This sweet, sweet cucumber

I could really do with a drumroll effect and a ta-da sound here. After three years of trying, I have a crop of these large, heavy, purple-striped melon pears, which go by the botanical name of Solanum muricatum.

Actually I dislike calling them melon pears. As you can see from the botanical name, they are neither melons nor pears, and they taste nothing like pears at all.

I first encountered them on a trip to South America: they are a fruit commonly found in shops and on cafe menus in Chile. There they go under the name pepinos dulces, or sweet cucumber (and no, they're not actually cucumbers either).

The green fruit, which are the size of a teardrop-shaped grapefruit, are ripe when they develop the purple striping and there is a little - but not much - give when you squeeze them. Inside is all flesh with a thin fibrous core.

The taste is generally referred to as a meeting between melon and cucumber, hence the popular monickers for them. This means they are equally happy in a vegetable salad - a simple dressing of white wine vinegar and olive oil, salt and pepper, brings out the sweetness beautifully - or a fruit salad. Substitute for melon and it goes brilliantly with ginger and/or cured meats.

The seeds germinate easily enough, but previously I tried to grow them either outside, and then when that didn't work, in a soft plastic patio greenhouse. This year, I've had my first season with a 'proper' greenhouse and it has made all the difference as far as the sweet cucumber is concerned. They need a long season in the UK: sow in February in a heated propagator, and, if your greenhouse is unheated, keep them indoors until the nights are no longer chilly, so around May, then transfer to a sunny greenhouse and water regularly.

The plants are inclined to trail once they are established, and my greenhouse really doesn't have room for trailing plants so I trained them roughly up bamboo canes.

Around June/July, the plants should bloom with striking purple and white striped flowers. This is when you can really see that it is a Solanum: a pointed yellow pistil like a furled umbrella and petals folding back from the centre.

The emerging fruit looks like a small green plum to start with, then a pale green aubergine. The distinctive purple markings don't develop until it ripens, which should be by September or October. As I write this in mid-October, I can see two more small fruit developing on the plant, about the size of a hen's egg, but I strongly doubt there is enough time now for these to mature and ripen in the UK, even in the greenhouse.

Untried, untested - this year's new veg

I have my favourites in the kitchen garden, the crops I can’t imagine being without. I can’t imagine tiring of first early Lady Christl potatoes, or the candy-striped Chioggia beetroot, sugar snap peas, cavolo nero or Berrettina Piacentina squash or Sungold and Black Russian tomatoes.

But in other areas I am a lot more fickle. Quite deliberately I look for new veg and new varieties to try each year. It’s part of why I took on the allotment and the luxury of space for experimentation. Last year, I successfully grew ginger (indoors), physalis and sweet onions for the first time and was correspondingly unsuccessful with celeriac; the year before I had a complete 'mare with salsify.

This year’s newbies show a bias towards the new world. It’s partly intentional as I’m developing a Secret Garden Club workshop based on the food from the Americas, so some of the new produce is being grown for harvesting and tasting for the meet-up on September 1st (more info and ticket details here).

Mouse melon, or cucamelon (Melothria scabra)

These very attractive fruits look like stripey grapes and taste, apparently, of cucumber dipped in lime juice. We’re going to grow these in the Secret Garden this year – according to the supplier Suttons Seeds, the plants will climb vigorously, so we’re going to train these up a wigwam made of willow canes and hopefully we’ll be harvesting the fruit from July.

Melon pear

Or Solanum muricantum to avoid potential confusion. I first encountered these fruits which both look and taste like a cross between a  melon and a cucumber about 20 years ago in Chile, where they are called pepinos dulces. I’ve often wished I’d brought some seeds home as the climate in southern Chile isn’t so very different from the climate in northern London, and have been keeping a look out for them ever since. This year I found them in Thompson and Morgan’s catalogue. This is another one to grow indoors, cautiously, to start with and to see if the conditions warrant taking them outside into a sunny sheltered spot – my patio, in this instance.

Sweet potatoes

Although really a sub-tropical plant, cultivars of sweet potatoes (Ipomoea batatas , so related to the morning glory) are being bred to better withstand our cool wet summers. This year I’ve ordered some plug plants of the variety Beauregard to grow in a sheltered spot in the Secret Garden – the supplier, Suttons, claims that this is a better option than the more conventional sweet potato ‘slips’, or cuttings. They’ll need as much warmth as possible, so I’ll cover the ground the black plastic and plant them out through holes cut into it in late spring and cover with a Victorian-style bell cloche. Then we’ll see how the summer goes from there. If it’s anything like last year they’ll stay under cover. And even if they don’t provide much in the way of edible tubers, the young leaves and shoots are apparently also edible and can be cooked like spinach.

Tomato Black Cherry

There are so many tomatoes to choose from that it’s worth trying some new varieties every so often. I’m in a bit of a rut with tomatoes at the moment: Red Alert for early ripening, Brandywine and Marmande for cooking and making passata, Black Russian for flavour; Sungold for eating straight from the plant … Black Cherry looks as it would make a fabulously striking addition to a mixed salad bowl, like a Goth version of Gardener’s Delight. Available from Heirloom Tomatoes and others.

Pak choi Rubi

I can grow great pak choi under cover right at the start of the season, sowing in February or March to harvest in April and May, when, let’s face it, you’re not harvesting much else. After that, I find the slugs and the flea beetles get them, however much I try to prevent it, and also by May/June, lots of other summer vegetables are demanding attention. So pak choi is an early spring crop for me, and the more of it I can raise in that short space of time, the better. With this red version from Nicky's Nursery, I’m looking for a deeper, mustier flavour than the bright spring green of the conventional variety.

After our fantastic results with tomatillos in the Secret Garden last year, I’m going to try these on my rather more exposed allotment, where I’m also going to grow a couple of Szechuan pepper plants this year – more on this they're ready to go out into the ground. We’re also hoping to plant some witloof chicory for forcing in the Secret Garden later this year and I’ll blog more about that on the Secret Garden Club website once we’ve got going with that.