Gardner’s Diary: what vegetables to sow in May

courtyard garden bathed in sunlight

In her monthly column, organic grower Claire Ratinon shares what to sow in May, from cucumbers to beans.

Claire Ratinon: May is a time of overflowing energy in the garden but between all the shuffling around of tender plants and keeping on top of never-ending weeding, take a moment to pause, draw in a deep breath and look around.

Before I get stuck into my list of gardening tasks for the day, I like to take a slow walk around my growing space with a cup of tea and see what’s changed since I last had a peep. Making time to observe is part of the magic of growing plants and it gives you an opportunity to really notice what nature is getting up to and how best to involve yourself as a gardener.

If you’re anything like me, you’ll have spent the last month checking on your seedlings and watching their every tiny move as they grow up. I’ve been looking every day for the first appearance of true leaves and carefully removing the dandelion seeds that have drifted in through the window and settled next to their slowly widening stems.

The evenings are getting longer as the spring bulbs and blossoms wither and fade and warm sunny days are becoming more frequent. The plants have got the message and are gathering pace in anticipation of a fruitful season ahead.

So, now’s a good time to be thinking about plants that bear fruit as we wait for the soil to warm up enough to welcome them.

What to sow indoors in May
If I was a braver food grower – or if I had a greenhouse or polytunnel – I might already have sown my courgettes, squash and cucumbers. But I’m not! So, I sow my seeds in early May. I’ve found that sowing these heat-loving plants when the days are longer and the temperature doesn’t drop as low as it does in April is a good choice for a home gardener.

Cucurbit seeds such as pumpkins and squashes are on the larger side and benefit from a soaking in warm water for a few hours (and overnight if you have the time) to kick start the germination process. I sow mine in small pots because once they germinate, they grow at quite a speed. Sow the seeds on their side and push them fairly deep in the compost, at twice the depth of the size of the seed. Keep the compost moist but not sodden and place somewhere warm because cucurbits need to be kept at a minimum of 16°C to get the message that it’s time to come out of hibernation.

Now is also a good time to sow bean seeds as they too grow quickly and will be ready to be planted out in no time. Whether you want to grow runner beans, climbing beans or dwarf French beans, bear in mind that they grow long roots rapidly and don’t like them to be disturbed, so sow your seeds in root trainer modules or recycled toilet roll tubes. Beans are less needy when it comes to warmth for germination and should sprout readily at room temperature.

After a bit of a slow start, my tomato plants are filling out. Since it’s still a bit too soon for them to be planted outdoors, I’ll be potting them on into slightly larger containers with extra compost. Repotting is how we buy a little more time for our tomatoes (and other temperature sensitive plants) to grow on with protection but without them running out of space and nutrients in their pots. One magic thing about tomatoes – which isn’t true of other plants – is that each one of those fuzzy little hairs along the stem has the potential to develop into a root so you can bury them deep in fresh compost and it should encourage them to grow a stronger, more anchored root system.

What to grow outdoors in May
The lettuce and beetroot I sowed in March and early April are ready to be planted out in the outdoor beds. Before I do this, I’ll spend a week or so incrementally exposing them to life outside (except in really appalling weather). I place them outside in the sunlight and breeze for more time day after day and then I’ll plant them into their final positions. This process is called hardening off and it lessens the impact of the shock that young plants sometimes experience when going from a relatively cosy existence to braving the rest of their life in the great outdoors.

The peas I sowed directly have germinated well and are starting to push out their little tendrils so by the end of the month, I will set up some netting or give them some knobbly twigs to scrabble up as they grow.

Gardening tasks in May
The seed potatoes you planted last month should be growing bright green leaves above ground by now so be sure to regularly earth them up. By covering the emerging growth with mulch, you will be telling the plant to develop potatoes along the now buried stem. It may feel counter intuitive to cover such luscious new leaves with compost or soil but that’s the way to guarantee a harvest.

It’s still an unpredictable time weather wise so keep a close eye on the forecast and fleece your tender plants if the temperature starts to dip.

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