When I first tried growing eggplants (or aubergines) in my area under the mountains (zone 6B), they didn’t do so well. They were growing outdoors, and during the heat of summer, they kept dropping their flowers. I thought they’d never set fruit. But come autumn, they started producing tender and tasty fruits that soon fueled my eggplant obsession. I was now on a mission to troubleshoot my eggplant growing process.
Eggplants become stressed and stop producing fruit for several reasons, mainly insufficient water and temperatures above 90°F (32°C). Aside from dry conditions, flowers could be dropping because of cold weather, pollination issues, soil deficiencies, or pest damage.
When the eggplants’ flowers drop or don’t turn into fruit, it’s rarely just one thing, so let’s explore all the possible causes together:
1. Lack of water
Eggplants are a particularly thirsty plant, and they don’t do well in dry spells. Lack of water leads to a stressed-out plant, which in turn can drop flowers and not produce any fruit.
Even if they seem otherwise healthy, when eggplants drop their flowers in the heat of summer, the main culprit is usually water. To stay on top of your plants’ needs, use a rain gauge to check the humidity levels in your soil.
Eggplants require at least one inch of water per week during normal conditions, and two inches of water per week during hot, dry weather. It’s best that you provide most of this water in one session in normal weather, and twice a week in hot weather.
Long sessions of deep watering are better than daily superficial ones because we want that water to reach the soil at deeper levels – ideally 12 inches into the ground. The heat of summer can easily evaporate water from the soil’s first couple of inches, leaving the roots thirsty and dry.
2. Lack of pollination
Eggplants are self-pollinating plants, meaning they have a “perfect”, or “complete” flower that has both male and female components. They still require pollination, but this easily occurs through light gusts of wind or by means of insects such as bees, butterflies, or moths.
During hot weather, or high humidity levels the pollen may become sticky, making it hard for it to fall from the pistil and pollinate the flower. In some cases, the pollen may become inactive entirely, which leads to eggplants dropping flowers.
If you’re growing your eggplants in a greenhouse or a polytunnel, where airflow is not optimum and pollinators don’t have that much access, hand-pollinating would be the next best thing you could do. Gently place the brush inside the flower, pick up the pollen and move it around.
If the conditions allow for it and the pollen is still active and not too sticky, a gentle weekly tap on the plant may be enough to assure pollination, but encouraging natural pollinators is always the best option. Try growing flowers and companion plants that attract bees, such as borage, marigolds, daisies, lavender, sunflowers, and many others.
3. Exposure to harsh temperatures
Eggplants aren’t meant to thrive in temperate climate conditions, so it should come as no surprise that they hate weather that’s out of their comfort zone.
If the temperatures drop below 60°F (16°C), it may be a cause for the eggplants dropping their flowers and not setting any fruit. Lower temperatures inhibit various vital functions, and the plant will go into survival mode, shedding its flowers in the process. There’s not much you can do about this, other than growing your tender plants undercover if you know your climate to be harsh.
When the weather is particularly hot, exceeding 90°F (32°C), it may also result in the eggplant’s pollen becoming inactive or sterile entirely. Drastic shifts in temperature also stress out the plant’s entire system, which makes it stop producing until the weather becomes more mellow.
Eggplants do best in full sun, so if you’re trying to avoid scorching weather by planting them in the shade, that’s not a solution either. The best thing you could do is make use of shade cloth during the hottest part of summer and protect your plants, especially in the afternoon.
4. Soil that is defficient in nutrients and minerals
Eggplants love well-drained, sandy soil that is rich in minerals, particularly nitrogen and phosphorous during the bearing fruit phase of the plant. Other important elements include potassium, phosphorous and magnesium. You can add all these elements into the soil by feeding it regularly with organic fertilizers.
Always choose a balanced fertilizer (10-10-10), and don’t feed the eggplants too often, they don’t need it – no more than every 4 weeks. Other organic options include fish fertilizer, compost tea, bat guano, or seaweed.
Avoid planting your eggplant seedlings into boggy, wet soil, which can lead to fungal disease and stunted growth. You can improve the structure of your soil by adding organic matter. Compost is always the answer to getting better crops, and a layer of 4 to 6 inches of compost will do wonders for the structure of your soil, as well as the nutrition levels.
5. Insect and pest invasions
If your eggplants aren’t producing fruit, check them for signs of disease or pests. Insects hide under the foliage, making them difficult to notice, and they can have a huge impact on your plant’s development.
Prevention is key, so inspect your plants weekly and don’t allow damage to get out of hand. The most harmful insects that like to prey on tender eggplants are:
- aphids – they cause the leaves to curl and stunt the plant’s growth;
- flea beetles – they generally attack seedlings, but once the plants grow, they can protect themselves;
- spider mites – they attack in hot weather, building a web across the foliage and sucking on the plant’s sap;
- Colorado potato beetles and hornworms – they both quickly chew on leaves and can devastate entire crops.
You can fight these pests using organic pest control methods, mechanical methods in particular. You can spray the aphids away with water and manually pick the larger insects. Protect the seedlings when they’re young with mesh or horticultural fleece. When all else fails, you can use insecticidal soap, neem oil, and many other available options.
6. Planting the wrong variety for your climate
Eggplants originate in Southeast Asia, and given their tropical heritage, they thrive in warm, rainy climates. Growing them in temperate climates, where we get long winters, and short growing seasons can be a challenge if we’re not strategic about it.
Plant out your eggplant seedlings too late in the season, and you may not get any fruit. Choose a variety with a long time to maturity, and you can only start picking fruit in late Autumn. It happened to me – my eggplants kept dropping their flowers in summertime, only to start producing some fruit in late September, early October.
Here are a couple of things you could do to ensure you can grow eggplants in your climate.
Firstly, look at the DTM (days to maturity) on the seed package before buying or ordering seeds. For short seasons, choose an early maturing variety (60-70 days) such as Aplegreen, Diamond, Orient Express, etc. Look for what the locals have been planting successfully for years in your area. You can try out mid-season eggplants (70-80 days) like Black Beauty and Violetta Lunga if your autumns are mild and long.
Secondly, either start your own seedlings early in a heated space – mid-February works best – or buy strong eggplant transplants if you’re not confident enough to start your own. Plant them out a couple of weeks after the danger of frost has passed. This will help you get a head start and enjoy eggplant fruits with perfect timing.
Thirdly, bypass your climate issues altogether and plant the eggplants inside a greenhouse or polytunnel, once the temperature allows for it. You’ll have other issues to watch out for, like pollination or high temperatures, but it’s your best bet when growing nightshades in a cool climate.
After reading this, you may decide that growing eggplants is too much of a hassle – they’re fickle about everything – soil, temperature, pollination, pests. But whenever plants are struggling, they have a way of showing it that points to the exact problem. So don’t give up on growing these great vegetables after one failed attempt, there are still many things you could try to grow eggplants successfully.