The technique for planting summer squashes, winter squashes, and pumpkins is the same. Grow all squashes on hills spaced 3 to 8 feet apart depending upon the leaf size–the larger the leaf the farther apart. Set seedlings started indoors in the garden as soon as the weather has warmed. Make sure squashes are large and strong before the end of June when squash beetles hit the garden. The larger and stronger the plant the better it will resist attack.
Plant summer squashes, winter squashes, and pumpkins all at the same time and the harvests will be staggered from midsummer to the first frost–summer squash in about 50 days, winter squash in about 85 to 100 days, and pumpkins after 100 or more days.
Summer and winter squashes and pumpkins
Squashes and pumpkins are members of the gourd family. Summer squashes and pumpkins originated in Mexico and Central America. Most winter squashes originated in or near the Andes in northern Argentina.
Summer squashes–zucchini, patty pans, and cocozelles (Italian for vegetable marrows)–have whitish or yellow flesh. They are the quickest to harvest–picked in summer while immature and as soon they are big enough to use.
Winter squashes have orange flesh. They take longer to mature than summer squashes. Harvest winter squashes when their skins are extremely hard and their stems have started to dry out.
Pumpkins–which are simply very large hard-skinned squashes that are usually orange–are the longest to harvest mostly because they are commonly carved at Halloween and pureed for Thanksgiving pie. Like other winter squashes, they are picked when their skins are extremely hard and their stems are dry.
Plant squashes and pumpkins when night temperatures no longer fall below 55°F and the soil is at least 60°F (seeds will not germinate in cold soil–the optimal soil temperature is 70°F). Prepare the planting site by digging a hole 18 inches wide and deep. Place 3 to 4 inches of aged compost or manure into the bottom of the hole and refill the hole with 3 parts soil and 1 part compost or manure. Create a planting hill about 4 inches high. Space the hills about 3 to 4 feet apart for bush squash and 8 feet or more apart for vining plants. Set 6 to 8 seeds evenly spaced on each mound. They will germinate in 7 to 14 days depending upon the variety. When plants are 3 inches tall thin to the two strongest seedlings (use scissors to thin rather than pulling plants up by the roots which can upend neighboring plants). Use cloches to protect cold-sensitive seedlings if frost threatens.
Protecting squash from cold
Floating row covers will protect squashes from dipping temperatures. If night temperatures fall below 65°F put the row covers in place. Row covers will also protect plants from early pests. When plants begin to flower (about three weeks after they have sprouted), remove the row covers to allow for pollination by bees and insects.
Water seedlings well, and keep the soil moist throughout the season; the roots need regular moisture. If plants look wilted before eleven o’clock in the morning, they need water. (Dig down in the soil; if the soil is dry at four inches down–water. If the soil is moist at three inches down, watering is good.) To avoid transmitting diseases, water at the base of each plant and keep the foliage dry. Leaf and fruit diseases are easily transmitted via wet foliage. Avoid handling plants when they are wet. It is not unusual for squash to wilt slightly on hot days.
Squashes are heavy feeders. Add plenty of aged compost or manure to the planting bed in advance of sowing. Before you plant, place aged compost or manure at the bottom of each planting hole and throw in a buffer inch or two of native soil. This will get plants off to a strong start. Apply compost tea or manure tea at transplanting or two weeks after seedlings emerge. Feed again with compost tea in three weeks or when the first flowers appear. When the first fruits set, water each plant with compost tea or side-dress each plant with a shovel full of compost. If leaves are pale, give plants a dose of fish emulsion. But be careful not to give squashes too much nitrogen; nitrogen will increase leafy growth but cut fruit yield.
Squash plants easily cross-pollinate. If you grow more than one type of squash in your garden, hand-pollination may be the best way to prevent cross-breeding. You can transfer pollen from the male stamen to the female pistil using a small brush or pick off the male flower and run the stamen against the female flower. Female flowers often blossom before male flowers appear. (Female flowers have a tiny fruit at their base.) If female flowers are not pollinated, they will dry up and fall off. Because squash plants are prolific bloomers, soon male flowers will appear to pollinate later female blossoms. As well, squash plants will sometimes abort small fruits when there is a heavy fruit set. This is a self-pruning process.
When vines grow to 5 feet, pinch off the growing tips to encourage fruit-bearing side-shoots. By midsummer, pinch off remaining flowers and small fruits on vining and winter squash. This will allow the plant to focus its energy on the ripening crop.
To avoid rot, put 6 inches of straw, hay, or dry leaves under fruit. Mulch when vines begin to lengthen. This will slow weed growth. Weeds compete with crops for water and nutrients. If the mulch gets wet, set a board or shingle under each fruit. Early in the season, black plastic can be used to mulch squashes. Black plastic helps warm the soil earlier and keeps it warm; this, in turn, can speed up the growth of squashes.
Harvest squashes when the weather is dry. Use a sharp knife to cut the fruit off the vine, leaving 3 to 4 inches of stem on the fruit. Harvest summer squash when the fruit is small to moderate size. Pick each fruit before the blossoms drop off the tip otherwise, the plant will quit producing. Pick winter squash and pumpkins when the rind is thick and hard and can not be penetrated by a thumbnail. Pick winter squashes and pumpkins before the first frost. Dry winter squashes (except acorn squash) in the sun until stems shrivel and turn gray; this will take about a week. Store winter squash in a cool, dry place with temperatures of 45° to 50°F and with 65 to 70 percent humidity.
More squash growing tips at How to Grow Squash.
More pumpkin grow tips at How to Grow Pumpkins.