How to Grow Squash

Difficulty: All squash are easy to grow if you can provide enough space in full sun. All squashes have very large root systems, so none are particularly suited to container growing. Allow 10-20 square feet per plant.

Timing: Direct sow or transplant in late May or early June when soil is warm.

Sowing: Build up a small hill of soil, and sow 3 to 5 seeds per hill, 2cm (1”) deep. Thin to the best looking plant by cutting, not pulling, so as not to disturb the roots.

Spacing: Summer Squash: Rows 1—2.4m (3—4′) apart with plants spaced 45—60cm (18—24”) apart. Even the bush summer squash are big plants and most gardens do not need more than 2 or 3. You need to leave room so you can get to the plants to harvest them regularly. Winter Squash: Rows 1.2—1.8m (4—6′); space plants 45—60cm (18—24”). Farm: 100′ Row: 14—28g. Acre: 1—2kg (2—4lb). Rows: 1.8—2.4m (6—8′) apart; space plants 90cm (36”) apart. Winter squash are even bigger plants and many are vines. They can be set at the edge of the garden, so that the vines go across the lawn or path.

Soil: These big plants need lots of food! Use one cup of complete organic fertilizer under each plant. Do not water until after the plants are established. Like other flowering or fruiting plants, these require full sun. Add ample organic matter to the planting site to retain moisture, and aim for a pH range of 6.0 to 6.5.

Growing: All squash grow male flowers first then the female flowers are produced. The female flowers have tiny fruits at the base of the petals and require pollination by bees mostly. Incomplete pollination often happens at the beginning of the season, and results in misshapen fruit at the flower end. Just discard these damaged fruit. You can encourage bees to your garden by planting Buckwheat and/or Phacelia. For the largest pumpkins, grow only one fruit per plant by removing all female flowers once you can verify that a fruit is forming. Gradually adjust the fruit so that is growing perpendicular to the vine. Feed the plants every two weeks with a fish-based liquid fertilizer.

Harvest: Summer squash become blander as they mature, so aim to harvest very young fruits as frequently as every day. Winter squash is ripe if your thumbnail doesn’t mark the skin and the stem is dry and brown. Cut the stem about 4cm (2”) from the fruit. Squash survive a light frost, but store better if harvested before frost.

Storage: Field-cure for 10 days in the sun, or cure indoors in a warm room for 4 or 5 days. To prevent mould sponge the skins with a solution of 10 parts water to 1 part chlorine bleach. Store at 10-15°C (50-60°F) with low humidity with good air circulation. Try on a shelf in the garage.

Seed info: In optimum conditions at least 80% of seeds will germinate. Optimum soil temperature for germination: 25°-35°C (68-95°F). Usual seed life: 2 years.

Growing for seed: All squash varieties will cross-pollinate within their species, but not between species. You can grow one variety of each of the three species side by side without any cross-pollination occurring. Isolate individual varieties within a species by 1km (½ mile) if you are planning to save the seeds for the purposes of planting again. Otherwise, plants can be hand pollinated, with the fertilized female flowers taped shut so they cannot receive any insect visitors.

Pests & Disease: Bacterial wilt (Erwinia tracheiphila) – Remove and destroy infested plants. If striped or spotted cucumber beetles appear control as soon as possible. Powdery mildew – avoid wetting foliage if possible. Water early in the day so that above ground parts will dry as quickly as possible. Avoid crowding plants and eliminate weeds around plants and garden area to improve air circulation. Viral disease – Remove and destroy entire infested plant along with immediately surrounding soil and soil clinging to roots. Eliminate wild cucumber and milkweed nearby. Control aphids early in the season by washing off with water as needed early in the day. A hard stream of water can be used to remove many aphids.

All squash plants bear their male (pollen producing) flowers at the ends of long, narrow stems like the ones shown above.

All squashes also bear female (pollen receiving) flowers. Note the thickened base of each – this is the ovary of the flower. If it is fully fertilized, it will swell into a mature, seed-bearing fruit. If you notice squash (particularly zucchini) fruit that wilt or yellow at the blossom end, it is a result of incomplete pollination. These should be cut from the plant and discarded or composted.