Time for Tomatoes

It’s that time of year again. Those of us who have the time and inclination are preparing for our gardens. What’s almost universal in every garden are tomatoes.

To grow successful tomatoes, consider factors like soil preparation, sun exposure, planting time, and support systems. In warmer regions, you can plant multiple rounds of tomatoes for a longer harvest season. In cooler regions, it's best to start seedlings indoors in March or April and transplant them outdoors after the last frost.

In the Bay Area, 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’s usually not until May that the soil and air temperatures warm up enough to get tomatoes started properly—though some years conditions 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.

Plant early-season, mid-season, 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 seeds 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.

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.

Here's a more detailed look:

Soil Preparation: Tomatoes thrive in well-drained, fertile soil. Amend with compost to improve drainage and nutrient content. Avoid using too much nitrogen fertilizer, as it can lead to excessive foliage at the expense of fruit.

Sun Exposure and Site Selection: Tomatoes need at least six to eight hours of direct sunlight daily. Choose a location that protects plants from strong winds and harsh afternoon sun, especially in hotter regions.

Planting Time: Again, you can plant tomatoes in early spring (March-April) and again in late spring/early summer (June) for a longer harvest.

In cooler regions, wait until after the last frost (typically late April or May) to plant seedlings outdoors. You can start seedlings indoors 5-7 weeks before the last frost date.

Support Systems: Tomatoes, especially indeterminate varieties, need support to keep them from sprawling on the ground and to improve air circulation. Use stakes, cages, or trellises to support the plants.

Water and Fertilization: Water tomatoes regularly, especially during dry spells, but avoid overwatering. Fertilize tomato plants with a balanced fertilizer after they have set fruit.

Pruning and Suckering: Prune suckers (new shoots that grow from the base of the main stem) to direct the plant's energy to the main fruiting branches. Prune out any branches that are not bearing fruit to improve air circulation.

Pest and Disease Control: Regularly inspect plants for signs of pests and diseases, such as powdery mildew or blight. Use organic pest control methods and consider using disease-resistant varieties.

Harvesting: Harvest tomatoes when they are fully colored and ripe. Store ripe tomatoes at 55-70°F to maintain flavor.