Author: Carolyn Lynch, Inyo-Mono Master Gardener
Owens Valley offers ideal summer weather for growing delicious tomatoes. However, the high-desert climate also brings challenges, including temperature extremes, wind, low soil fertility, and a relatively short growing season.
To produce excellent tomatoes in this region, plants must start strong. The following recommendations come from the experiences of Master Gardeners working in local gardens and the Sunrise Research Garden in Bishop.
Know Your Soil
A soil test can help determine which amendments should be applied before planting. Contact local Master Gardeners for a list of soil-testing laboratories.
Local soils typically contain very little organic matter and benefit from generous additions of compost and other organic materials. Manure, leaves, and similar amendments are best incorporated in autumn so they can decompose during the winter.
For optimal production, fertilize tomato plants monthly once fruit begins to set.
Choose Early Varieties
Check the estimated number of days from transplanting to harvest (usually listed on seed packets or plant labels).
- 70 days or fewer is considered early.
- 60 days or fewer is considered very early.
Planting a few early varieties can extend the harvest season by a month or more while waiting for large heirloom varieties to mature.
For Owens Valley conditions, the listed “days to maturity” estimates are usually optimistic. Use them primarily to compare varieties rather than as exact predictions.
Select Healthy Seedlings
Choose large, actively growing seedlings.
When purchasing plants, select sturdy, bright green plants with roots that have not begun circling inside the pot or growing out through the drainage holes.
Starting Tomatoes from Seed
Growing tomatoes from seed is not difficult, but it requires time, attention, and adequate indoor space.
Seeds should be started in mid-March so plants are ready for transplanting once soil and air temperatures warm in May.
Important considerations include:
- Provide adequate warmth and strong light for seedlings.
- Transplant seedlings into larger containers as they grow.
If you can maintain plants in large containers (at least 1 gallon) as the outdoor season approaches, seeds may be started several weeks earlier.
However, starting too early can be counterproductive. Plants that outgrow their containers become root-bound, stop growing, and may lack vigor when transplanted into the garden.
Ensure Soil Is Warm Enough
Before transplanting, confirm that the soil is warm enough.
Use a soil or compost thermometer to measure temperature at the root zone (about 6 inches deep). Soil should be at least 60°F (16°C) before planting.
Tomatoes planted in colder soil will stop growing until temperatures rise, and soil-borne diseases may become a problem.
If seedlings become too large while waiting for soil to warm:
- Transplant them into larger pots.
- Keep them in a sunny location protected from freezing temperatures.
You can accelerate soil warming by:
- Installing soil-heating cables
- Covering soil with clear plastic sheeting (remove before planting)
- Placing Wall-O-Water plant protectors where tomatoes will be planted
Protect Plants from Wind and Frost
Young tomato stems are somewhat brittle and benefit from staking.
In Bishop, frost protection is typically necessary until at least the end of May.
Wall-O-Water plant protectors are recommended because they:
- Protect plants from both freezing temperatures and wind
- Last for many years
- Provide reliable early-season protection
Avoid Overwatering
Tomato roots require oxygen. When soil remains saturated, roots cannot access enough oxygen.
Observations from local gardens show that tomatoes grown in overly wet soil produce fruit that ripens slowly and often has poor flavor.
Typical watering guidelines:
- New transplants: may require daily watering.
- Established plants: deep watering 2–3 times per week is usually sufficient.
Observe your plants. If they are not wilting (aside from slight afternoon drooping during heat), they are receiving adequate water.
Mulching the garden helps:
- Maintain consistent soil moisture
- Reduce weed growth
Monitor for Pests and Diseases
If you suspect pest or disease problems, take action immediately.
For diagnostic help and management strategies, contact us via the helpline or consult the University of California Integrated Pest Management (UC IPM) website.
Additional Resources
For more detailed information on tomato cultivation, see:
UC ANR Publication 8159 — Growing Tomatoes in the Home Garden