Growing cucurbits – cucumber, zucchini and pumpkin
Plant in September in punnets, or from October to December outside. Choose a site with full sun and shelter from wind.
Plant cucurbits as seed or seedlings on mounds of compost with a base of well rotted animal manure. The manure should be spread as far as the stems will run as the runners of cucumber and pumpkin will attach to the soil and feed from it. Avoid nitrogen-based fertilisers (compost and well rotted animal manure are not nitrogenous, but fresh manure is). Add in some potash (available in packets from your nursery) or wood ash. Cover the mound with wire netting, until the plants are well established, to prevent birds scratching them out or small rodents eating the tender shoots. Planting seed 5cm deep protects it from rodents
Planting and spacing
Ideally raise seeds in punnets and transplant. This way you will know, that your seedlings have come up and not been eaten if seed was direct planted, and you will get a head start. Cucurbits germinate between 15 -24C. Below 15C they are slow to germinate and grow. If you plant seeds directly, plant 3 lots of 2 seeds per mound in a triangular formation and thin out weaker seedlings later if necessary (or transplant them). Mounds for cucumber and zucchini should be 40 cm apart and for pumpkins 80 cm apart. Rows for both should be 1 metre apart. Climbing cucumbers will need a frame.
Planting in pots
Only for cucumbers. Use a pot of at least 40 cm diameter and fill with a 50:50 mix of compost and potting mix.
Water at planting, then every second day until seedlings are well established. Then water deeply twice weekly. Water in the morning and onto the soil, not the leaves, to avoid powdery mildew developing. Keep soil moist at all times and mulch to keep the roots cool.
Add potash at flowering time for all 3 cucurbits. Add a monthly side dressing of compost or well-rotted manure.
Developing lateral growth
To develop lateral growth, pinch out the tips of cucumbers when they have 6 leaves, and pumpkin tips when they are 4 – 6cm long. This will result in more fruit, and also stop pumpkins running everywhere.
How to avoid blossom end rot in zucchini
This can occur in zucchini and as the name implies, causes rotting on the end of the fruit. Technically, it is a result of the plant getting an inadequate supply of calcium, but this is usually caused by the plant not getting sufficient water to its flowers and fruit. Strengthen the water delivery system by applying additional potash around each plant at time of flowering, and make sure you are giving the plant adequate water.
Diseases and Pests
There are many, but the most common are:
- Cucumber mosaic virus affects all cucurbits, turning leaves motley, distorting their fruit and making them bitter. It is transmitted by aphids. Keep area and surrounds weed-free as viruses are often transmitted by aphid from weeds.
- Powdery mildew is caused by water on the leaves especially late in the day. Spray with a solution of 9 parts water:1 part milk.
Certain beetles including cucumber beetle and stink bug can attack cucumber and zucchini. Slugs and snails can be a problem.
When to harvest
Cucumbers: when they are small and before they yellow.
Zucchini: when they are small.
Pumpkins: when the stem coming out of the top of the pumpkin has withered. Leave 10 – 12 cm of stem but don’t use it as a handle. Cure pumpkins for 4-8 weeks which hardens the skin and develops their sweetness. Lay on mesh or wire with straw or newspaper on top. This allows air circulation. Keep in a sunny spot and keep dry. Half way through the curing period turn pumpkins but be careful not to damage the stalk.
Written by Robin Gale-Baker