How to Grow Squash

Botanical Name: Cucurbita pepo

Plant Type: Tender Annual

Summer squash are prolific and an easy vegetable to grow. Related to zucchini, these sprawling vines can be readily trained up a trellis. They are in the same family as pumpkins and melons, so you know they will taste good. Try them baked, roasted, steamed, and sliced and thrown into stir fries.

Varieties

Summer squash includes marrow, zucchini, patty pans, spaghetti squash and loofah. In Australia, we refer to each by its own common name rather than the group, however, all are grown in the same way.

Squash ‘Gem’ is a space-saving squash with grapefruit-sized fruit and ‘Jaune Et Verte’ is picked young and is sweet and buttery. Some varieties, such as Early Summer Yellow Crookneck, have quite a spectacular appearance, being covered in warts and blisters. Do not be put off by the unusual appearance or thick skin, they are popular for a reason – primarily their exceptional flavour and sweetness; they also remain a harvestable size longer than most sausage types.  

Spaghetti squash has grown in popularity in recent years, due to its ability to replace traditional pasta in myriad recipes. Patty pan squash are one of the fastest to reach maturity, providing ample produce, early in the growing season.

Cultivation

Easy to grow and incredibly productive, a few squash plants will go a long way.

Plant as you would pumpkins, in a soil enriched with compost and decomposed manure. Squash can be grown in flat beds, or preferably in mounds to improve drainage to reduce the likelihood of ‘Dampening Off’. Thin as required when seedling establish and begin to produce their vines. If training up a trellis, allow the vines to grow around 1m before tying to a trellis or frame. This will help to maximize your harvest in a small amount of space. It can also make it easier to spot fruit and pick at the right time, avoiding those sneaky marrows.

Sun: Full Sun           

Pollination: Insect pollinated

Soil: Enrich soil prior to planting with decomposed manure and well-rotted compost. This will improve the nutrients, organic matter and water holding capacity of your soil. An application of rock dust prior to planting will also help to reintroduce many trace elements missing from modern soils. 

Growing from Seed

Sow: Direct sow after frost or sow in punnets.

Ease of Germination: Easy

Germination Temperature: 21°C–35°C

Germination Time: 7-10 days

Spacing: 80cm

Harvest: 60-90 days

Yield: 6-24 fruit per plant

Sow more seed than required to ensure successful germination, but thin as the vines begin to develop to avoid overcrowding. There is usually no need to stagger your planting as plants produce such a prolific harvest within the season, especially when picked regularly.

If growing in punnets, transplant carefully after all likelihood of frost has passed. Plants will establish quickly and can be trained to a trellis or grown in pots where space is limited.

Maintenance and Additional Care

Water regularly but avoid wetting the foliage to reduce the likelihood of powdery mildew. Monthly applications of a seaweed and fish emulsion like Ocean Brew will help to keep plants healthy.

Companion Planting

Good companions: Borage, Capsicum, Chilli, Chives, Corn, Lettuce, Nasturtium, Peas, Radish, Spinach, Tansy, Tomato

Bad companions: Potato

Pests and Diseases

Members of Cucurbitaceae, squash are susceptible to a range of fungal diseases, especially as they mature. These include powdery mildew and downy mildew.

Downy mildew typically produces light-gold angular spots (which in the later stages are covered by a fine white powder that turns brown) on the leaves and purple spots on the undersides. Warm, humid weather, particularly extended periods of summer rain, favour outbreaks of downy mildew. Powdery mildew is readily identified by the presence of fuzzy white patches on top of the leaves, eventually spreading to kill whole leaves. Outbreaks are encouraged by warm days followed by nights of heavy dew. Rain generally inhibits outbreak of powdery mildew.

In our experience, these two diseases tend to be a problem only in the latter part of the season, and being largely environmental, are difficult to control.

Blossom end rot can also occur and, like tomatoes, is caused by calcium deficiencies in the soil, waterlogging of the soil, or irregular watering.

Container Growing

Squash can be grown in pots, where their vine can either trail over the side or be trained to a trellis. Always use a premium potting mix that meets the Australian Standards (look for the tick on the bag). When grown in pots, plants will need more frequent watering, but hopefully, you’ll be able to spot those yummy fruits more easily when they are ready to harvest.

Harvesting

Pick frequently as crops start to bear fruit. Patty pan squash should be picked daily to maximize yield and reduce the number of fruits which become too large. Spaghetti squash can be harvested when yellow.

Seed Saving

Seed Longevity: 4-6 years

Isolation Distance: 400m

How to Save Seed: To save seed, allow fruit to remain on the vine until the skin become thick, like a pumpkin. Once harvested, leave to mature for 4-6 weeks before scooping the seeds from the pulp. Wash to separate the seed and pulp and dry the seed on paper towel. As with pumpkins, viable seed will sink, while non-viable seed will float. Save only viable seed for sowing next year. Once dry, seed can be store in an envelope in a dark, dry environment.

Tips and Tricks for Success

• in cool climates, start seed in punnets ready for transplanting after the first frost. This will speed up your time to first harvest.
• inadequate pollination of flowers will cause the small, developing squash to shrivel and drop from the plant. Squash produces separate male and female flowers, and pollen must be transferred for pollination, and fruit set, to take place. Bees will pollinate your squash flowers, or you can move the pollen from the male flowers to the female with a small paint brush.