as manures and compost, and inorganic materials, such as chemicals, can be used to fertilize plants. Using both types of materials usually provides the best growth. Manures and compost can be used to increase soil fertility. They are usually applied at 1 pound per 4 or 5 square feet. These materials should be worked into the soil several weeks before planting in order to allow it to decompose. Manure that contains straw, sawdust, or similar materials should be applied with a commercial nitrogen fertilizer. Generally, if the soil has been properly amended with compost or manures or other organic materials, the only nutrient needed is nitrogen, if anything. Some commercial nitrogen fertilizers available are urea, ammonium sulfate, calcium nitrate, and ammonium nitrate. Apply these fertilizers at rates of 0.5 to 1 pound of nitrogen per 100 feet of row.

If manure and other organic material has not been used, apply fertilizer that contains both nitrogen and phosphorus before planting. All commercial fertilizers are labeled by the percentages of N-P-K; nitrogen (N), phosphorus (P), and potassium (K). Some common mixed fertilizers are 5-10-5, 5-10-10, 8-16-16, and 12-12-12. Apply these fertilizers at rates of 1 - 2 pounds per 100 feet of row. After plants are 3 to 4 inches tall, sidedress nitrogen in narrow bands or furrows and water thoroughly after application, or apply through the drip system. Consider light but frequent applications of nitrogen fertilizer every 3 to 4 weeks. Avoid letting the fertilizer come into contact with the plant stems to avoid burning.

Application tips

Inorganic fertilizers can be sidedressed. Manures are more difficult to use as a side dressing and must be tilled into the soil.

Banding: Make a small groove an inch or two deep on both shoulders of the bed, 4 to 6 inches from the plant row and band in the fertilizer. Replace the soil and irrigate.

Broadcasting: Fertilizers can be scattered along the bed shoulders. Work into the soil soon after. This is less efficient than the banding method but will be more practical when the plants are so large that the bed shoulders are inaccessible for banding.

Where sprinklers are used, fertilizer may be scattered on the soil surface between rows before irrigating. Where drip or trickle tubes are used, apply fertilizer on the soil surface near the drip tube.

Watering Corn

Young corn plants have a rather coarse shallow root system, but as the plants mature the roots become more fibrous and can penetrate to a depth of 3 feet or more in the taller varieties. The soil should be well irrigated prior to planting. After germination, start regular irrigation using drip or furrow irrigation when the plants get 3 to 6 inches high. Weekly irrigation may be required depending upon the soil type and the temperature up until harvest. On hot days the corn leaves may roll up for an hour or so without harm. However, irrigation is needed if the leaves remain rolled up in the early morning.

Harvesting and Storing Corn

In the summer, corn reaches its prime eating condition about 3 weeks after tasseling; in spring or late fall the interval may be about 4 weeks. As the ears approach maturity, sugars change to starch, the hull becomes tougher, and the kernels pass through stages called pre-milk, milk, early dough, and dough. At temperatures around 60° F, the ear remains in good condition for about 5 days. At 85° F it passes through all these stages in 1 to 2 days. Ears are ready to harvest when the husk is tight, the silks are somewhat dried, and kernels are fully developed and, if punctured, show a milky liquid. Avoid disturbing the husks on ears that are not ready to harvest. If harvesting during dry and windy conditions or in temperatures above 95° F, harvest rapidly because corn will quickly lose quality. Pick the ears in the coolest part of the day and either refrigerate or use quickly.

Harvesting Dates for Corn in California*
North and North Coast
Monterey County north
July - October
South Coast
San Luis Obispo County south
Late June - early November
Interior Valleys
Sacramento, San Joaquin and similar valleys
June - early August
October - November
Desert Valleys
Imperial and Coachella valleys
May - early June
November – early December
*For other areas, contact your local UC Master Gardener program.
Ears of corn.

Ears of corn.

Seed bed preparation.

Seed bed preparation.

Amending soil to prepare for planting.

Amending soil to prepare for planting.

Bag of fertilizer.

Bag of fertilizer.

Irrigation shut off valve.

Irrigation shut off valve.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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