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.
Irrigation water may have to be heated in the winter before use.
Water less than 50°F will chill the roots, causing poor growth. Plants
should be fertilized weekly with a starter solution (1/2 ounce of
21-53-0 per gallon of water) in the irrigation water. As plants become
larger, feeding can be increased to twice a week.
should be established in the ground beds approximately four to six
weeks after seeding. Set transplants in the soil 1 inch deeper than
previously grown. Space plants 15-18 inches apart in rows 3-3.5 feet
wide. Water immediately after transplanting.
should be trained as single (main) stems by removing all side shoots or
suckers that develop between leaf petioles and the stems. Remove shoots
by snapping them off, not cutting, as diseases can be transmitted on
the knife blade. Vines can be supported by plastic or binder twine
loosely anchored around the base of the plants (non-slip loop) and to
overhead support wires (11- to 12-gauge) running the length of the row.
Overhead wires should be at least 7 feet above the surface of the bed
and be firmly anchored to support structures.
should be wrapped clockwise around the vine as it develops, with one
complete swirl every three leaves. The vine should be supported by the
twine under the leaves, not the stems of the fruit clusters. Also wrap
twine in the same direction, using clips or tape to keep vines from
slipping down the twine. Do not try to wrap the twine around the growing
tip because the tip may break.
When plants reach overhead supporting wires, untie
the twine and lower vines and twine at least 3 feet. After lowering,
vines should all lean in one direction in one row. Vines in adjacent
rows should lean in the opposite direction. Retie twine with the vines
to the support wire. Be sure to leave at least 4-5 feet of extra twine
for this purpose when initially tying vines. Remove any leaves that lie
on the soil.
About 40-45 days before
terminating harvest, plants can be "topped" by pinching out the terminal
growing tip. Keep two leaves above the top flower cluster. Topping
vines will force remaining food reserves into maturing fruit already
present on the vines. Continue to remove any suckers that develop.
fruit mature on the lower part of the vine, pinch off older leaves
below the fruit. This will provide better air circulation, which helps
to reduce the incidence of disease and opens vines up for spraying and
Growers should remove any deformed,
immature fruit which will ultimately become culls. Removing excess
fruit also will result in larger tomatoes at harvest that can be sold at
a premium price.
pollination of tomato flowers is generally needed in the greenhouse due
to limited air movement and high humidity. An electric or
battery-powered vibrator can be used to vibrate flower clusters just
above the area where they originate from the stem. The vibration will
release pollen necessary for pollination. This can be done twice a day
(around 10:00 am and 3:00 pm). If tobacco mosaic virus has been a
problem, the vibrator should be wiped after each use with a clean cloth
or sponge moistened in a 5 percent chlorine solution. Because all
flowers on a cluster do not open at the same time, the same cluster will
have to be vibrated again as new flowers open. Air from a mist-blower
also has been found effective in pollinating tomatoes.
number of factors can result in poor fruit set. The most common problem
is temperature extremes (above 90°F during the daytime, above 75°F at
night, or below 57°F at night). Other adverse conditions include high
humidity, low light intensity, nutrient imbalances, pests, and water
pH for tomato production is 5.8-6.8. Depending on a soil analysis,
phosphorous should be applied pre-plant incorporated at a rate of
200-400 lb/a of P2O5. Soils deficient in potassium may require similar
quantities of potassium (K20). Both the phosphorous
(treble-superphosphate) and potassium (potassium sulfate) should be
incorporated to a depth of 8-12 inches. Approximately 50 lb/a of
elemental nitrogen should be applied before planting. Additional
nitrogen can be applied as a sidedressing or through the irrigation
system as needed. Leaf analysis is the best way to determine additional
nutrient requirements. Plants exhibiting deficiencies of minor elements
such as iron or zinc can be treated with foliar applications of iron or
zinc sulfates or chelates.
mulch of clean straw can be placed around plants to a depth of 3-4
inches. Mulches will help conserve moisture and keep soil from
compacting between plants. Mulches are most effective when used in
combination with drip irrigation.
should remain on the vine for as long as possible for maximum quality.
However, market specifications will determine whether fruit should be
harvested earlier (light red stage). Plants are generally harvested two
to three times a week. Fruit should be snapped from the plant leaving a
small portion of the pedicel and green calyx bracts attached to the
fruit, a distinct trademark for greenhouse-grown tomatoes.
should be graded using USDA standards. Most buyers prefer U.S. No. 1
fruit. The best market for greenhouse-grown tomatoes in New Mexico is
between November and April.
Ripe fruit should
be cooled to 55°F for maximum shelf life, but never allow the
temperature to drop below 50°F. Light-colored fruit can be held at 70°F
until the desired color is achieved.
tomatoes are generally marketed in 8- to 10-pound baskets or cartons.
Some two-layered cartons may hold 16-20 pounds of fruit. Cartons should
be sturdy enough to prevent mechanical damage when handling. Fruit and
packaging should be distinctly labeled with decals or other
identification to distinguish them as greenhouse-grown tomatoes.
- very popular; very firm, large, red fruited type (8-9 oz);
resistance1 to Fusarium wilt (race 1), Verticillium wilt, early blight,
gray leaf spot, and some leaf molds; tolerance1 to blotching and some
races of tobacco mosaic virus (TMV).
'Jumbo' - similar to
'Tropic'; excellent yields; more USDA #1 fruit (8 oz); resistance to
Fusarium wilt (races 1 and 2) and Verticillium wilt; not resistant to
'Floradel' - 6-oz fruit; resistance to Fusarium wilt, gray leaf spot, and some leaf molds.
- excellent fruit quality and color; vigorous and productive plants;
medium-size fruit; resistance to Fusarium wilt and gray leaf mold;
resistance to fruit cracking.
'Vendor' - develops good red
color; medium-large fruit (4-8 oz); uniform ripening fruit; moderately
firm; resistance to TMV (race 1), Fusarium wilt, and several races of
leaf mold; fruit resist cracking.
'Pole King' - 8- to 9-oz fruit; sturdy vines; resistance to Fusarium and Verticillium wilts.
hybrid - medium-large fruit (8 oz); resistance to Fusarium and
Verticillium wilts; adapted to low light conditions.
O and V' - excellent fruit quality and color; very productive; small to
medium-size fruit; minimal fruit cracking; resistance to leaf mold (one
strain) and Fusarium wilt.
'Trend' - high yield potential; large, smooth, red fruit; good crack tolerance; resistant to Fusarium crown rot.
'Furon' - red, medium size, beef-steak type; good tolerance to cracking and russeting; resistant to Fusarium crown rot.
Cherry Gold' - golden-yellow cherry type; vigorous vines up to 6 ft
long; more compact and larger fruit than other cherry varieties;
resistance/tolerance to Verticillium and Fusarium wilts.
Diseases are best controlled through prevention. Selecting a sunny site
with a well-drained soil, sterilizing the soil, providing good air
circulation, and monitoring your irrigation closely will help keep
diseases to a minimum. Nevertheless, keep a good supply of recommended
fungicides on hand with an appropriate sprayer that will effectively
cover all plant surfaces.
include seed rot (failure of seed to germinate due to fungi), stem rot,
and pre- and post-emergence damping-off. Damping-off refers to the
attack of seedlings before and after emergence from the soil. Symptoms
include the development of dry or water-soaked lesions at the soil line,
resulting in stem constriction and plants toppling over. Seedling
diseases are most commonly caused by soil-borne fungi like Pythium spp.
and Rhizoctonia solani. Soil sterilization, seed treatment with
appropriate fungicides, and good cultural practices are the most common
Root-knot nematodes cause
plants to become stunted and wilt (diurnal wilting is common). Roots
develop knots, galls, or swelling. Secondary symptoms of nutrient
deficiencies may result from the inability of roots to take up the
necessary nutrients. Soil sterilization is the most effective control
Verticillium and Fusarium wilts cause
leaves to become yellow along the margins and between veins. Plants
become stunted and wilt severely during the day, but recover at night.
Eventually the entire plant dies. Vascular tissue is streaked brown
(streaking occurs high on the stem and into petiole scars with Fusarium
wilt, and occurs on lower stems and is not evident in petiole scars with
Verticillium wilt). For best control, use soil sterilization and plant
Leaf mold (Fulvia fulva =
Cladosporium fulvum) is the most common and destructive disease in
greenhouse-grown tomatoes, and is particularly severe under conditions
of high humidity. Lower leaves develop pale green spots on their upper
surfaces and eventually turn yellow; spots become covered with patches
of olive-green to brown mold on the bottoms of leaves. Maintaining
humidity below 90 percent by providing good air circulation will help
control this disease. Use appropriate fungicides, resistant varieties,
and soil sterilization for maximum results.
mold (Botrytis cinerea) is a grayish, powdery, moldy growth on fruit,
leaves, and stems. Use similar control measures as for leaf mold;
resistant varieties are unavailable.
blight (Alternaria solani), which may occur at any time in the season,
causes collar rot of seedlings and spotting on leaves and fruit. Note
that concentric rings on leaves create a target pattern. Use similar
controls as for leaf mold.
(Pseudomonas solanacearum) causes diseased plants to wilt and die
rapidly (with no yellowing or leaf necrosis). The pith in the stem near
the soil line will become water-soaked and dark. Best controls include
good sanitation and soil sterilization.
mosaic virus (TMV) disease reduces fruit set and quality. A mosaic or
mottled appearance of the leaves is the most common symptom. Plants
infected as seedlings are usually stunted and slightly yellow; the
leaves also may be curled, small, or deformed. Greenhouse workers should
wash their hands carefully with soap and water after using tobacco
products. Remove any diseased plants as they appear.
rots are caused by fungi like Alternaria, Phytophthora, and Botrytis.
Maintaining optimum temperature and humidity are critical for good
control. Use of registered fungicides can help to reduce the incidence
and severity of fruit rots as can good greenhouse sanitation. Handle
fruit carefully to prevent bruising.
diseases that can cause problems with greenhouse-grown tomatoes are
blossom-end rot and sunscald. Blossom-end rot occurs when tomatoes are
stressed for water and calcium, resulting in the formation of a sunken,
brown, leathery spot on the blossom-end of the fruit. Monitoring soil
moisture and mulches will help prevent this problem. Over-exposure of
the fruit to sun can result in sunscald. Training of vines and leaves to
cover developing fruit should solve this problem.
Aphids are small, soft-bodied insects that insert piercing-sucking
mouth parts into tomato plants to extract plant juices. Heavy
populations can cause leaf curling and plant stunting. Aphids also serve
as vectors for several plant diseases. Sticky honeydew produced by
aphids may result in growth of black sooty mold.
adults are small, winged, white insects 1/16" long. They suck juices
from plants and, like aphids, whiteflies are vectors for some diseases.
Honeydew produced by whiteflies also will support growth of black sooty
Thrips are very small insects with
piercing-sucking mouth parts that feed on plant juices. They can spread
tomato spotted wilt viruses and cause premature blossom drop.
mites are non-insect pests (related to spiders) that feed on plant
juices on underside of leaves. Leaves may become stippled (gray) and
covered with a fine web; defoliation can occur with heavy infestations.
Mites are yellowish to greenish with a dark spot on either side.
insect and non-insect pests that can cause occasional problems include
cutworms, earwigs, snails, slugs, and various caterpillars. Sanitation,
soil sterilization, screens on ventilation fans, and appropriate
insecticides should be used for maximum control of pests.