Grow your own: May

Grow your own: May

by Nick Harman 6 May 2016

The green-fingered Nick Harman focuses on potatoes, tomatoes, squashes and beans during May, with expert tips on what to plant outside when.

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Nick Harman combines work as an advertising copywriter with writing and photographing stories around food and travel.

Nick Harman combines work as an advertising copywriter with writing and photographing stories around food and food and travel. Both jobs happily involve long lunches and too much wine. When not indulging himself he can be found digging his allotment and muttering darkly about account handlers, slugs and other annoying pests.

I hope the soil is warming up where you are, as we finally get some consistent sunshine. It’s certainly been a long winter and many of us may still get caught out by nasty late frosts, especially after cloudless days. If you have potatoes in the ground or in bags on a patio, then you may have already seen the leaves of those brave plants ‘burnt’ by frost and looking black and sad. It shouldn’t be a disaster – it’ll set them back a few weeks but new growth will appear. Wait and see.

In any case, draw earth up around the plant’s stems and semi-bury them. This always seems a bit violent and destructive but serves good purposes; each buried leaf stem will become a stem that grows a spud instead. It also protects leaves from any further frost damage and helps make sure no spuds will later be exposed to daylight as they grow and swell underground. Daylight turns spuds green and, to a degree, poisonous. Plan to earth up a few more times this month before letting the plants grow on.

If you have grown tomatoes from seed, now is the time to start tentatively letting them go outside during the day – but bring them back inside at night. As the month progresses you can begin to leave them outside at night too, as this process gradually ‘hardens off’ the plants ready to go in their permanent beds later. If you haven’t got any plants from seed, then get some from the garden centre but if they were inside when you bought them, apply the same rules. Putting them straight into your plot could result in them keeling over dead in days.

Courgette seeds
Plant courgette seeds in pairs, then pinch off the weaker of the two once they sprout
Courgette plant
They'll grow fast and reward you with plenty of tasty courgettes


Now is the time to start your courgettes, squashes and pumpkins. I have found these are very susceptible to cold nights and, while these won’t kill them, they will simply stop growing and become all but useless. So if you have plants from the garden centre, wait to plant them out. In my experience even when putting these plants out in late June I have seen them grow strongly and easily outstrip those put in earlier.

Put two seeds of each variety on their edge about a centimetre down in a small pot of seed compost, damp down, cover with a freezer bag and put on a sunny windowsill. As soon as they break the surface, take off the bag and then pinch off the weaker of the two. Keep rotating the pot, or use the tinfoil method I mentioned last month to stop the plant leaning toward the indirect light and getting ‘leggy’. When they do that they can snap easily when transported, being planted or just in a gust of wind.

I grow basic courgettes for safety and also Algerian or ‘grey’ courgettes, which have great flavour, but can be a bit tender to cold weather. I love butternut squashes because if you have a large space they trail everywhere suppressing weeds and can be left pretty much alone until the late autumn. After that, the leaves will all die and the squash skins turn tough, ready for storing somewhere cool and dry to last until at least January.

Grow some Halloween pumpkins just for fun. They don’t taste of much so I don’t bother eating them, but size is everything. For impressing friends try a Turk’s Turban – it looks amazing and tastes pretty good too.

Runner bean
Once runner bean plants are six inches tall, take them outside and grow them alongside bamboo poles
Freezer bag
Placing a freezer bag over seedlings helps protect them from the elements


No English garden is complete without runner beans. I sow them an inch deep, six to a medium sized pot, and get them started inside before moving them outside as soon as possible in May. Once they have reached about six inches high they can be tipped out of the pot, gently separated (remember to only hold them by their leaves) and planted one to a pole against a wigwam of six-foot bamboo canes. Tie the plant tops very loosely to the cane and they will quickly grab on and start winding their way up.

French beans hate cold earth, so don’t even think about sowing them outside until you can stick your finger into the soil down to the second knuckle and not wince. Don’t plant too many; sow in succession from now until late June at least and you’ll avoid gluts. Purple ones look pretty but they turn green when cooked, while I find yellow ones tend to be a bit tasteless. All French beans are best picked as young as possible – if you can’t eat them pick them anyway and use them for compost. If one bean gets to form seeds, the whole plant will shut down.

I'm putting out some mangetout that I started in a cold frame a few weeks back. You can plant some seeds directly when the earth warms a bit. I prefer them to peas because you get more food from less space as you ‘eat all’ plus you can also eat them far smaller and sweeter than the ones you buy. Brilliant in stir-fries added at the last minute, as they need almost no cooking and stay crisp.

Sweetcorn is delicious when eaten within fifteen minutes of picking, before the sugars start to turn to starch. Young plants don’t like being transplanted but if you want to get some started indoors, use pots made out of biodegradable material. These can be planted straight into the earth later with no disturbance to the plant. Otherwise, put seed straight in the ground, aim to plant a block of at least four to six plants and cover each with half a plastic litre bottle to create a mini greenhouse. Wash your hands after, as sweetcorn seeds can often be sprayed with a nasty pesticide. You can buy clean varieties, though.

May is a great season, so get planting and soon – very soon – you’ll begin reaping rewards.

French beans hate cold earth, so don’t even think about sowing them outside until you can stick your finger into the soil down to the second knuckle and not wince.

Nick Harman