The 6 Seeds You MUST Start in May

This is one of the most important times in the gardening calendar! With warmer soil and longer days, suddenly anything feels possible, and what you sow now can set you up both for productive summer harvests and crops for winter too.

So let’s explore the priority seeds to start in May, including those summer superstars, beans and sweetcorn, and winter-hardy staples for the tail-end of the season and beyond – plus a vegetable I’ve never grown before that I’m very excited about!

Winter Squash

Let’s start with a crop that absolutely loves the warmth of late spring: winter squash. Now when I say winter squash, I don’t mean they’ll be grown in winter or even harvested in winter – instead, these are squashes that are harvested towards the end of the growing season in autumn to store right through winter. Think pumpkins, butternuts, acorn squash – all those wonderfully rich, comforting flavours. These types of squash store beautifully, usually for months, which means a single plant can deliver meals long after the warmer months are done.

This year I’m going to grow my winter squash so that the plants sprawl among a stand of sweet corn. Not only will this make the most of space, this pairing is two of the ‘three sisters’, which is a traditional planting method developed by indigenous peoples in North America that brings three crops together to help one another. Beans make up the third ‘sister’, which climb up the tall corn. The beans fix nitrogen into the soil, while the squash spreads at ground level, shading the soil and helping keep weeds down. It’s companion planting at its absolute finest!

I’m growing just two of the three sisters together as my beans are destined for more permanent supports elsewhere in the garden to add vertical punches of interest and to make them easier to pick.

If you’re growing in a warm climate you could sow squashes directly where they are to grow, but otherwise start your squashes off under cover so they get the most warmth. Fill small pots with all-purpose potting mix. Squash seeds are satisfyingly large and easy to handle, so simply push one seed into each pot about an inch (3cm) deep, then cover them over with more potting mix, label the pots, and give them a good drink.

Keep your squash seeds somewhere warm to germinate – perhaps on a greenhouse bench, cold frame, or bright indoor windowsill. Squash seedlings grow quickly, so by the end of the month mine should be sturdy enough to plant out into a sun-drenched bed where they’ll spread out beneath the corn. With plenty of warmth and water through summer, they’ll soon be producing those gloriously chunky fruits, which will be ready to cut free at the end of the season.

Sweet Corn

So next up is the corn for my two sisters, and I’m sowing a super-sweet variety bred for exceptionally sweet, irresistible cobs. Picked minutes before cooking and smothered in butter they’re the definition of sublime! There are plenty of super-sweet varieties available such as Amaize, Damaun, Early Xtras Sweet, Krispy King, Northern Extra Sweet, or Takeoff MXR.

There’s something wonderfully satisfying about growing corn. Watching those tall, elegant stems sway in the breeze is enough to make any vegetable patch feel a little more majestic, and when you enjoy your own super-fresh cobs, my goodness, that sweetness is on another level entirely!

To grow corn with squash we want to get the corn to started away from the final growing area so it can grow on a bit before transplanting – we don’t want those sprawling squash stems swamping our corn. So, with that in mind I sow mine into an all-purpose potting mix in a nice deep plug tray. Deep plugs are ideal to encourage good, deep roots that’ll help the corn settle into position quickly.

Each plug gets one seed, pushed down about an inch (2cm) deep. Corn has roots that grow quickly, so growing in individual plugs (rather than sowing several seeds together in a pot) makes transplanting later much easier, rather than trying to separate tangled up plants.

Once they germinate they’ll grow fast in warm conditions. In just a few weeks these seedlings should be ready to plant out into their final positions. They’re best planted in blocks rather than rows, because corn is wind pollinated. Grow them in long, single rows and the pollen released from the tassels at the top of the plants is likely just to drift off elsewhere. By growing in a block, that pollen is far more likely to be intercepted by the silks further down on neighbouring plants, whichever way the wind is blowing. Each successfully pollinated silk means one more kernel, giving beautifully filled cobs.

Beans

And now for those glorious beans! Climbing beans are a real focal point in any garden because they lead the eye upwards, creating a more three-dimensional and eye-catching feel. Every garden needs an arch, trellis or teepee of beans!

Every year I grow two types of climbing beans: a fine, filet or French bean, and a flatter-podded runner bean. To keep them safe from slugs I start them in pots, rather than sowing them directly into the bed. Just like corn and squash, beans are yet another large, easy seed to sow. Just push one seed about an inch (3cm) deep into each pot, cover them back over with potting mix, label, and water. And that’s it!

Beans grow quickly, and by the end of the month they should be ready to plant out against supports, once there’s no danger of any more frosts. If you’re unsure when your last frost date is, check out the free trial of our Garden Planner, which will show you when to expect it based on your location.

The trick with beans will be regular picking. Only with an almost religious dedication to harvesting will they continue to produce – a happy problem to have!

Brussels Sprouts

Brussels sprouts is a crop I’m particularly excited about this year because (I can’t believe I’m admitting this!) I’ve never grown this winter-hardy staple before! I’m really looking forward to seeing those tall plants develop with their little rows of sprouts stacked neatly up the stems.

Brussels sprouts take quite a long time to mature – often six months or more – which means that, despite being predominantly a winter crop, now is in fact the perfect time to get them off the starting blocks.

Sow the seeds into plug trays filled with potting mix, two seeds per plug. Lightly cover them over and water them. Once the seedlings appear, thin them to the strongest plant in each plug. The young seedlings will grow steadily, and should be ready to plant in four or five weeks.

Plant about 2ft (60cm) apart each way into soil that has already been improved with plenty of compost. Are they worth the space? Well, I reckon they probably are, because homegrown sprouts are of course going to taste so much better than something picked days or even weeks before it hits the supermarket shelves.

They’ll be ready to pick from autumn onwards. If you’re already thinking ahead to Christmas dinner – I always am! – having sprouts you’ve grown yourself on your plate will be a very special moment indeed!

Parsnip

Another winter favourite is the decadently indulgent parsnip. Delicious, slightly chewy, sweet roots that caramelise beautifully when roasted.

There’s little point sowing parsnips into cold ground but if you touch the soil with the back of your hand and it doesn’t feel cold, your parsnip seeds will be quite happy. Warmer soil means the quickest possible germination, which is important since parsnips can take up to three weeks to germinate – sometimes four!

Use fresh seed, because parsnip seeds don’t last for long. Sow them into drills (shallow trenches) about a half inch (1cm) deep and an inch (2-3cm) apart. A little trick is to sow radishes between the rows of parsnips. These sprout super quickly, helpfully marking out the rows, and they’ll be harvested way before the parsnips need the extra space.

The parsnip seedlings are very distinctive, so it’s easy to tell them apart from weeds. I like to remove excess seedlings, then young plants, in stages until they’re eventually 6in (15cm) apart. Then they can be left to pretty much get on with it – this is an exceptionally low-maintenance root crop.

Basil

Few herbs say summer quite like basil, and just brushing past the leaves releases that incredible aroma: sweet, slightly spicy, and unmistakably Mediterranean. It’s the perfect companion for tomatoes, salads, pasta, you name it – and the more you pick it, the more it grows.

Basil seeds are tiny, so sprinkle them as thinly as you can across the surface of moist potting mix and then cover them with a very, very light layer of potting mix – just enough so they disappear from sight. They’ll germinate best somewhere warm, as basil really does appreciate a bit of heat.

Once the seedlings emerge, pot them on into larger containers and, when they’re a bit bigger, into greenhouse borders, or outside if you’re in a warm climate. Regular picking encourages bushier plants and prevents them from flowering too soon, which means even more lovely leaves for cooking. Fabulous!

If you’d like a little help working out exactly when to sow and plant in your garden, do check out our Garden Planner. As well as advising on your last frost date, it’ll give you personalised sowing, planting and harvest times for your area, and you can try it out completely free for 7 days. Happy sowing!

Plants Related to this Article

Squash (Summer) Grow Guide

Corn Grow Guide

Beans (Bush Snap) Grow Guide