Pumpkin

Light and exposure

The pumpkin wants full sun and warmth. Give it the most exposed spot in the vegetable garden, six hours of sun a day at the very least, otherwise the fruits struggle to swell and ripen before autumn.

Above all, plan for space, plenty of space. The vines run over several metres and smother everything they meet. Allow two to three square metres per plant, or train the small varieties up a trellis to save room, supporting each fruit in a net.

Watering

The pumpkin drinks a great deal in summer. Its large leaves transpire heavily and a plant short of water abruptly stops setting fruit. Water generously at the base, two to three times a week in dry weather, more during a full heatwave.

Always water at ground level, never over the foliage. Wet leaves in the evening invite powdery mildew, which settles in quickly here in late summer. A good mulch at the base keeps the soil cool and spaces out the watering.

Soil and repotting

The pumpkin is a hungry plant that demands a very rich, deep soil. Add a large amount of well-rotted compost or decomposed manure at planting, one or two buckets per plant. The classic trick here is to plant it straight on the compost heap: it finds everything it loves there.

Planting is done from a pot, a single well-rooted plant per spot. Dig a wide hole, mix the soil with compost, and leave two to three metres between plants. From a pot, only transplant after mid-May, once the mild nights have set in.

Temperature and humidity

This is the critical point in Belgium. The pumpkin grows well between 18 and 30 degrees and tolerates no frost. A simple cold snap below 10 degrees halts growth, a frost burns the plant in a single night.

Do not be fooled by a mild April. Late frosts still strike right up to mid-May, the period of the ice saints. Sow warm indoors, at 20 degrees, and wait until those days have passed before moving anything out. At the other end of the season, beware the first autumn frosts, which often return as early as late September.

Pruning and upkeep

Pruning is not compulsory but it helps produce fine fruits ripe in time under our short-season climate. When two or three pumpkins are well formed on a plant, pinch off the tips of the stems so that the plant feeds the fruits in place rather than running on endlessly.

Slip a board, a tile or a bed of straw under each swelling fruit. Left on damp soil, a pumpkin quickly rots from underneath. Straw insulates it from the ground and keeps it clean and healthy right up to harvest.

Pests and diseases

Powdery mildew is the great enemy here, almost unavoidable in late summer. You recognise it by a white powdery felt on the upper side of the leaves. It arrives late, often after the fruits have set, and then does little harm: the harvest is already under way. Give the plants air and water at the base to delay it.

Watch out too for fruit rot, encouraged by contact with waterlogged soil, which is why straw underneath matters. Slugs attack young plants in spring and can strip a sowing in a single night: protect the freshly moved-out pots.

Propagation

Sowing is the only common route. Sow warm indoors in April, at 20 degrees, one or two seeds per pot, laid on their edge to stop them rotting. Emergence is fast, less than a week at the right temperature.

Save your own seed in autumn from a fine, fully ripe fruit: rinse it, dry it and keep it dry. Beware, squashes cross easily between varieties, a saved seed can give a fruit very different from the parent, sometimes bitter. For reliability, start again from bought seed.

Toxicity

Not toxic, the flesh and the seeds can be eaten without concern. One rare caveat: some squashes turn bitter because of cucurbitacin, a substance that causes digestive upset. Never eat a squash with a distinctly bitter taste, spit it out and throw the fruit away.

Month-by-month care calendar

Green Hub tips

• Plant the pumpkin straight on the compost heap: it loves rich soils and you save yourself a separate feed.
• Never move the plants out before mid-May. A mild April is a trap, a single late frost kills the plant.
• Slip a board or a bed of straw under each swelling fruit, otherwise it rots on contact with the damp soil.
• Harvest when the stalk is dry and corky, cure in the sun, then bring in somewhere cool and dry: the pumpkin lasts all winter.