A Guide to Growing Summer Squash, Zucchini and Marrows

Learn how to make these delicious summer vegetables a vibrant part of your garden with this planting guide.

Train Squash to Grow on Supports or in Cages

Train Squash to Grow on Supports or in Cages

Train summer squash to climb a trellis or cage for support as the plant produces more and heavier fruits during growing season.

©2011, Dorling Kindersley Limited

2011, Dorling Kindersley Limited

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Summer squash are a lot like zucchini in terms of growing, cooking and eating, but they come in a much wider variety of shapes and textures. They are attractive plants and fun to grow. Zucchini and marrows are also very similar with their major difference being their size. When harvested small, zucchini has a delicate flavor and tender skin; marrows, on the other hand, develop a thicker skin over time. 

How to Grow Summer Squash

These vegetables prefer moist, rich soil and crop better in hot summers. Sow seed under cover in early spring into small pots, harden off, and plant outside into large containers or beds when all risk of frost has passed. Plant bushy varieties 18 inches apart and trailing types 3–4 feet apart. Seed can also be sown outside under cloches at this time, 1 inch deep. Water well, and when squash appear, feed with a high-potash fertilizer every week. Tie trailing varieties to supports, and pinch the tips when they are 24 inches tall. Harvest squash while small for best flavor, cutting their stems at the base with a sharp knife. Wear gloves — older stems may have needle-sharp bristles. 

Types and Varieties of Summer Squash

Patty pan squash have a flattened shape with a bumpy ring. The plants can double as garden ornamentals when trained against fences Varieties of patty pan squash include ‘Custard White’, ‘Moonbeam’ F1, ‘Peter Pan’,  ‘Scallop Yellow Bird’ and ‘Sunburst’ F1. Round squash can also be highly decorative, producing fruits with colorful patterned skins that can be smooth or knobby in texture. Varieties to try include  ‘Festival’ and ‘Summer Ball’ squash.

How to Grow Zucchini and Marrows

These plants can be grown in beds or large containers and need a warm, sunny spot with fertile soil. Sow seed under cover in early spring, or outdoors under a cloche, 1-inch deep when the risk of frost has passed. Plant bushy varieties 24 inches apart and trailing types, which can be trained up canes, 3–4 feet apart. Water well, and feed with a liquid fertilizer every week. Using a knife to cut their stems, harvest zucchini at 4 inches long, or for marrows, thin the fruit to two or three per plant, and allow them to grow to 8–12 inches. Pick zucchini when it is young and tender, but leave marrows to develop a thick outer skin.

Varieties of Zucchini and Marrows

Most zucchini are green, but some are yellow (Y), which makes them easier to see when harvesting, including ‘Clarion’ F1, ‘Defender’ F1, ‘Gold Rush’ F1 (Y), ‘Jemmer’ F1 (Y), ‘Romanesco’, ‘Supremo’ F1 and ‘Venus’ F1. Marrows are large zucchini, but there are also varieties available that are particularly suited to growing as marrows, including ‘Badger Cross’ F1, ‘Clarita’ F1 and ‘Tiger Cross’ F1.

Watch Out for Diseases and Pests

Squash, cucumbers, zucchini and pumpkins are related and are affected  by the same pests and diseases. The cucumber mosaic virus affects squash as well as cucumbers, causing the foliage to become yellow and mottled, weakening the plants and reducing the crop. There is no cure for this disease, so plants must be destroyed.

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