One or two tomato crops can be planted in
the greenhouse during the year. Planting, transplanting, and harvest
dates will vary depending on location. As most tomato varieties will
begin to ripen 100 days after planting, seed should be planted so the
fruit begin to ripen soon after first frost for fall crops.
cooler areas of New Mexico, tomato crops are generally planted in early
July and transplanted to greenhouse beds in mid-August. Harvest will
begin in October and may continue until early March. Harvesting may be
terminated at an earlier date if heating costs become extreme. Late
spring harvest can be accomplished by delaying planting until late fall
or early winter. Planting dates in southern New Mexico should be delayed
until mid-August or later due to hot weather in mid-summer.
are best started in individual containers (plastic pots, peat pots, or
cubes) to reduce labor costs and reduce transplanting shock. Use of
commercial sterile potting mixes will decrease the incidence of seedling
disease problems. Custom soil mixes can be used, but must be
pasteurized to eliminate insects, diseases, and weed seed. Heating the
moist soil mixture to a temperature of 160°F for 30 minutes will kill
Sow two to three seeds per pot
(1/4-inch deep) and water. Then cover pots with clear polyethylene and
place in the shade (70°F) until seedlings emerge. Plastic should then be
removed and the pots moved into full sun. Thin the seedlings to one
plant per pot.
If possible, seedlings should be
grown at daytime temperatures of 58-60°F (nighttime 52-56°F) for the
first 10-14 days. This initial cold treatment should help seedlings
develop larger cotyledons and thicker stems. Plants should also set more
early fruit, increasing both early and total yields. Thereafter a
daytime temperature of 70-75°F (nighttime 60-62°F) should be maintained.
After the initial cold treatment, temperatures should not fall below
55°F, which may cause rough, irregularly shaped fruit and stunted plant
growth. Temperatures can be reduced slightly during cloudy days.