How to grow eggplants in a greenhouse

How To Grow Eggplants In a Greenhouse | Ultimate Guide

Eggplants (or aubergines to our European cousins) are a very versatile vegetable to grow in your greenhouse.  They are fab in so many different recipes.  

There are also a wide range of varieties offering a range of different colors including, red, pink white, black and purple.

Eggplants can be tricky to grow but fear not, as we’ll step you through the entire process with our ultimate guide on how to grow eggplants in a greenhouse!

SowTransplantSpacePlant careHarvestSeason
MarSow in seed trays.

Transplant seedling to small pots.
50cmProvide support to fruits.After 20 weeks.Jul-Oct

Before we discuss how to sow eggplants, it’s best to start by discussing how many eggplants should be sowed.

A single eggplant should provide you with anywhere between 5 to 10 fruits in a growing season.

Use this as a way of gauging how many plants you might need to provide you and your family sufficient eggplants over the year.

It’s always worth sowing a couple extra just to make sure that you have sufficient plants should one of them run into a problem growing.

Eggplants should be sowed in March (early March ideally), to allow enough time for the plant and fruits to mature.

So how do you sow eggplants?  Follow these simple steps.

  1. Fill a seed tray with potting compost.
  2. Water the tray with a watering can with a fine rose. Watering at this stage will mean that you won’t run the risk of washing the seeds to the corners of the tray later.
  3. Make a series of holes in the compost, about an inch deep and 5cm apart.
  4. Pop one seed into the hole.  How many you sow is up to you however sow a few more than what you need just in case some seeds don’t germinate into seedlings.
  5. Lightly sprinkle a thin layer of potting compost over the seed tray (a few millimetres is fine). This task will be easier if you use a garden sieve.
  6. Gently press down the top of the compost to ensure that the seeds are making good contact with the soil.
  7. Lightly water the tray once again.
  8. Place the tray in a warm, sunny spot and try to maintain a temperature of 65F to 70F (18C – 21C).  A heated propagator or mat might make this easier.

Keep the compost moist while the seeds germinate. Your seedlings will germinate within 7 days.

Eggplants can be a tricky plant to grow so it’s best to choose a reliable variety (see Best Varieties of Eggplant section of this guide).

Transplanting eggplants

Once the “true leaves” have appeared on the plant, transplant the eggplants to individual 7cm pots.

True leaves are the leaves that look more like the actual plant leaves rather than the seedling leaves.  They are usually the second or third set of leaves to start growing on a seedling.

To transplant the seedling to a 7cm pot, follow the steps below:

  1. Fill some pots with a general purpose compost.
  2. Use a pen or pencil to create a small hole in compost ready for the new seedling.
  3. Gently remove a seedling from the seed tray taking care not to damage the root of the eggplant.
  4. Use the pen or pencil to tease out the seedling.
  5. Place the seedling into the hole of the pot so that the seedling leaf is just above the soil surface.
  6. Water the pot thoroughly.

Soil & Location in a Greenhouse

As eggplants are hungry plants, they love a nutrient rich, loamy soil to grow in.  The loamy soil will help keep their roots moist during hotter periods of the growing season.

In terms of where to locate your eggplants, choose a spot that is in full sun that gets at least 5 hours of sun a day.  Therefore, eggplants might not thrive in a greenhouse positioned in shadier spots.

Eggplants also require good ventilation, so perhaps plant it near the greenhouse door or vent.  The ventilation will ensure that the plant stays sufficiently cool which will lead to a healthy, stress free eggplant!

Planting eggplants in a Greenhouse

Eggplants should be planted up into a greenhouse bed or container approximately 1 month after they were transplanted into their 7cm pots.

Greenhouse containers should be approximately 3-5 gallons (10-20 liters) in size.

Eggplants are sensitive to the cold.  Therefore, if you are planting your eggplants outside of the greenhouse you should do this no earlier than early May for warmer climates or wait until the end of May in colder climates.

Spacing eggplants

You should space your eggplants out by 50cm to allow the plant to grow properly.

Eggplants can grow 3ft tall so position the plant somewhere in the greenhouse that provide enough space for it to grow up into.

How To Care For Your eggplants in a Greenhouse

Eggplants don’t require too much aftercare, however you will need to consider the following points:

  1. Staking.
  2. Pinch out.
  3. Watering.
  4. Feeding.

Staking

The main stem of the eggplant will require staking to prevent it from flopping over.  A 1 meter bamboo cane would be sufficient for this task.

Some of the larger side shoots will require their own support stakes once the fruit begin to develop.

Pinch out

If the main stem of the eggplant is beginning to grow long in comparison to the rest of the plant, it might benefit from pinching out (removing) anything above the first 50cm of the stem.

This will encourage the plant to develop more side shoots and begin to bush out more.

Watering

Keep your eggplant well watered. How much water you give it will always depend on your particular greenhouse environment however, just remember to keep the soil moist but don’t constantly saturate the soil.

Don’t let the eggplant roots dry out as this will also cause the plant to bolt.

Feeding

Feeding should begin 1 month after the eggplant was planted into it’s bed or container.  At first, use a general fertilizer such as a 10-10-10 NPK.

Once the fruits have developed, you should swap to a fertilizer higher in potassium such as a 5-10-10.  The higher lievels of potassium will aid in the development of the eggplant fruits.

Apply this feed once a month until you have harvested all of the fruits from the plant.

When to harvest eggplants

Harvesting eggplantsDon’t allow the eggplants to become overly large.  Size doesn’t matter when it comes to these fruits.

It is far better to harvest eggplants when they are smaller.  The trick is to look at their skin.  If the skin is shiny, this is when they are at their tastiest.

If the skins turn a duller color, this likely means that they have turned a little more bitter.  They will also have become more pithy and spongy.  Not nice.

Common eggplant problems in a Greenhouse

Blossom end rot

Blossom end rot is a condition that causes the base of the eggplant fruit to turn black.  This is caused by a calcium deficiency.

Ensuring that the eggplants are regularly watered will prevent blossom end rot from occurring.

Greenhouse whitefly

Greenhouse whitefly is an aphid that feeds of the sap of some indoor plants such as eggplants.  You will know if your eggplants are suffering from a whitefly infestation as you will notice a sticky substance known as honeydew forming on the lower leaves of the plant.  Some leaves will begin to turn mouldy.  You might also notice small white flies when you disturb the leaves.

The best method of controlling whitefly is to introduce a biological control called Encarsia formosa.  These are a tiny parasitic wasp that kills the whitefly.  The eggs of these wasps can be purchased online.  The timing of deploying this control is critical.  The most effective time of introducing encarsia formosa is just as the first whiteflies are appearing.

Whiteflies are spread on the surface of other plants.  Therefore a greenhouse full of plants that have been grown from seed are less likely to be affected by greenhouse whitefly.

Greenhouse red spider mite

Greenhouse red spider mite are tiny mites that suck the sap from leaves of plants.  In severe infestations, these can kill the plant.

Red spider mites thrive in very hot, dry greenhouses.

One of the best ways of ensuring that your greenhouse and therefore eggplants, aren’t affected by this mite is to clean your greenhouse thoroughly at the end of the previous growing season.  We have developed a fantastic guide detailing how to clean your greenhouse.

If your greenhouse is experiencing an infestation, there are some extremely effective biological controls available.  For example, you could introduce a predator called Phytoseiulus persimilis that will hunt and kill the red spider mite without any harmful effects to your plants.

If any plants are heavily infested, remove them immediately from your greenhouse.  Ideally, these plants should be burned.  Definitely don’t add them to your compost heap as you may reintroduce the problem next year.

Best varieties of eggplant

Diamond – long fruits with a beautiful non-bitter taste.

Black beauty –  an older variety that is a early cropper.

Rosa Bianca – a pinkish white eggplant with a soft taste and no bitterness.

How Many eggplants Should I Grow in a Greenhouse?

As most eggplants will grow anywhere between 5 and 10 fruits, 3 – 4 plants should be sufficient to feed a family throughout the year,

Eggplant Greenhouse Growers Kit List

We have selected a kit list of key equipment and tools to get you growing tasty eggplants in your greenhouse in no time.  The eggplant varieties listed are the ones selected in our Best Varieties section above.  All of the items below are links to products available on Amazon giving you the added convenience of home delivery.

Tools

Seed propagation tray

Garden sieve

Seedling sower dibber

Greenhouse grow bags

Eggplant Seeds

Diamond

Black Beauty

Rosa Bianca

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