Heat-Tolerant Eggplant Trials

Summers are hot in central Virginia, where I garden at Twin Oaks Community. Because we feed as many as 100 people from our gardens, it’s important that we grow reliable cultivars that’ll do well in our intense summers. Over the past few years, I’ve been trialing a number of eggplant cultivars to see which performed best in heat. I kept accurate, detailed records throughout the trials, and what follows are the results. You may find them useful when deciding what to grow in your own plot.

Origins of the Trials

Long ago, the gardeners at Twin Oaks grew the hybrid ‘Dusky’ eggplant, which bears a classic oval, dark-purple, 6- to 7-inch fruit. The 24-inch-high plants are fairly short and are lower-yielding than some bigger types. We grew 270 to 325 row feet of ‘Dusky’ to provide food for 100 people, and later on, we decided to try growing other cultivars.

In 2006, we planted lots of different eggplants: ‘Swallow,’ a long, thin purple-black hybrid; ‘Violetta Lunga,’ an open-pollinated (OP) long purple eggplant; ‘Listada de Gandia,’ a purple- and-white-striped, egg-shaped fruit; the black, egg-shaped ‘Early Black Egg’; ‘Black Beauty,’ with its dark-purple egg shape; and, for the first time, ‘Nadia,’ a large, purple-black, teardrop-shaped fruit.

We grew 10 to 30 row feet of each, for a total of 120 feet, along with 210 feet of ‘Dusky,’ the cultivar we were familiar with. Interestingly, ‘Dusky’ wasn’t as productive as some of the new cultivars. So, in 2007, we planted 90 feet of ‘Black Beauty,’ 90 feet of ‘Nadia,’ and 45 feet of ‘Early Black Egg,’ along with 45 feet of ‘Dusky.’ (Don’t ditch a cultivar based on one year’s experience!) We reduced the planting to 270 feet, confident that this amount would feed us.

Explorations in Heat Tolerance

By the end of 2007, we were convinced that ‘Nadia’ was the way to go! With positive results behind us, we focused on ‘Nadia’ from 2008 to 2011, and we were able to reduce our row feet because the yield was so high and reliable. We were happy farmers, with plenty of good eggplants and space saved for other crops. We didn’t know the next year would be so different.

Although we loved ‘Nadia,’ we discovered its Achilles’ heel. The summer of 2012 was hot, and ‘Nadia’ couldn’t cope. For a while in early summer, it didn’t grow at all — no new flowers, no new fruit. How hot are we talking about? We’re in central Virginia, in American Horticultural Society (AHS) Heat Zone 7. (Heat zones indicate the average number of days each year that a region experiences temperatures above 86 degrees Fahrenheit — the temperature at which many plants suffer physiological damage. Heat Zone 1 has only one day above 86 degrees each year; our Zone 7 has 60 to 90 days above 86 degrees.)

Because of the heat-related problems with ‘Nadia,’ we decided it would be wise to prepare for more hot summers and trial some heat-tolerant eggplant cultivars. We settled on a combination of ‘Nadia’ and some other catalog offerings, seeing sense in planting a mix of fast-maturing and heat-tolerant (but slower) cultivars. In addition to hybrids, we chose a couple of promising OP cultivars recommended for Florida and Texas (see “Eggplant Profiles”).

Yields Compared

Beginning with the 2013 growing season, we compared 60 row feet of ‘Nadia’ with 22 feet each of ‘Epic,’ ‘Traviata,’ and ‘Florida High Bush.’ All have tall, upright plants; large, purple-black, teardrop- or pear-shaped fruit; and claimed to be heat-tolerant.

Harvests started on July 25 — later than usual because of cool weather. We harvested three times a week until Oct. 17, and counted fruit harvested per plant from each cultivar, but didn’t weigh them. I was surprised how few fruits each plant provided — about six. In the first weeks of harvest, ‘Nadia’ produced the largest fruits and the most fruit per plant, but this soon leveled off.

Final results showed that ‘Traviata’ yielded well, with an average of 7.3 fruits per plant. ‘Florida High Bush’ followed with 6.3 fruits per plant, ‘Nadia’ with 6.1, and ‘Epic’ with only 4.4. But we later found out that the planting location for ‘Epic’ had affected yields. We believed ‘Florida High Bush’ had the smallest fruit, but we hadn’t weighed them, so we decided to do that the following year.

Ironically, 2013 was one of the coolest summers we’d had in a long time. At the time, we joked that we could keep hot summers at bay by conducting heat-tolerant eggplant trials!

The following summer wasn’t hot either. We grew the same four cultivars and recorded the weight of each harvest, as well as the number of fruits produced. We got better results all around. ‘Nadia’ gave the best yield per plant at 13.4 fruits. ‘Epic’ was second with 12.5, ‘Traviata’ followed with 11.7, and ‘Florida High Bush’ lagged behind with 6.8 fruits per plant. These numbers all compared well against the 2013 range of 4.4 to 7.3 fruits per plant.

Our record-keeping was helpful in seeing the flow of the harvest. All cultivars peaked on Aug. 6. Additionally, we discovered that the size and weight of each fruit was very similar for all four cultivars in 2014’s mild summer.

‘Florida Market’ Doesn’t Cut It

2015 didn’t have a hot summer either! We tested the same four cultivars again, along with another reputedly heat-tolerant OP, ‘Florida Market.’ During the warmest months, ‘Epic’ won at 4.1 fruits and 3.4 pounds per plant, with an average of 0.84 pounds per fruit. ‘Traviata’ came in second at 3.1 fruits and 2.4 pounds per plant, with an average of 0.79 pounds per fruit. ‘Nadia’ was third at 2.3 fruits and 1.8 pounds per plant, with an average of 0.75 pounds per fruit. ‘Florida High Bush’ beat ‘Nadia’ on tonnage at 2.1 pounds per plant, but bore smaller individual fruits.

For the whole 2015 season, ‘Epic’ also did best, both in number of fruits per plant (10.7) and weight per fruit. ‘Traviata’ produced 8.9 fruits per plant, ‘Florida High Bush’ produced 8.2, ‘Nadia’ produced only 8.0, and ‘Florida Market’ produced only 7.5. Because the latter cultivar had smaller fruits and a much lower yield, we scratched it from future trials.

Finding the Right Balance

For 2016 and 2017, we planted the same number each of ‘Nadia,’ ‘Traviata,’ and ‘Epic,’ to benefit from the strong points of each, make comparisons simpler, and be resilient in the face of erratic weather. Unlike previous years, we counted some very hot days: 63 days above 90 degrees in 2016, and 52 days in 2017.

In 2016, by the end of July, the 26 ‘Nadia’ plants produced 31 eggplants, the 26 ‘Traviata’ plants produced 30, and the 26 ‘Epic’ plants yielded by far the most at 73! ‘Epic’ fruits were largest too, at 0.9 pounds per fruit, with ‘Nadia’ coming in second at 0.8 pounds and ‘Traviata’ third at 0.7 pounds.

By the end of August, ‘Epic’ was the victor, yielding a staggering cumulative 287 eggplants that averaged 0.8 pounds each. There was a large gap between the ‘Epic’ plant’s totals and the totals of the others, with the second-highest yield being ‘Nadia’ at 125 eggplants. After producing high cull levels in August, ‘Traviata’ rallied in September, and in that month, produced 160 eggplants with a total weight of 112.5 pounds.

‘Epic’ was our 2016 champion eggplant in terms of total yield and weight per fruit. The cultivar’s impressive leap off the starting blocks kept it ahead of the pack for the season, and it even rallied in late October after some hot weather.

My experience suggests that eggplants are one of those crops where hybrids win every time. The Florida OPs couldn’t compare with the hybrids we trialed. ‘Epic,’ ‘Traviata,’ and ‘Nadia’ are all good eggplant cultivars with sturdy upright plants and large uniform fruits. If you garden in a hot climate, I recommend that you grow all three, as we decided to do, because they did well in tandem.

In the face of hot summers, a changing climate, and the need for good food, conducting these eggplant trials gave us important information for our gardening future.

Eggplant Profiles

These are the cultivars we considered. You should explore which ones produce best in your environment. Don’t be afraid to experiment like we did!

Hybrid Cultivars

‘Traviata’: Harvest 60 days from transplanting; 6 to 8 inches by 3 to 4 inches, with good flavor. Recommended in Florida.

‘Epic’: 64 days; 8 inches by 4 inches. Recommended in Florida and Texas.

‘Night Shadow’: 68 days; perhaps smaller than ‘Epic.’

‘Irene’: 69 days; 6 to 7 inches by 5 inches. Great flavor; big plant; productive.

‘Classic’: 76 days; heavy yields; high quality, but doesn’t perform well in cool conditions. Recommended in Florida and Texas.

‘Santana’: 80 days; large, continuous setting. Recommended in Florida.

Open-Pollinated Cultivars, Recommended in Florida and Texas

‘Florida High Bush’: 80 days; reliable; large fruit; drought- and disease-resistant.

‘Florida Market’: 83 days; large; excellent for the South but not for the Northeast.

Eggplant Seed Sources

• Baker Creek Heirloom Seeds
• Harris Seeds
• High Mowing Organic Seeds
• Johnny’s Selected Seeds
• Osborne Quality Seeds
• Reimer Seeds
• Seed Savers Exchange
• Stoke Seeds
• Territorial Seed Company

Pam Dawling has grown vegetables at Twin Oaks Community in Virginia for over 25 years, and often presents at MOTHER EARTH NEWS FAIRS. Her latest book is The Year-Round Hoophouse.