Eggplants - SARE

Cichorium endivia (Asteraceae or Compositae family)

Production

Soil Preparation

If either phytophthora blight or verticillium wilt is an issue, biofumigation has shown some effectiveness to reduce the incidence.
Apply compost and other amendments based on the results of a soil test.
Spread lime as needed to increase both the pH and Ca levels. Dolomite lime will also increase Mg levels. Spread gypsum when calcium levels are low but pH is correct.
A fertilizer company can add OMRI-listed potassium sulfate to compost if it doesn’t have enough K to meet the crop’s needs. If this isn’t possible, spread the correct amount of fertilizer and incorporate it before planting. Alternatively, you can side-dress it during cultivation. Divide the recommended rate of the soil test in half if side-dressing.
Most vegetable crops remove little P, but at times your soil test result will call for additional P. Unfortunately, there aren’t short-term options for an organic grower to increase the available P levels in the soil. Through the use of animal-based fertilizers, P will build up to a level in the soil that is sufficient for all vegetable crops.
Incorporate compost and amendments as needed. Plant eggplants in high raised beds covered with plastic mulch. Infrared transmitting (IRT) mulch will help warm up cold soil for the earliest plantings.

Common recommended fertilizer rates¹

Nitrogen	Phosphorus	Potassium	pH
130	0-200	0-200	6.0-6.4
¹Rates are for New York and are from Cornell University’s Nutrient Guidelines for Commercial Vegetable Production (2019). Check the Cornell website for updated guidelines, or consult with local experts for recommended rates outside New York.

Varieties

Colorado variety trial
Irene has some verticillium wilt tolerance

Greenhouse and seeding guidelines

EZ Seeder seeding plate #16
Start seeds in the germination chamber or when you can keep your greenhouse warm both day and night. Germination is poor at lower temperatures.

Cell pack tray	Germination temp	Growth temp	Hardening off	Notes
288	80°–90°	70°–80° daytime 65°–70° nighttime	Pot up into 38-cell trays or 3- to 4-inch pots after the first true leaves fully develop.	Notes

Number of successions

Some growers like to spread their risk by planting eggplant twice. In seasons when you transplant eggplant into the field under relatively cold conditions, the second crop produces much better.

Greenhouse guidelines

When true leaves have developed, repot into 38-cell trays or 3- to 4-inch pots. Choose the size that allows you to hold the plant until the transplanting date. Bigger pots means bigger plants with more time in the greenhouse but also more work to transplant in the field.
Keep the temperature around 70°–80° during the day and 65° at night for the best-quality plants. If you notice yellowing, make sure the temperatures are high enough during the day. When temperatures drop too low, premature flowers form that you will need to pick off.
If necessary, feed plants with an OMRI-listed fertilizer to keep them healthy.

Transplant readiness indicators

Harden plants off outside; plants that are lush don’t perform well in the field.
Transplant in the field when plants have enough of a root ball to hold the pot together.

Transplant tips

The following tip is useful when you have harvest lanes, where every 8 or 10 beds are separated by a grass strip: Mark a 4-foot “walking break” on the plastic mulch every hundred feet and don’t plant anything in that 4-foot strip. This will make harvesting easier by allowing you to easily pass through the crop when removing buckets. Instead of carrying the buckets of eggplants to the headland, one can walk through the crop (instead of over) to the left or right and place the buckets in the harvest lane to be collected by truck or other vehicle.
Transplant in the field when the soil temperature is above 65° and before plants get too big.
Planting eggplants early—before the soil is above 65° and when they can be exposed to cold nights—can set the plants back. Plant when they can get off to a successful start.

Since eggplant is a tropical fruit, IRT plastic mulch is the preferred material to help warm the soil for early-planted crops.

Water wheel transplanter

Rows	In-row spacing	Planting depth (inches)	Notes
2	18 inches	As deep as possible through plastic

Cultivation procedures (with plasticulture)

After transplanting, cultivate once or twice between plastic with a rolling cultivator or Spyder to control weeds. Cover the wheel tracks with rye straw at a rate of 3 lbs. per foot. (One 600 lb. round bale covers 200 feet of wheel track.) Increase this amount when using an early cutting of orchard grass because hay breaks down much faster than straw. Over time, hay and straw mulch will release a significant amount of K and other beneficial properties like silicon, contributing to long-term soil health. Mulching also protects crops from soil splashing. This reduces soilborne diseases and time spent cleaning produce after harvest.

Cultivation procedures (without plasticulture)

Ideally, control weeds when they’re in the white thread stage. When using precision cultivation tools, make sure plants are established and won’t be uprooted by implements operating close to the crop.
When plants aren’t established, only use side knives or sweeps.
When plants are established, use a finger weeder in combination with side knives for best weed control. Alternatively, if you want very slight hilling, use spring hoes in combination with side knives.
Hand hoe or hand weed between plants.

Frost, disease and insect protection

For the early plantings, use floating row covers to protect against frost, and consider keeping these covers on to protect against potato flea beetles as well. Use 10-gauge wire to support the row cover, since abrasion against the cover will damage the plants. Remove covers at flowering for pollination.
For control of Colorado potato beetles, move eggplants far away from last year’s potatoes and eggplants. Use a Bacillus thuringiensis subsp. tenebrionis strain (as in the product Novodor™) to kill potato beetles in the larvae stage, with the rate depending on larvae size. You can use a spinosyn-based product like Entrust to kill adults, but only spot spray where there is a presence. To prevent killing beneficial insects and pollinators, avoid spraying during the day.
To prevent anthracnose, use hot-water treatment of seeds, crop rotation and plastic mulch in combination with straw or a weed barrier.

Verticillium wilt has many hosts in the field and it’s very difficult to rely entirely on rotation to eliminate this disease. Using somewhat-resistant varieties like Irene is a good solution. To help reduce disease pressure, mix Streptomyces iydicus (as in the product Actinovate SP) and/or an extract of giant knotweed (as in the product Regalia) in a water solution and drench the complete tray before transplanting to prevent many soil- and foliar-borne pathogens, and to build immunity against them. Wear protective clothing and gloves when handling these products.
Similarly, Phytophthora blight remains in the soil for a long time, and biofumigation has shown some effectiveness. (Additional information on phytophthora capsici.)

Other cultural practices

Irrigate frequently for optimum yield and plant health. Frequency depends on soil type, evaporation, precipitation and the particular needs of the crop.

Double cropping and/or cover cropping

Remove plastic and drip tape soon after the last harvest.
Work under any mulch and crop residue to avoid insect or pathogen buildup, and plant a cover crop. In the northern United States and Canada, you can follow eggplants with rye and vetch. Adjust accordingly in other regions.

Harvest

Yield	An average of 1.75 lbs. per row foot is common, but growers using protected tunnels report much higher yields.
Standards	Harvesting¹ 5–7 buckets (20 lbs. per bucket) per person, per hour
Standards	Washing Ideally, eggplant is not washed but is carefully sorted and counted.
Tools and supplies needed	Scissors or pruning shears and ⅝-bushel or ½-bushel buckets.
¹Harvest rates don't include the time required to transport crops from the field to a wash and pack shed or storage facility.

Ready-to-harvest and quality indicators

Fruits are 8–10 inches long and free of blemishes. Asian and Thai eggplant have similar requirements as the standard Italian type.
Eggplants must be firm, filled out and heavy in relation to their size.

Harvest procedures

Wash hands and sanitize pruning shears or scissors before harvesting.
Each person harvests 1 bed at a time (1 row per bed). Mark the spot where you stop harvesting with a bright flag so that you can begin there the next time you harvest, because it might not be obvious when you return.
Cut eggplants from the plant with scissors or pruning shears, leaving a small (¾ inch) stem on the fruit.
If you grew the eggplant on plastic mulch and wheel tracks are mulched with straw or covered with weed fabric, the fruit is usually clean, making washing unnecessary.

Washing and packing procedures

Eggplants are sensitive to sunburn. Don’t leave them in the field in uncovered harvest boxes or buckets where they can be exposed to the sun on hot days.
Wash hands and rinse boots before entering the wash-and-pack shed, and cover up field clothes with a bib. If a long-sleeve shirt contains soil, remove this as well.
If washing is necessary, use a rinse conveyor washer or a brusher washer, or rinse off by hand when dealing with smaller quantities. Add a sanitizer like hydrogen peroxide and peracetic acid to the water in the circulation tank of the rinse conveyor vegetable washer. Use the guide How to Wash Produce Using a Peracetic Acid Solution to establish how much sanitizer solution to add to water. Make sure you use the appropriate pressure to avoid fruit damage.
Avoid dunking eggplants in cold water, as this can create cross-contamination of foodborne pathogens that can be absorbed through the skin of the fruit.
Make sure the eggplants have a chance to dry off before packing them into boxes.
Sort fruit by size in a well-lit location whereby each box contains approximately 16–18 Italian eggplants, or 30–35 Asian eggplants, in waxed 1¹⁄9-bushel boxes. Pack small Thai eggplants in ½-bushel boxes.

Additional resources

Packing and storage summary for eggplants

Packing in the field	½-bushel or ⅝-bushel buckets
Packing for delivery	Traditionally, a count of 16–18 Italian eggplants goes into regular 1⅑-bushel boxes (with different counts for other types), but in the end each box should contain 33 lbs. of eggplants. If you aren’t able to fit 16 eggplants in a 1⅑-bushel box, you have allowed them to grow too large for customers’ preference. Pack Thai and Asian eggplants in ½-bushel boxes that weigh 15–16 lbs. each. As these types are much more variable in size, they are usually sold by weight. See the International Federation for Produce Standards for the correct PLU code. Add the prefix 9 for organic crops.
Storage	At 50°–54° and 90–95% humidity. Don’t store below 50°. Eggplants are sensitive to ethylene exposure. Allow for good air exchange and don’t store with crops that release ethylene.

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the Sustainable Agriculture Research and Education (SARE) program. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.