Eggplant in Zone 6A — Mountain West

Eggplant might seem like a stretch for high altitude gardening, but trust me, the taste of homegrown eggplant, grilled with a little olive oil and herbs, is worth the effort. Plus, in our intense sun, eggplant develops a rich, concentrated flavor you just can't find in store-bought. It's incredibly versatile in the kitchen, and there's a certain satisfaction in harvesting beautiful, glossy eggplants from your own garden.

Our short season and cool nights mean you have to be strategic, but with a little planning, you can absolutely grow eggplant in Zone 6A. Starting seeds indoors gives you a head start, and the Mountain West's low humidity helps minimize disease. With a 153-day growing season, you have time to get a harvest, even at altitude.

Starting eggplant indoors is essential for us Mountain gardeners to get a decent harvest. You'll want to sow your seeds indoors from mid-March through early April, about eight weeks before you plan to transplant them outside. This gives them a good head start before our unpredictable late springs hit.

Use seed trays with a good seed-starting mix, and make sure you provide plenty of warmth and light. Eggplant needs warm soil to germinate well, so a heat mat can be helpful. Bottom watering is a great trick to keep the soil consistently moist without damping off. Remember, our spring weather can be fickle, so starting early is key.

Transplant your eggplant seedlings outdoors from late May through mid-June, once the soil has warmed up. Before you plant them in the garden, you'll need to harden them off. This means gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade, gradually increasing the sun exposure each day.

Space your eggplant plants about 18-24 inches apart in a sunny spot with well-drained soil. Keep an eye on the weather forecast around transplant time. A late frost can be devastating, so be prepared to cover your plants if necessary. Our intense sun can also shock young transplants, so provide some temporary shade for the first few days if needed.

Eggplant needs consistent moisture to thrive, especially in our dry Mountain climate. We don't get much rain here, and the low humidity means the soil dries out quickly. Aim for about 1-2 inches of water per week, depending on the weather. You might need to water more frequently during hot spells.

The finger test is your best friend: stick your finger about 2 inches into the soil near the base of the plant. If it feels dry, it's time to water. Water deeply at the base of the plant, rather than overhead, to avoid wetting the foliage. Wet foliage in our cool nights can encourage fungal diseases.

Underwatering can lead to bitter fruit and blossom drop, while overwatering can cause root rot. Signs of underwatering include wilting leaves and dry soil. Overwatering symptoms include yellowing leaves and soggy soil. A good layer of mulch around your plants will help retain moisture and keep the soil cool.

Eggplant branches can get heavy with fruit, so providing support is crucial to prevent them from breaking or the fruit from touching the ground. Staking is the easiest and most effective method.

Install a sturdy stake next to each plant at planting time, driving it deep enough into the ground to provide good support. As the plant grows, gently tie the main stem to the stake with soft twine or plant ties. This will keep the plant upright and prevent the fruit from weighing down the branches.

Eggplant doesn't require a lot of pruning, but a little maintenance can help improve airflow and fruit production. Focus on removing suckers that grow below the first main fork of the plant. These suckers steal energy from the main branches.

Later in the season, you can limit the plant to 5-6 main branches to encourage larger fruit. Just pinch off any new growth that appears. As the first frost approaches in early October, you can remove any small, immature fruit to encourage the plant to put its energy into ripening the larger ones.

You can expect your first eggplant harvest from late July through mid-September, about 70 days after transplanting. The key is to harvest them when they're glossy and firm, but not too large.

A ripe eggplant will have a shiny, smooth skin and will feel slightly firm when you gently press it. If the skin is dull, it's likely overripe and may be seedy. Use a sharp knife or pruning shears to cut the eggplant from the plant, leaving a small stem attached. Avoid pulling the fruit, as this can damage the plant.

Eggplants will continue to produce throughout the season if you harvest them regularly. Keep an eye on the weather as the first frost approaches. You can harvest any remaining mature fruit, even if it's not fully ripe.

Here are some common problems you might encounter growing eggplant in the Mountain West:

Flea Beetles

• What it looks like: Tiny round holes in the leaves (shot-hole pattern). You'll see small, dark beetles jumping around when disturbed. The damage is usually worse on young seedlings.
• What causes it: These small jumping beetles feed on the leaves. They're most damaging to small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger. You can also try spraying with kaolin clay or neem oil. Interplanting with basil or catnip can help deter them. Healthy, vigorous plants tend to outgrow the damage.

Colorado Potato Beetle

• What it looks like: Yellow-and-black striped beetles and reddish-orange larvae feeding on leaves. They can quickly defoliate a plant.
• What causes it: These beetles are common pests of eggplant, potatoes, and tomatoes. They're attracted to the plants and can reproduce quickly.
• How to fix/prevent it: Hand-pick beetles and larvae off plants. Use row covers early in the season. Bacillus thuringiensis (Bt) is effective against young larvae. Pyrethrin sprays can also help.

Verticillium Wilt

• What it looks like: Lower leaves yellow, wilt, and die, progressing upward. One side of the plant may be affected first. You might see brown streaks in the stem if you cut it open.
• What causes it: This is a soil-borne fungus that can persist for years. Cooler soil temperatures favor it.
• How to fix/prevent it: There's no cure, so remove infected plants. Rotate crops with non-susceptible plants like corn or grains. Solarize the soil to kill the fungus. Plant resistant varieties (look for 'V' on labels).

Blossom Drop

• What it looks like: Flowers fall off without setting fruit. Small fruit yellows and drops. The plant looks healthy, but produces no fruit.
• What causes it: Temperature stress is the main culprit. Eggplant doesn't set fruit well when nights stay too warm or days are too hot. Low humidity, excess nitrogen, or poor pollination can also contribute.
• How to fix/prevent it: Be patient, as fruit set often resumes when temperatures moderate. Provide afternoon shade during extreme heat. Keep plants well-watered. Avoid excess nitrogen fertilizer. Try hand-pollination.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity can be a mixed bag for eggplant. The intense sun and dry air can stress plants, leading to blossom drop and pest problems. On the other hand, low humidity reduces the risk of fungal diseases. Consistent watering and afternoon shade are key to success here.

Good companions for eggplant in the Mountain West include green beans, peppers, spinach, and tomatoes. Green beans fix nitrogen in the soil, which can benefit eggplant. Peppers and tomatoes are also heavy feeders, so they thrive in similar conditions. Spinach provides ground cover, which helps to retain moisture and suppress weeds.

Avoid planting eggplant near fennel. Fennel inhibits the growth of many plants, including eggplant. Its allelopathic properties can stunt the growth and reduce the yield of your eggplant crop.