Vegetable Guide
Growing Tomatoes in a Screenhouse in Hawaii
Wailupe Farms
Waimanalo, Oahu
Updated 2026
Ask any experienced farmer in Hawaii and they'll tell you the same thing: growing tomatoes in the open field here is a losing battle. Whiteflies, sooty mold, and fungal disease will beat you every time. At Wailupe Farms, we only grow tomatoes under a screenhouse — and here's everything we've learned about making it work.
Hawaii has three major strikes against open-field tomatoes that make protected growing essentially mandatory for consistent production:
This is the big one. The silverleaf whitefly is the primary pest vector for tomato yellow leaf curl virus (TYLCV) and other devastating tomato viruses. Whitefly populations in Hawaii are enormous, year-round, and resistant to many conventional pesticides. In the open field, a tomato crop can be wiped out within weeks. A properly screened house with 50-mesh or finer screen blocks the whiteflies entirely.
Hawaii's constant humidity and frequent rain — especially on the windward side — creates perfect conditions for early blight, late blight, and powdery mildew. A screenhouse dramatically reduces foliar wetting, controls humidity to some degree, and keeps soil splash (a major disease vector) off lower leaves.
Trade winds and seasonal storms batter open-field tomatoes. A screenhouse gives physical protection, letting you stake vertically without the vines getting shredded.
Not all tomato varieties handle Hawaii's heat and humidity equally. Focus on varieties bred for tropical or subtropical conditions with known disease resistance.
Heirloom varieties with no disease resistance (Brandywine, Cherokee Purple, etc.) will disappoint in Hawaii's conditions. Save those for cooler, drier environments — or very controlled screenhouse conditions with aggressive IPM. For commercial production, stick with proven hybrids.
The screenhouse is your biggest investment and your most important tool. Get it right and everything downstream is easier.
Start seeds in trays outside the screenhouse (or in a separate nursery area). Harden off transplants before moving them in. Transplant into the screenhouse when seedlings are 4–6 inches tall with 2–3 true leaves — typically 3–4 weeks from germination.
For vertically trained indeterminate varieties: 24–36 inches in-row, 48–60 inches between rows. This seems generous but airflow between plants is critical for disease prevention inside an enclosed structure. Crowded plants = disease.
One of the big advantages of screenhouse production in Hawaii is year-round growing. Plant a new batch every 8–10 weeks to maintain continuous harvest. Stagger planting so you always have plants at different stages.
Indeterminate tomatoes in a screenhouse are trained vertically — this maximizes space, improves airflow, and makes pest management much easier than sprawling plants.
We use overhead wire systems with twine dropped down to each plant. As the plant grows, wind the twine around the stem every 6–8 inches, or use tomato clips. Remove all suckers below the first flower cluster — single-stem or two-stem training works best in tight screenhouse spacing.
Remove lower leaves as the plant grows — any leaf that's shaded or touching the ground is a disease entry point. Aim to maintain the bottom 12–18 inches of stem completely bare as the plant matures.
Drip irrigation is the gold standard for screenhouse tomatoes. It keeps water off foliage (reducing disease), delivers moisture consistently at the root zone, and can be set on timers to eliminate the labor of daily hand watering.
Calcium deficiency (causing blossom end rot) is common in fast-growing screenhouse tomatoes. Foliar calcium spray every 2 weeks during fruiting prevents it. Consistent soil moisture also reduces the plant's calcium uptake issues.
This catches many first-time screenhouse growers off guard. Tomatoes are self-pollinating but rely on vibration (from wind or bees) to release pollen. Inside a sealed screenhouse, there's no wind and — importantly — no bees.
A well-sealed screenhouse dramatically reduces pest pressure — but doesn't eliminate it. Be vigilant from day one.
If you see whiteflies inside, find and seal the entry point immediately. Yellow sticky traps placed throughout the screenhouse act as early warning systems and help control small populations. If whiteflies establish inside, biological control with Encarsia formosa (a parasitic wasp) is effective and doesn't require chemical intervention.
These can sneak in as moths and lay eggs. Check undersides of leaves regularly. Hand-pick caterpillars. Bacillus thuringiensis (Bt) spray is highly effective and safe.
More common inside enclosed structures, especially during hot dry spells. Look for fine webbing and stippled leaves. Predatory mites (Phytoseiulus persimilis) are an excellent biocontrol option. Avoid broad-spectrum pesticides that kill the predators.
Even inside a screenhouse, humidity can cause fungal issues. Lower planting density, remove diseased leaves immediately, and ensure airflow. Copper-based fungicides and neem oil are effective preventive sprays.
Pick tomatoes when they're fully colored but still firm — they'll continue to ripen off the vine. In Hawaii's heat, tomatoes left on the vine too long soften quickly. Harvest every 2–3 days once production starts.
Store at room temperature, never in the refrigerator — cold kills tomato flavor. Countertop or a cool shaded area is ideal. For restaurant or market sales, harvest slightly underripe for longer shelf life.