Eggplant in Zone 7B — Pacific Northwest

Eggplant, with its rich flavor and versatility, is a rewarding addition to any Pacific Northwest garden. Imagine grilling slices with your favorite herbs, adding it to hearty ratatouille, or enjoying a smoky baba ghanoush made with your own homegrown produce. The cool nights we experience here actually enhance the flavor of many vegetables, eggplant included.

While eggplant isn't the easiest crop for our region, don't be discouraged. With a little planning and attention to timing, you can absolutely harvest beautiful, glossy fruit. Our 193-day growing season is just long enough if you give your plants a head start indoors and choose varieties that mature quickly.

Starting eggplant indoors is the key to success in the PNW. You'll want to sow your seeds indoors from early to late March, roughly 8 weeks before you intend to transplant them outside. Use seed trays with a good seed-starting mix, and provide consistent warmth – ideally 80-85°F – using a heat mat.

Eggplant needs plenty of light, so a grow light is essential, especially with our often overcast spring days. Keep the soil consistently moist, and consider bottom watering to prevent damping off. This involves setting the seed tray in a shallow dish of water, allowing the soil to soak it up from the bottom.

Transplant your eggplant seedlings outdoors from early May through early June, once the soil has warmed up. Be sure to harden them off for about a week beforehand by gradually exposing them to outdoor conditions. Start with an hour or two of shade, increasing the time and sun exposure each day.

Space your plants 18-24 inches apart in a sunny spot. Keep an eye on the weather forecast – late frosts can still happen in early May, so be ready to cover your seedlings if needed. Remember, our soil takes a while to warm up in the spring, so be patient and wait for consistently warmer temperatures.

Eggplant needs consistent moisture, especially during our dry summer months. Aim to water deeply but infrequently, providing about 1-2 inches of water per week, depending on rainfall. Use the "finger test" – stick your finger about 2 inches into the soil; if it feels dry, it's time to water.

Water at the base of the plant to avoid wetting the foliage, as this can encourage fungal diseases in our sometimes humid springs. During our dry summers, overhead watering is less of a concern. Signs of underwatering include wilting leaves and blossom drop, while overwatering can lead to yellowing leaves and root rot.

A good layer of mulch, like straw or compost, will help retain moisture in the soil, suppress weeds, and keep the soil temperature consistent. This is especially helpful during our mild summers, as it prevents the soil from drying out too quickly.

Eggplant benefits from support, especially when laden with fruit. A sturdy stake is usually sufficient. As the plant grows, tie the main stem to the stake with soft twine or plant ties.

Install the stake at planting time to avoid disturbing the roots later. This will help keep the plant upright, prevent branches from breaking under the weight of the fruit, and keep the fruit off the ground, reducing the risk of rot.

Eggplant requires minimal pruning. Remove any suckers (small shoots) that grow below the first main fork of the plant. This encourages better airflow and focuses the plant's energy on fruit production.

Later in the season, you can limit the plant to 5-6 main branches to encourage larger fruit. As the first frost approaches in late October, remove any small, immature fruit to encourage the plant to put its remaining energy into ripening the larger ones.

You can expect your first eggplant harvest from mid July through early September, depending on the variety and the weather. The best indicator of ripeness is the skin: it should be glossy and have a slight give when you gently press it. Dull skin indicates that the eggplant is overripe and may be seedy.

Use a sharp knife or pruners to cut the eggplant from the plant, leaving a short stem attached. Pulling the fruit can damage the plant. Regular harvesting encourages continued production, so check your plants frequently.

As the first frost approaches in late October, harvest any remaining mature fruit. Smaller, immature fruit can be brought indoors to ripen, but they may not develop the same flavor as those ripened on the plant.

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 is to young seedlings.
• What causes it: These are small jumping beetles that feed on the leaves. They are most damaging to small, young plants.
• How to fix/prevent it: Row covers protect seedlings during their vulnerable stage. Delay planting until plants are larger. Kaolin clay coating and neem oil spray can help. Interplant with basil or catnip. 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, causing defoliation.
• What causes it: Beetles overwinter in the soil and emerge in spring to feed and lay eggs on eggplant leaves.
• How to fix/prevent it: Handpick beetles and larvae. Use row covers to protect young plants. Insecticidal soap or neem oil can be effective against larvae. Rotate crops to disrupt the beetle's 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 may see brown streaks in a stem cross-section.
• What causes it: This is a soil-borne fungus that persists for years. Cooler soil temperatures favor it. It has a wide host range.
• How to fix/prevent it: There is no cure. Remove infected plants. Rotate with non-susceptible crops (corn, grains). You can solarize the 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. 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. 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.

Pacific Northwest Specific Challenges: While we avoid the extreme heat that causes blossom drop in other regions, our cool soil in spring can make eggplant more susceptible to verticillium wilt. Late blight, while more common on tomatoes, can occasionally affect eggplant, so maintain good air circulation and avoid overhead watering if possible. Slugs are always a problem in the PNW, so protect young seedlings with slug bait or traps.

Good companion plants for eggplant include beans-green, which fix nitrogen in the soil, benefiting the eggplant's growth. Pepper, tomato, and eggplant are in the same family and have similar needs, so they thrive together. Spinach can act as a ground cover, suppressing weeds and keeping the soil cool.

Avoid planting fennel near eggplant, as it inhibits the growth of many vegetables. Its strong aroma can also attract unwanted pests. By choosing the right companions, you can create a thriving and productive garden ecosystem, even in the unique climate of the Pacific Northwest.