Growing and harvesting zucchini

Zucchini is one of the most productive vines of summer, producing a mass of edible flowers followed by fruit, which many mistakenly call a vegetable. The sprawling vine can be trained up a trellis or frame or allowed to spill out from their garden beds or pots.

What you need to know about zucchini

Name: zucchini, courgette, squash, marrow, summer squash, gourd (Cucubita pepo)

Height: sprawling vine to 3m

Foliage: annual with large green leaves.

Climate: zucchini is a summer crop in areas with hot dry summers, and a cool-climate crop in tropical and sub-tropical areas.

Soil: prefers deep, well-drained soil enriched with aged manure and compost.

Position: full sun with room to spread.

Flowering and fruiting: zucchini produces both male and female flowers. The male flowers appear on long thin stems, while the female flowers have shorter stems and produce the actual fruit from the base of this stem.

Feeding: a monthly application of blood and bone or dynamic lifter, and regular treatment with a seaweed-based solution during the fruiting season.  

Watering: regular watering is required to keep plants productive and healthy. Water daily during hot dry weather; less often if soil is mulched and the weather mild. Avoid wetting the foliage, as this can lead to fungal problems.

Two near ripe zucchinis

Appearance and characteristics of zucchini

Zucchini is an abundant sprawling vine with large green gritty leaves that have a texture similar to sandpaper, and hollow, crisp, hairy stems with small prickles that protect the developing fruit from accidental harvest by large pests (such as livestock). The fruit develops at the base of the female flowers, with both male and female flowers appearing throughout the fruiting season. Fruit develops quickly, with small zucchinis rapidly becoming large marrows if left too long on the vine.

How to plant and grow zucchini

Zucchini is easy to grow and relatively trouble-free.

Growing zucchini from seed

  1. Sow seeds when soil temperatures reach a minimum of 15°C.Sow seed to a depth of 2cm.

  2. Alternatively, sow in seed trays and transplant when all likelihood of frost has passed.

Planting zucchini seedlings

  1. Plant seedlings in a soil enriched with decomposed manure and compost.

  2. Apply a handful of blood and bone or dynamic lifter at planting.

  3. Position 2–3 plants together, in clumps at least 1m apart. This will help with pollination.

  4. Plant at the same height as the seedling was in the punnet.

  5. Mulch to conserve soil moisture and to protect the developing fruit. Protect seedlings from snails and slugs with snail and slug pellets or traps.

How to harvest zucchini

  1. Harvest zucchini using secateurs to avoid damaging the vine. The more you pick, the more fruit the vine will produce.

  2. For best flavour, pick the zucchini when young.

  3. If harvesting flowers, remember that this may be at the expense of the developing fruit.

Caring for zucchini

Water regularly in dry weather and during the development of flowers and fruit. Avoid overhead watering, which can increase the likelihood of fungal problems.

Apply a handful of blood and bone or dynamic lifter monthly during fruit development, and apply seaweed solution fortnightly to help prevent fungal infection and maintain plant vigour.

Diseases and pests

Snails and slugs will attack young seedlings. Protect your zucchini using snail and slug pellets or traps.

Fungal infections such as powdery mildew or downy mildew can become a problem during the growth cycle. If found, remove infected leaves and spray with one part milk to four parts water. To minimise the risk of infection, space plants at least 1m apart and avoid overhead watering.

How to propagate zucchini

Zucchini is propagated by seed collected from mature zucchinis.

  1. Allow a couple of fruits to become marrows (large with very thick, hard skin).

  2. Harvest and store for two weeks to allow the seeds to plump out before harvesting the seed.

  3. Break open and gather the seeds from the centre of the fruit, washing them to remove any flesh still clinging to the seeds.

  4. Spread the seeds out evenly over paper towel and allow to dry. When the seed is dry, it will snap when bent.

  5. Store in a clearly marked envelope in a dry location for sowing next spring.

If you like this then try

Tomato: plant at the same time as zucchini for a bumper harvest.

Capsicum: a summer favourite suited to stuffing and roasting.

Corn: grow your own corn and you can make zucchini and sweet corn fritters. 

Start planting today

Check out our huge range of plants now and get your garden growing!

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