Kiwi Gardener

Pepino planning

in the south, Diana Noonan shares wisdom from the fruits of her labour on how to grow this juicy, melon-flavoured crop.

I’ve spoken briefly before about pepino, but now I want to talk about this fruit in more detail, to encourage any under-cover growers (especially those who live in cooler climes) who crave the delicate flavour of melons, to seriously consider planting this little-known food-bearing bush. Why am I so keen to crack on about pepino? It’s because I have some new insights into growing it. And if the comments of those who, this year, sampled my 60 or so pepino melons (the harvest of just four bushes) are anything to go by, it’s time cool-climate Kiwis knew how to grow this delicious fruit that is seldom, if ever, found in supermarke­ts.

hailed as one of the ‘lost crops of the Incas’, pepino are thought to be native to Colombia, peru and Chile. but the interestin­g thing is, although a close relative (Solanum caripense) exists in the wild, the pepino (S. muricatum) itself doesn’t, so it’s exact origin remains a mystery. Pepino are in the Solanaceae family (think tomatoes, aubergines and capsicums). They are indetermin­ate; in other words, they don’t grow as a vine, but scramble about all over the place. They are also frost-tender, so we often grow them during all seasons in our greenhouse, and therein (I believe) lies one of the problems. Let me explain.

pondering pollinatio­n

We know that pepino thrive in temperatur­es of 15–18°C, and that they won’t set fruit until night temperatur­es are above 18°C. But if temperatur­es are above 30°C, the flowers are very likely to abort. and thanks to some helpful new Zealand research, we also know that pepino are self-pollinatin­g (pollen from a flower pollinates the same flower) and cross-pollinatin­g (pollen from a flower pollinates a flower on the same plant). And that they are also capable of facultativ­e parthenoca­rpy (this is when a plant produces seedless fruit even though its flowers haven’t been pollinated). This ability

to set fruit in several ways should bode well for a harvest, but in my experience as a cool-climate greenhouse grower, it isn’t always that simple.

For the first years I grew pepino, I started the frost-tender plants from cuttings taken at the end of autumn, and wintered them over in the tunnel house (I still do). But I then kept the plants in the greenhouse (caged) throughout the growing season. In doing so, I reaped only three to four fruit per plant despite there being numerous flowers.

In my then ignorance, I put the lack of fruit down to a lack of pollinator­s, but as we now know, insect pollinator­s aren’t required for the fruit to set. so, either the temperatur­es in the greenhouse weren’t conducive to pollinatin­g (of any kind) or there wasn’t enough air movement to encourage self- or cross-pollinatio­n.

And perhaps facultativ­e parthenoca­rpy occurs only occasional­ly. If a lack of air movement was the problem, was it because the bushes, with their dense foliage, were caged, or was it simply because of a lack of airflow in the tunnel house? (Although, there was certainly enough to keep my other tunnel house plants happy.)

Here’s a possible answer. Because I was still assuming that the pepino flowers required insect pollinatio­n, i grew them in bags in the greenhouse until frosts were well and truly over, and then moved them outdoors into prepared ground in a sunny spot against a north-facing side of the house where i hoped the bees would have freer access to the flowers. And suddenly – wham! – the plants were covered in pepino melons. this has been the case for three years now. I’m no botanist, but i think that in the greenhouse situation, it was either a lack of sufficient airflow to move the pollen about within the individual bushes, or the outdoor environmen­t provided temperatur­es that were more conducive to fruit setting. whatever the reason, the problem has now been solved.

some like it hot

in a good, warm summer and autumn, these lovely melons turn a stripy purple and golden-yellow – helped by my picking off some foliage here and there to allow

the sun to reach them. This year, unfortunat­ely, the Catlins, which has a microclima­te all of its own, skipped spring, summer and autumn, and entered an early winter in May. So the fruit had to be picked green and brought inside to ripen as best it could. this rendered the pepino somewhere between a ripe cucumber, which is how they are eaten in many parts of South America, and a bland (but still delicious) melon.

plotting on

This coming growing season, I have a new plan up my sleeve.

I’m going to do my usual starting-off of the plants in bags (but larger ones) inside the greenhouse. Then, once the world warms up and frost danger has passed, I’ll move them outside to their sunny summer position, but I won’t plant them in their normally well-prepared fertile ground. Instead, I’ll leave the plants in their bags and feed them with liquid fertiliser. Hopefully, the fruit will ripen in situ. But if we don’t get a decent summer and autumn, I’ll bring the plants back inside the tunnel house to finish of the fruit ripening indoors.

Does it all sound worthwhile? Well, if you live in the south of the south, it’s amazing the lengths a keen greenhouse grower will go to in order to get variety into their harvest. And speaking from my own experience, pepino are worth every bit of the work it takes to get the goods. I hope you’ll give pepino a go in your own greenhouse this year. If you decide to, be sure to let your garden centre know ahead of time that you want to order in a couple of plants to experiment with.

Good luck!