Pumpkins & Squashes
The RHS share their expert tips for getting amazing results from pumpkin and squash plants, every time
RHS GROWING GUIDE
Pumpkins and squashes are a succulent and nourishing autumn and winter vegetable adding body and sweetness to soups, stews, roasts and pies. They are pretty much the same botanically and horticulturally speaking, and they have identical growing requirements, too. Originating from North America and deriving from a hodgepodge of five species, these have given rise to the hundreds of different cultivars that are grown today.
All pumpkins and squashes are frost sensitive. Seed is started indoors from April or direct sown seed outdoors from mid-May to early June. If indoors, use a well-drained peat-free potting compost, and ideally germinate seeds in a heated propagator to aid success.
Plant them out when all risk of frost has passed. They need full sun and a free draining and very fertile soil. The old trick of planting in compost heaps is a good one. These hungry crops appreciate some balanced granular fertiliser such as ‘fish, blood and bone’ before planting. They need plenty of space – 2m (6ft) between rows and 1m (3ft) between plants. Water them well in dry spells.
From mid-summer, flowers start to appear with separate male and female flowers. The latter have small, undeveloped swelling behind the petals that will produce the fruit. Flowers held on long, thin stems are male and both are needed for successful pollination. Happily they cross-pollinate readily with the help of bees and other insects.
Once fruits start forming, regular watering will swell the fruits – especially in dry summers. Potassium-rich liquid fertiliser such as tomato feed, every week will boost fruit size, but this is not essential for smaller fruited cultivars. Trailing forms roam widely. They can be curled to limit their spread or, especially smaller fruited forms, can be trailed over tepees or other structures. Stems can be pruned once a fruit has formed allowing two leaves to feed the fruit, but this eliminates the chance of further fruits being formed. Smaller fruited squashes, such as butternuts, produce several fruits per plant but larger fruited ones may just produce single fruit.
By late summer, powdery mildew can become a problem. Regular watering and avoiding splashing moisture on the leaves helps prevent mildew, and cutting off and removing very infected leaves slows its spread. Weekly foliar sprays of liquid seawee
