Eggplant in Zone 6B — Mountain West

Eggplant might seem like a Mediterranean crop, but with a little planning, you can absolutely enjoy its rich, savory flavor in your Mountain West garden. Imagine grilling slices of your own homegrown eggplant, the cool mountain air enhancing its taste. The satisfaction of harvesting these beauties after nurturing them through our unique climate is truly rewarding.

Our high altitude, intense sun, and short growing season present unique challenges for eggplant. But don't worry! By starting indoors and timing your transplant carefully, you can take advantage of our 163-day growing season and the intense sunlight that, while harsh, promotes excellent flavor development.

Starting eggplant indoors is essential in our region to get a head start on the short season. Begin your seeds indoors from mid March through early April, about 8 weeks before you plan to transplant them outside. Use seed trays with a good quality seed-starting mix.

Eggplants need warmth to germinate, so aim for a soil temperature around 80-90°F. A heat mat can be a lifesaver. Once the seedlings emerge, they need plenty of light. A grow light is highly recommended, especially considering our late spring starts.

Bottom watering is a great way to keep the soil consistently moist without damping off. Place the seed tray in a shallow dish of water and let the soil soak it up from the bottom. Remember, our springs can be cool and unpredictable, so indoor starts are non-negotiable for eggplant success.

Transplant your eggplant seedlings outdoors from mid May through mid June, once the danger of frost has passed and the soil has warmed up. Before transplanting, you'll want to harden off your seedlings. This means gradually exposing them to outdoor conditions over about a week.

Start by placing them in a sheltered spot for a few hours each day, increasing the time and sun exposure gradually. Space your plants 18-24 inches apart in a sunny location.

Keep an eye on the weather forecast around transplant time. A late frost can still happen, so be ready to cover your plants if needed. Waiting for the soil to warm up is key, as cold soil can stunt their growth.

Eggplant needs consistent moisture to produce its best fruit, especially in our dry Mountain West climate. Aim to keep the soil consistently moist, but not waterlogged. The "finger test" is a great way to check. Stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

During the peak of summer, your eggplants will likely need about 1-2 inches of water per week. Because of our low humidity, watering at the base of the plant is ideal to avoid fungal diseases.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants helps retain moisture and keeps the soil cooler, which is especially beneficial in our intense sun.

Eggplant branches can become heavy with fruit, causing them to droop or even break. Providing support is crucial for healthy plants and a good harvest. A simple stake works wonders.

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 using soft twine or plant ties.

Check the ties regularly and adjust them as needed to prevent the plant from being constricted. By keeping the fruit off the ground, you also reduce the risk of pests and diseases.

Eggplant benefits from minimal pruning to encourage airflow and larger fruit. Remove any suckers that grow below the first main fork of the plant. These suckers will only steal energy from the main branches.

Throughout the season, you can also limit the plant to 5-6 main branches to encourage larger fruit size. In the late season, as the first frost approaches in early October, you can pinch off any new flowers to direct the plant's energy into ripening existing fruit.

Don't over-prune, as eggplant leaves provide shade for the developing fruit, protecting them from sunburn in our intense UV.

You can expect your first eggplant harvest from late July through mid September, depending on the variety and the weather. Eggplant is ready to harvest when the skin is glossy and firm, with a slight give when pressed gently. Dull skin indicates that the fruit is overripe and may be seedy.

Use a sharp knife or pruning shears to cut the fruit from the plant, leaving about an inch of stem attached. Pulling the fruit can damage the plant. Eggplant is a continuous harvest crop, meaning it will continue to produce fruit throughout the season if you harvest regularly.

As the first frost approaches in early October, harvest any remaining mature fruit, even if they are not fully ripe. They can often be ripened indoors. Smaller, immature fruit are unlikely to ripen fully.

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

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. Small dark beetles that jump when disturbed. Worst damage to young seedlings.
• What causes it: Small jumping beetles that feed on leaves. Most damaging to small, young plants.
• How to fix/prevent it: Row covers protect seedlings during vulnerable stage. Delay planting until plants are larger. Kaolin clay coating. Neem oil spray. Interplant with basil or catnip. Healthy, vigorous plants outgrow damage.

Colorado Potato Beetle

• What it looks like: Yellow and black striped beetles and orange larvae feeding on leaves. Defoliation of plants.
• What causes it: Beetles overwinter in the soil and emerge in spring to feed on plants.
• How to fix/prevent it: Handpick beetles and larvae. Row covers can protect young plants. Insecticidal soap or neem oil can be effective. Crop rotation.

Verticillium Wilt

• What it looks like: Lower leaves yellow, wilt, and die, progressing upward. One side of plant may be affected first. Brown streaks in stem cross-section.
• What causes it: Soil-borne fungus that persists for years. Cooler soil temperatures favor it.
• How to fix/prevent it: No cure — remove infected plants. Rotate with non-susceptible crops (corn, grains). Solarize soil. 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. Plant looks healthy but produces no fruit.
• What causes it: Temperature stress. Eggplants don't set fruit well when nights are too cool or days are too hot. Also caused by low humidity, excess nitrogen, or poor pollination.
• How to fix/prevent it: Be patient — fruit set resumes when temperatures moderate. Provide afternoon shade during extreme heat. Keep plants well-watered. Avoid excess nitrogen. Try hand-pollination.

Mountain West Specific Challenges: Our moderate-at-altitude summer heat, combined with low humidity and dry rainfall, can make blossom drop a common issue. Consistent watering and providing afternoon shade during the hottest days can help. The intense UV can also cause sunburn on the fruit if the plants are not properly shaded by their leaves.

Companion planting can help your eggplant thrive in our Mountain West gardens. Green beans are a great companion because they fix nitrogen in the soil, which eggplant loves. Peppers and tomatoes also make good companions, as they have similar growing requirements and can benefit from shared support structures. Spinach can be planted as a ground cover to help retain moisture and suppress weeds.

Avoid planting fennel near eggplant, as it inhibits the growth of many plants. By choosing the right companions, you can create a thriving ecosystem in your garden and boost your eggplant yield.