Cucurbita pepo
Zucchini and its relatives are the crop that teaches beginners they can grow food: two plants will keep a household in fruit all summer. The skill is not growing it but picking it small and often, and staying ahead of the borers and mildew.
Pollinated by insects — fruit sets only where bees and other pollinators reach the flowers. Needs insects to move pollen from the male flowers to the female ones, and each flower is open for a single morning. Cold cloudy or rainy weather keeps bees off and the result is small fruit that yellows and drops. Hand-pollinating mid-morning works when fruit keeps aborting.
As much sun as you can give it. Squash in shade makes big leaves and few fruit.
Water deeply once or twice a week at the base of the plant. Big leaves lose a lot of water and a dry spell makes the small fruit shrivel and drop.
Rich soil with plenty of compost. Squash is a hungry plant with a lot of leaf to build.
Dig compost in before planting and give one feed once the plant starts to spread.
Nothing to tie up. Take off the oldest lower leaves as the plant grows so air can move underneath, and hand-pollinate if fruit keeps shrivelling.
Pick at 150 to 200 mm, three to five days after the flower opens, and look every single day. A marrow left on the plant tells the plant to stop making more.
Up in under a week in warm soil. In cold soil the seed rots instead, so wait for warmth rather than the calendar.
The riskiest three weeks of the plant s life. Keep the seedlings covered and look at them every day.
The plant bulks up fast. Feed it once as it starts to spread, and start checking the stem base.
Male flowers come first, then females with a tiny fruit already behind the petals. Each flower is open for one morning only.
Fruit goes from flower to picking size in three to five days, so look every day.
Pick every day or two right up to frost, or until mildew closes the season down.
Zucchini or courgette
Straight cylindrical fruit picked at 150 to 200 mm, green or golden. The most productive and the most widely grown type, and mostly bush-habit rather than trailing.
Pattypan or scallop
Flattened round fruit with scalloped edges, picked at 100 to 150 mm across rather than by length. Firmer flesh than zucchini and it holds its shape better cooked.
Yellow crookneck
Yellow fruit with a curved narrow neck and a bulbous end, picked small at 100 to 150 mm. The skin toughens and goes bumpy earlier than zucchini so it is less forgiving if you miss a day.
Yellow straightneck
Yellow and straight rather than crooked, otherwise handled exactly like zucchini. Easier to pack and less prone to snapping at the neck than crookneck.
Stages affected: Vegetative · Flowering · Fruiting
The caterpillar of a day-flying moth that tunnels inside the base of a squash stem. It is the commonest reason a healthy squash plant collapses overnight in midsummer, and by the time the plant wilts the grub has been inside for weeks.
Stages affected: Seedling · Vegetative · Flowering · Fruiting
A flat grey-brown shield-shaped bug that sucks sap from squash leaves and stems. Small numbers do little harm but they breed through the season, and a heavy population wilts and kills whole vines. The egg clusters are the easiest thing to find and the best thing to destroy.
Stages affected: Flowering · Fruiting · Harvest window
White powdery growth on squash cucumber and melon leaves, arriving in mid to late summer and spreading fast once it starts. It rarely kills the plant outright but it shortens the season: the leaves die back, the fruit stops sizing and the fruit still on the plant sunburns once the canopy thins.
Stages affected: Germination · Seedling · At planting
A small yellow beetle with three black stripes that feeds on cucumber squash and melon. The chewing itself is survivable on an established plant, but the beetle carries the bacterium that causes bacterial wilt, and that is what actually kills the crop. On seedlings both the feeding and the infection risk are serious.
Stages affected: Fruiting · Harvest window
Not an infection but a disorder: a firm dark patch at the base of the fruit caused by calcium failing to reach the fruit as it grows, almost always because soil moisture swung between wet and dry. Tomato pepper aubergine and squash all get it.