Eggplants in the Greenhouse

A greenhouse eggplant crop is relatively easy to grow as a commercial or hobby crop.

Although eggplant is not a regular food item for many people, it does have a place in the greenhouse production plan for those who like it and value its contribution to their cuisine.

The crop is about a six months long. It could be reduced to a shorter time but less fruit would be produced. Leaving the crop in the greenhouse more than six months would create a problem with plant height. Plants of most cultivars grow to six to seven feet tall in the six month time frame when trained in the way suggested below.

Any attempt to produce eggplant fruit through the lowest light time of the year, in all but high light levels, should be avoided. Good light levels are needed for good fruit production. With enough artificial light, fruit can be produced through otherwise low light periods.

Eggplant is usually served in a cooked state rather than fresh. Eggplant Parmesan is what many people think of when they consider eating eggplant at a meal. The eggplant fruit is sliced crosswise and the circular pieces are dipped in a batterand rolled in a crumb preparation before being fried or grilled. Eggplants can also be prepared in a casserole or as young stuffed fruit for individual sized servings.

Young Eggplants in Dutch buckets filled with perlite.

Plant Production System

Plants are started from seeds that can be placed in plant starter media such as rockwool, Sure to Grow or a soilless seedling mix. They can be transplanted into their final location in the production system in the greenhouse when they are three to four weeks old. The plants will have three to four true leaves by the time they are ready to be transplanted.

About four square feet per plant is the required greenhouse spacing. That is the same production space that is used for tomato plants. In the Dutch Bucket production system, two plants would be placed in a bucket. They are usually placed in opposite corners of the bucket. The perlite bag system has also been used for eggplant production. Three plants would be placed on a 42 inch long perlite filled bag. Space is left between the bags so that the plants are an average of 16 inches apart within the row. By the time the plants are a foot tall, they should be supported in their vertical position with vine twine. Although there is little danger of the plants falling over at this stage of growth, it is much easier to get the vine twine installed before the plants require it.

The vine twine is hung down from the support wire overhead or from the greenhouse structure if you only have a few plants. Because the plants will not be leaned and lowered like tomato plants are, there is no need to provide for the lengthening of the support twine once it has been installed. It can just be tied to the support wire or the part of the greenhouse support structure used to support the plant. The bottom end of the twine is fastened to the stem of the plant under a leaf. If a vine clip is used, the vine twine is pinched in the hinge of the clip and the clip is fastened around the stem under a leaf. Twist ties can be used if you have only a few plants. They are readily available but take a little longer to install. As the vine twine hangs down beside the stem of the plant, place the twist tie between the plant and the vine twine, wrap both ends around the vine twine and then bring the ends together on the opposite side of the stem just under a leaf. Twist the ends of the twist tie together. Clips or twist ties should be installed every eight to ten inches up the stem as the plant grows.

Some growers twist the vine twine around the plant stems instead of using clips or twist ties. Twisting is a time saving procedure used by some big commercial growers. This is a good way to break many of the plant stems unless you have developed your skill in performing this operation,

Double Top The Plant

Once the plants are twelve to fourteen inches tall, small suckers or branches will start to grow between the leaves and the main stem of almost every leaf. Those are all broken out to keep the plant growing with only one stem until a major branch develops at a height of 8 or ten inches up the stem from the bottom of the plant. This will be a much more vigorous and larger branch than has appeared on the plant to this point in its growth. It will be allowed to grow and will be clipped up to its own vine twine to support its vertical growth. The rest of the suckers or branches will be removed from the main stem and from the branch that is retained so that the plant will have two stems and growing points.

Flowers and Fruit

The first flower or cluster of flowers will develop just above the same node as the first major plant branch develops. If there is more than one flower, most growers will remove all but the largest flower. If, however, you have two flowers that are about equal in size, you can leave them both on the plant to produce fruit. This is because you will be picking the fruit when they are two thirds to three quarters their mature size. When you pick an eggplant fruit before it is fully grown, it is very tender and tasty. The skin is also very tender. This is a real advantage to the consumer of the eggplant no matter in what way it is prepared. The skin on a mature eggplant can be tough and resistant to the bite of those who use synthetic teeth.

Eggplant flowers like tomato flowers are self pollinating flowers by their design. They are, however, even easier to get pollinated and have fruit set in the greenhouse than are tomato flowers. To make sure the flowers get pollinated, you can tap the flower stalk with a pencil when the flower petals are fully open. It is not necessary to have bumblebees or use a more sophisticated pollinating devise with eggplant flowers. If you have bumblebees in the greenhouse to carry out pollination with other plants, they will visit the eggplant flowers also. If bumblebees are present, you will not need to do any hand pollinating. The bumblebees will do an adequate job.

Harvest the fruit by cutting it off the plant with pruning cutters. The stem of the fruit is very thick and does not separate from the plant easily nor without damage to the plant unless it is cut. As mentioned above, the fruit is harvested before it reaches its full size so that you can enjoy a better tasting, more tender fruit no matter how you prepare it in the kitchen. The tougher skin that develops when the fruit is mature is helpful in the shipping and marketing of the fruit on a commercial basis. By growing your own, you can choose the quality and not be concerned about the way other people would handle the fruit.

Harvesting the fruit before it is fully grown and mature cuts the time from seeding until first harvest. You get to enjoy tastier fruit sooner. You will also be able to get a few more fruits per plant. Keeping the fruit picked before they mature keeps the plant growing and setting fruit better and longer.

Leaf Pruning

When the eggplants in the greenhouse are about 4 feet (1.25 m) tall, you should start removing a few of the older leaves at the bottom of the plant. Remove four or five leaves per week per plant once you start leaf removal. New leaves are being produced at the top of the plant as the main stem and the branch each continue to grow.

The absence of leaves at the bottom of the plant allows for better air movement around the base of the plants. This reduces the risk of fungus disease development.

The leaves are broken off the stem at the natural breaking point where the leaf attaches to the stem. Press down on the leaf petiole near the stem of the plant. If the leaf petiole does not break all the way off, lift up on it to finish the break without tearing a strip of tissue from the stem of the plant.


Eggplant fruit produced by different cultivars have a range of colors and shapes. Before growing a given cultivar, you will need to decide whether you want a traditional size and shaped fruit or whether you want to grow one of the variations. You may want to grow two or more cultivars having different fruit types if you really like eggplant and may want to check out the results of growing your own. Most of the pictures are of plants that produced a typical one pound (450 g), dark purple fruit at maturity. Cultivars like this include Orion, the one in most of the accompanying pictures. The white fruited cultivar in the picture is Tango. We have also grown Zebra. The Zebra fruit color is a light purple with white strips.

Small packs of seeds of several different cultivars including Tango and Zebra are available from Johnny.

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