Eggplant in Zone 8A — Pacific Northwest

Eggplant might seem like a stretch in the Pacific Northwest, but the taste of homegrown fruit, grilled or in ratatouille, makes it worth the effort. Plus, the satisfaction of coaxing a warm-season crop to thrive in our mild summers is uniquely rewarding.

While we don't have the scorching heat of other regions, our long growing season and cool nights actually benefit eggplant flavor. You can absolutely grow eggplant here with a little planning, starting seeds indoors, and choosing the right varieties. Our 203-day growing season gives you time to get a harvest.

Since our springs can be cool and eggplant needs warm soil, starting seeds indoors is essential in the PNW. Begin your seeds indoors from late February through mid March, about eight weeks before you plan to transplant them outside. You'll need seed trays, a heat mat to keep the soil around 80-85°F, and a grow light to prevent leggy seedlings during our overcast spring days.

Bottom watering is key. Place your seed trays in a shallow tray of water and let the soil soak it up from the bottom. This encourages strong root growth and prevents damping off. Remember, our springs are slow to warm up, so giving your eggplant seedlings a head start indoors is crucial for success.

Transplant your eggplant seedlings outdoors from early to late May, after the danger of frost has passed and the soil has warmed up to at least 65°F. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This prevents transplant shock.

Plant your eggplant 18-24 inches apart in a sunny spot. Be mindful of late spring showers and unexpected cool snaps. If a cold spell threatens, protect your young plants with row covers or cloches.

Eggplant needs consistent moisture to thrive, especially during our dry summer months. Aim for about 1-2 inches of water per week, but adjust based on rainfall and soil conditions. The "finger test" is a good guide: stick your finger about 2 inches into the soil; if it feels dry, it's time to water.

Water deeply at the base of the plant rather than overhead, which can encourage fungal diseases. Because our humidity is low during the summer, overhead watering isn't as much of a concern, but it's still best to water the soil directly. Signs of underwatering include wilting leaves and small, bitter fruit. Overwatering can lead to yellowing leaves and root rot.

Mulching around your eggplant with straw or compost helps retain moisture and suppress weeds. This is especially helpful during our dry summer months when you need to conserve water.

Eggplant branches can get heavy with fruit, so providing support is important to keep the plants upright and prevent the fruit from touching the soil. Staking is the most common and effective method.

Install a sturdy stake near each plant at transplant time, driving it a few inches into the ground. As the eggplant grows, gently tie the main stem to the stake with soft twine or plant ties. This will help support the weight of the fruit and prevent branches from breaking.

Eggplant requires minimal pruning, but a little attention can improve airflow and fruit production. Remove any suckers (small shoots) that grow below the first main fork of the plant. These suckers steal energy from the main plant and reduce fruit yield.

During the growing season, limit the plant to 5-6 main branches to encourage larger fruit. As the end of the season approaches (late October in the PNW), you can remove any new flowers to direct the plant's energy into ripening the existing fruit before the first frost.

You can expect your first eggplant harvest from early July through late August, about 70 days after transplanting. Look for fruit with glossy skin and a slight give when pressed gently. Dull skin indicates that the eggplant is overripe and may be seedy.

Use a sharp knife or pruners to cut the fruit from the plant, leaving a short stem attached. Avoid pulling the fruit, which can damage the plant. Regular harvesting encourages continued production throughout the season.

As the first frost approaches in late October, harvest any remaining eggplant, even if they are not fully ripe. Smaller fruit can still be used in cooking.

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. You'll see small, dark beetles that jump when disturbed. The worst damage occurs to young seedlings.
• What causes it: These small jumping beetles feed on leaves, causing damage, especially to small, young plants.
• How to fix/prevent it: Row covers protect seedlings during their vulnerable stage. Delay planting until plants are larger and more resilient. Kaolin clay coating and neem oil spray can also help. Interplanting with basil or catnip may deter them. Healthy, vigorous plants often outgrow the damage.

Colorado Potato Beetle

• What it looks like: Yellow and black striped beetles and orange larvae feeding on leaves, causing significant defoliation.
• What causes it: Beetles and larvae feed on leaves, causing significant damage. They are particularly attracted to plants in the nightshade family.
• How to fix/prevent it: Handpick beetles and larvae regularly. Apply Bacillus thuringiensis (Bt) specifically for Colorado potato beetles. Rotate crops to disrupt their life cycle.

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 a stem cross-section.
• What causes it: A soil-borne fungus that persists for years. Cooler soil temperatures favor it in the PNW, unlike fusarium. It has a wide host range.
• How to fix/prevent it: There's no cure, so remove infected plants promptly. 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. Eggplant doesn't set fruit well when nights stay above 75°F or days exceed 95°F. It can also be caused by low humidity, excess nitrogen, or poor pollination.
• How to fix/prevent it: Be patient; fruit set typically resumes when temperatures moderate. Provide afternoon shade during extreme heat. Keep plants well-watered. Avoid excess nitrogen fertilizer. Try hand-pollination to ensure fruit set.

Pacific Northwest Specific Challenges: Late blight is less of a concern for eggplant than tomatoes, but good air circulation helps. Cool spring soil can stress plants, making them more susceptible to wilt. Our mild summer heat can sometimes lead to blossom drop, so provide shade during the hottest part of the day. Slugs can be a problem for young plants, so use slug bait or traps.

Good companions for eggplant in the Pacific Northwest include green beans, peppers, spinach, and tomatoes. Green beans fix nitrogen in the soil, benefiting eggplant growth. Peppers and tomatoes, being in the same family, thrive in similar conditions and can be planted near eggplant. Spinach provides ground cover, suppressing weeds and keeping the soil cool.

Avoid planting fennel near eggplant. Fennel inhibits the growth of many plants, including eggplant.