A couple of years ago I sowed some seeds from an outdoor passion flower fruit that I acquired from a friend and got a batch of seedlings, four of which I have kept and one has flowered decently this year.

Spurred on by my success, I have now tried sowing seeds taken from a supermarket passion fruit and they have come up too. The problem is, how should I look after them, as I don’t think that they are hardy – or are they?

S COOK

Reg says: No, I’m afraid that, even allowing for last month’s spell of milder winter conditions, it is not yet warm enough to grow the commercial varieties of passion fruit (Passiflora edulis) outdoors, even in sub-tropical districts of Worcester.

I was about to write “edible”

varieties of passion flower but, of course, you can eat the fruits of our hardy passion flower (Passiflora caerulea), although just trying one is more than enough for most people. Generally they are not very nice.

Your new plants are natives of South America – Brazil I believe – so they really need to be kept in a greenhouse and, as they grow like mad, a fairly large one would be good.

You’ll get the typical passion flower type of bloom, in greenish white, then along come the generally purple egg-shaped fruits, which tend to become brownish purple and wrinkle a little when ripe.

This is why another name for the edible passion fruit is Purple Granadilla. Although, as I’m not sure which type of fruit you bought, there is also a yellow version (P.edulis flavicarpa) much cultivated in Hawaii and called the Yellow Granadilla.

You could grow your plants quite successfully in containers in the greenhouse, using either multipurpose compost with added John Innes, or use John Innes No3 with about 20 per cent extra composted bark added.

I would start off in a 7in pot and ultimately they would live for years in a 20in pot.

Grow the shoots along wires and the side shoots from these will bear the flowers. In January, before new growth begins, completely remove any weak side shoots and cut the rest back hard to leave two buds.

These will produce new fruiting growth.

Bear in mind that, as you have already discovered with your hardy plants, perennial, fruiting plants grown from seed are likely to be very variable in cropping performance and some are unlikely to crop much at all. This is why commercial crops will be propagated vegetatively.

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