At a glance
Ease of culture: Easy
Where: All except very cold climate
Best climate: Warm conditions
When: Spring, summer, autumn in cool areas, winter in warm to hot areas
Spacing: Cucumber 20-30cm; zucchini 1m; pumpkin 2m
Harvest: Cucumber 8-10 weeks; zucchini 6-8 weeks; pumpkin 15-20 weeks
• Cucurbits require warm, frost-free conditions
• In cool areas, start seedlings early in pots by a sunny window or protected by a mini-glasshouse and plant in spring when the soil warms.
• Cucurbits can grow for much of the year in the tropics, but perform best in the dry season (April – September) – cucurbits are highly susceptible to fungal disease and rotting in the wet.
• Spring and autumn are best for zucchini and cucumber in the subtropics, but watermelons and pumpkins will continue to thrive throughout the summer.
• All cucurbits prefer full sun
• Their foliage is easily damaged and dried out in wind – particularly zucchini and squash – so find a protected spot where possible
• Cucurbits demand a rich, open organic soil with excellent drainage.
• Enrich the soil before planting with generous amounts of compost or well-rotted manure
• Create a planting mound for each plant to further improve drainage
• In temperate and subtropical areas, sow and plant cucurbits seedlings from September to January. In cooler areas, start plants in pots in September and grow them under glass until the soil is warm enough for planting in October/November.
• Seedlings are readily available in garden centres during the planting season, but cucurbits are very easy to sow from seed directly in the soil.
• Sowing your own seed allows you to try some of the more unusual heirloom varieties not normally available as seedlings.
• Plant 2-3 seeds in each planting mound 10cm apart, and then thin them out to leave only the strongest seedling.
• Water seeds in well, but don’t water them again until they germinate – they are very prone to rotting.
• Don’t overcrowd cucurbits. They are very prone to fungal disease and need good airflow around the vines. In general, allow 2m between pumpkin and watermelon vines, 1m between zucchinis and squash and 20-30cm between cucumbers
Watering and fertilising
• Cucurbits are vigorous growers. To maintain healthy growth, give plants a light application of an all-purpose organic fertiliser in the first week after germination and follow up with regular light applications every 3-4 weeks.
• They have lots of foliage and dry out easily, so keep soil at the base of plants evenly moist once they’re up and running. Irregular watering can lead to poor production and poor-quality fruit.
• Keep water off foliage and fruit where possible to reduce fungal disease.
• All cucurbit vines will climb if you let them.
• This is the best way to grow cucumbers. Install a 1-2m-high trellis at planting to support vines and fruit. This saves space and keeps fruit off the ground.
• Pumpkins and melons can be trained over a sunny shed or pergola to save space in small gardens
Box: Overcoming poor fruit set
Poor fruit set in cucurbits is often due to inadequate pollination and lack of bees. Pollinating flowers by hand will guarantee a sizeable crop and is easy to do. Identify the male and female flowers. Males have long slender stems and female flowers have a swollen base, like an immature fruit. Pick off a male flower, remove the petals to reveal the central 'style" and brush the pollen onto the pistil inside the female flower. The best time to do this is early morning. Check plants daily.
Use secateurs to remove cucurbits from their vines to avoid damage to fruit and vines. Leave a length of stem on the fruit to keep disease organisms that can rot fruit from entering fruit postharvest.
Pumpkin – Harvest when stems are hard and dry. Clean and dry fruit and store in a cool, airy and dry spot.
Watermelon – Picking a ripe watermelon from the garden is one of life’s greatest pleasures. Give the fruit a tap – a ripe melon will have a dull thud sound. Also check the skin of the fruit where it meets the ground. It should be a yellow-white colour when mature.
Rockmelon – Smell the fruit. Ripe rockmelons have a strong sweet smell and come away freely from the vine. Store in the fridge.
Zucchini and squash – Harvest young (zucchini 15-20cm long, squash 7-15cm wide) and store excess in the fridge. Bigger fruit become watery and lose flavour. Check and harvest plants every 1-2 days.
Cucumber – Depends on variety and use. Small fruit less than 10cm long are best for pickling. Harvest young to avoid large seeds.