Native to Peru and Chile in South America, it was apparently reported by the Spanish Conquistadors as being cultivated on the coast in the Moche Valley of Peru. It has been cultivated in the warmer parts of the USA for over a century, and more recently it is being cultivated commercially in New Zealand and Chile. However, as it is difficult to handle and does not travel well, it is rarely seen in the UK for sale, except at exorbitant prices. However, mixed seed, containing several different varieties, is now available in seed catalogues in the UK. For convenience, I have included the Pepino in this soft fruit section, though you may find the seed listed in the catalogues in the vegetable seed section as “tomato relatives”.
It is a perennial evergreen shrub growing to a metre outdoors or up to 2 metres in a greenhouse or conservatory. Unfortunately, it is extremely frost tender and will be cut back to ground level at -2 C. Therefore in the UK, it would be a suitable for a frost free Conservatory or heated greenhouse, with good light. The compost should be kept moist.
Growing from seed is surprisingly easy. Treat the seed just as you would with peppers or tomatoes. Sow the seed in pots of free-draining compost, just covering the seed, in late January or early February. Place in a propagator at 20-23 C until germination takes place (under 14 days), and then transfer to a light position at 18-20 C. The seedlings will grow slowly for the next 2 months, until they are ready to be repotted into their final pots or growbag in a cool or heated greenhouse or conservatory. The seed available in the UK produces very variable plants with different types of fruit, as shown in the photos.
Pruning and “pinching out” the growing tips, will be necessary to keep the plants under control in a greenhouse or conservatory. The main stem will require to be well tied and supported to a cord or cane as the stems are very lax. The growth habit is “indeterminate,” and pinching out any side shoots but leaving any flower buds, as you would do for a tomato plant, would be a good method of pruning and training the plant. This coming season, I will also be trying a slightly different system of pruning in which I shall pinch out each side shoot, two leaves beyond any fruit buds.
By sowing the seeds early, the plants should start to flower in early August, and continue till October. While the plants start to flower quite readily, it is a difficult to get the flowers to set fruit. Some sources suggest that a nighttime temperature minimum of 16 C is required to get a fruit set, rather difficult even in a greenhouse. The plants are self-fertile but require pollination by insects in the wild. In the Greenhouse, hand pollinate with your finger or a fine artist’s brush. High temperatures above 30 C, can also apparently prevent fruit forming.
The fruits grow very quickly at the beginning and have different sizes, claimed to be up to 15 cm long, though my seed only produced fruit up to 7 cm long. The fruit colours range from pale cream to green, and different shapes from egg-shaped to rounded, depending on the variety.
The fruit seem to be slow to ripen in our climate, but eventually, the pepino’s skin will turn a deep yellow or gold with purple stripes. The changing of the colour of the stems supporting the fruit, from green to cream, give a further indication that the fruit is ripe (see photo).The fruits will be firm with just a slight give when gently squeezed with the fingers. The juicy flesh inside is a orange-yellow colour and smells and tastes similar to a cantaloupe melon. The flesh is firmer and more finely grained than a melon. There are a few seeds inside which are edible. They should store for a week or two in a fridge
The fruit can be eaten raw if the skin is peeled first, and added to fruit salads. The brightly coloured skin and flesh, make an interesting contrast to other fruits.
Starting from seed, in my Glasgow cool greenhouse the fruits had not ripened by the time of the first frosts in October. When the plants were transferred to an indoor sunny windowsill, the fruits eventually ripened in December. Rather surprisingly, the plants continued to grow vigorously, producing numerous flower buds, even in the very poor daylight in December. In other words, the plants are not daylight sensitive.
By taking cuttings in December or January in heat, for the coming season, I shall make a flying start and see if it is possible to get a reasonable crop of fruit to ripen in the cool greenhouse. At least by mid-April, the cuttings are starting to flower but have still to set fruit, some 3 months before seed sown plants.
The Pepino roots readily from cuttings, even in midwinter in 4 to 5 days in water. These cuttings should be potted-up and them can be over-wintered in a frost-free place and planted out into growing positions the following year. This method is particularly used for commercial crops to combat pest and disease problems, as well as frost tenderness.
Pests and diseases. Assuming that you will be growing your Pepino plants indoors, watch out for greenfly, white fly and particularly red spider mite and spray accordingly. I saw no sign of blight when grown in the greenhouse, but in the wild, commercial crops have been decimated by other fungal diseases.
For feeding the Pepino plants, use a tomato liquid feed, high in potash, about once a week. Too rich a nitrogenous feed will only encourage leafy growth and we want fruit production.
There are some named cultivars but these are not likely to be readily available in the UK.
Growing Pepino plants outdoors should only be attempted in particularly mild, frost-free parts of the UK, due to it’s susceptibility to frost damage. Even then, you would be advised to cover the roots with a thick mulch, to protect them from frost damage. If the tops do get cut back with a frost, they will probably re-grow from the protected roots.