Growing tomatoes can be done successfully in large or small vegetable gardens, raised beds, and patio containers. Wherever they’re planted, the earliest harvest comes from plants seeded indoors. While it is always tempting to plant them outdoors in early spring, it is not until May that the soil and air temperatures warm up enough to get tomatoes started properly, although conditions in some years are suitable after April 15. Cold spells at any time will slow fruit production.
Gardeners closer to the coast will find success with different varieties than gardeners inland where summer temperatures are much higher. When selecting varieties, keep in mind the length of your season, conditions of your microclimate, and how you are going to use your tomatoes—fresh or cooked.
Selecting a Tomato
- Plant early, mid-, and late-season varieties to pace production over many weeks.
- Choose either a determinate variety that grows to a certain height, tends to be bushy, and produces all fruit at one time; or choose an indeterminate variety that grows larger like a vine, does best with support, and will continually yield fruit all season.
- Look for disease-resistant varieties when purchasing seed or starts from nurseries.
- Prepare nutrient-rich, organic, well-drained soil with compost and a balanced fertilizer mixed into beds with clay or sandy soil.
- Start seed indoors in February; set out in the garden in May.
- To transplant, pinch off lower leaves, plant stems deeply, burying several inches of stem.
- Provide full sun, 6-8 or 10 hours a day.
- Mulch beds to help retain soil moisture, keep fruits clean, and suppress weeds.
- Fertilize with fish emulsion, kelp, or another natural fertilizer after fruits develop, then every month thereafter. Avoid high-nitrogen fertilizers that promote more leafy growth than fruits.
- Support plants with stakes or cages to lift vines off the ground, control their spread, keep foliage dry and fruit clean.
- Prune stems, if desired, to manage excess vining and encourage larger fruit size.
- Decrease water frequency as plants mature but keep root zone moist. Allow soil surface to dry out up to 1 in. deep. Take care not to over-water. Drip irrigation is most efficient.
Pest and Disease Management
- Reduce fruit rot by supporting plants off the ground.
- Apply water evenly and add calcium to garden beds to guard against blossom end rot.
- Avoid overhead watering; keep foliage dry to prevent fungal diseases.
- Hand pick any worms or insects that may appear.
- Rotate location of crops each year to prevent disease from soil-borne organisms.
- The Sonoma County Master Gardener Guide to Growing Tomatoes
- Sonoma County Master Gardener Vegetable Planting Summary.