Growing Cape gooseberry

The cape gooseberry originally comes from the highlands of the South American Andes and belongs to the nightshade family. That makes it a close relative of tomatoes, peppers and potatoes. In its homeland it grows as a perennial shrub, but here it's usually grown as an annual because it can't handle frost. If you fancy, you can dig it up before the first frost and overwinter it in a frost-free spot.

The botanical name Physalis comes from the Greek word for 'bladder' and describes the papery husk that wraps around each fruit like a little lantern. This husk isn't just pretty to look at – it naturally protects the berry from pests and weather. The flavour of ripe fruit is uniquely sweet-tart, somewhere between gooseberry, kiwi and a hint of pineapple.

The plant arrived in Europe at the end of the 18th century, initially as an ornamental. Via South Africa, where it thrived so well at the Cape that it picked up the name 'Cape gooseberry', it found its way into our gardens. Home-grown fruit tastes noticeably more flavourful than the often unripe supermarket offerings.

All green plant parts and unripe fruit are mildly toxic and can cause nausea and stomach cramps.

The cape gooseberry needs a long growing season, so starting it indoors is essential. Direct sowing outdoors doesn't work in our climate. From mid-February to mid-March, sow the seeds about 0.5 cm deep in low-nutrient seed compost. At temperatures of 20 to 25 °C they germinate in 7 to 21 days, though the timing varies depending on variety and conditions. If you don't have a grow light, it's best not to start before mid-February, otherwise the seedlings get leggy and thin.

After about three to four weeks, prick the seedlings out into larger pots. They grow slowly at first, so don't worry if things seem to take a while. You can only plant them outdoors after the last frosts in mid-May. Before that, it's worth putting them outside in a sheltered spot during the day to harden them off gradually.

When planting out, leave 80 cm spacing in all directions – cape gooseberries get properly bushy. You can plant them a bit deeper than they sat in the pot; the buried stem will produce extra roots. If you want to keep the plant going for multiple years, dig it up in October before the frost and overwinter it in a bright spot at 10 to 15 °C. Cut the stems back by half beforehand. The following year, an overwintered plant fruits noticeably earlier and more abundantly.

The cape gooseberry loves sun – and lots of it. At least six to eight hours of direct sunlight a day keeps the fruit sweet and flavourful. A sheltered spot, for instance against a wall or hedge, is ideal because the stems are quite brittle.

When it comes to soil, the cape gooseberry is surprisingly easy-going. It should be loose and well-drained – sandy soils often give the best results. Waterlogging is the one thing it can't stand. A slightly acidic soil suits it best. Freshly manured ground is actually counterproductive: too many nutrients push leafy growth but slow down fruit production.

The cape gooseberry also works well on a balcony or patio. The container should hold at least 15 to 20 litres, ideally 30 to 40 litres. A drainage layer at the bottom of the pot is a must to stop water sitting around.

There's a lovely range of varieties to choose from these days. 'Schönbrunner Gold' is the classic choice in German-speaking countries: open-pollinated, large-fruited and particularly aromatic, with a flavour reminiscent of kiwi and gooseberry. The plants can grow up to two metres tall and need plenty of space. For smaller gardens or balconies, 'Little Lanterns' is well worth a look – a compact variety with a trailing habit that works brilliantly in containers and hanging baskets.

If you're gardening in cooler regions with shorter summers, go for early-ripening varieties like 'Preciosa'. This one stays fairly compact at around 80 cm tall and delivers golden-yellow fruit from mid-August onwards. In warmer, more sheltered spots, you can happily choose the more aromatic but later-ripening 'Schönbrunner Gold'.

The cape gooseberry is fairly low-maintenance if you follow a few basic rules. Water regularly and evenly, especially during flowering and fruiting. Water at the base rather than over the leaves to keep fungal problems at bay. On hot summer days in full sun, daily watering may be needed.

A layer of mulch around the plants keeps moisture in the soil and regulates temperature. When it comes to feeding: less is more. Physalis is a moderate feeder – a decent helping of compost at planting time is often enough. Too much fertiliser gives you lush foliage but fewer fruit. For container plants, you can give a little organic liquid feed in July.

Staking the cape gooseberry is often a good idea, as the stems snap easily – especially when loaded with fruit or when it's windy. Put bamboo canes or a trellis in place early on. Pinching out side shoots isn't strictly necessary, but you can remove overcrowded or low-growing stems to improve air circulation.

The Cape gooseberry is a tough plant and usually stays healthy in the home garden. Its papery husk protects the fruit, and many tomato diseases barely bother it. It fends off late blight, for example.

The main troublemakers are aphids and whitefly, especially under glass and in warm summers. Both suck sap from the leaves, their sticky honeydew turns black, and aphids spread viruses. Ladybirds, hoverflies and lacewings help against aphids, and if there are only a few, you can simply hose them off with water. For whitefly, hang up yellow sticky traps and plant French marigolds between your plants right from the start. In the greenhouse, parasitic wasps do a good job.

In some spots, Cape gooseberries show signs of virus from July onwards, with mottled, mosaic-like and distorted leaves. There is no cure. Pull out affected plants and keep aphids and thrips in check, as they carry viruses such as tomato spotted wilt virus.

Overripe fruit often splits and then goes mouldy, which is grey mould. So pick regularly and give your plants enough space. In dry, warm weather, powdery mildew with a white coating can appear towards the end of the season. A newcomer in our gardens is white smut, a fungus that causes yellowish-green leaf spots and a white layer of spores on the underside of the leaves. Pick off affected leaves and put them in the general waste, and only save seed from healthy plants.