Time to Plant
From the UC IPM section on when to plant tomatoes—Napa County home gardeners, please heed this guide, and avoid a little heartache!
In our North Coast area, defined by UC as north of Monterey County, sow seeds and start transplants INDOORS in March and April.
Resist the temptation to plant when you see tomatoes at the garden center and WAIT to direct seed or set out transplants in MAY. If you simply can't resist, be alert to weather conditions and protect tender young plants from frost.
Research from UC has shown that plants set in the ground in April and plants set out in May are the same size by June! That's because . . . .
Tomatoes are warm-weather plants. They like sunshine and produce best when planted in a well-exposed area in the garden. If you plant earlier, provide frost protection such as plastic jugs or covers that go over small plants. However, you can help prevent seedlings from damping off and diseases such as early blight by planting when the weather is warmer.
Trapping the heat from the sun during the day and slowing the re-radiation of that heat at night by using row cover helps protect tomato plants from varying temperatures during the springtime.
Tomatoes are suitable for a small garden if compact varieties are grown. Transplants, shoots, or roots are used for field planting.
Going forward, here is what to expect of your tomatoes regarding temperatures. Temperature (F) Comments 100° Flowers will not set 80°–90° Optimum growth 70°–80° Optimum germination 50°–55° Minimum night temperature for fruit set 45° Will grow slowly 32° Potential injury by frost.
For More information on this topic download this FREE UC ANR publication:
Growing Tomatoes in the Home Garden