"then May bursts, the rainbow of the months"
What Seeds to Sow In May; Inside and Outdoors for a Productive Garden
May is one of my favourite months in the garden. The soil is warming up, the days are longer, and everything feels full of possibility. I find myself spending more time outdoors in the sunshine, sowing seeds and planting for the summer and even into next year.
Outdoors, I’m sowing hardy crops straight into the soil. Chard and spinach because they’re so reliable. I love growing chard with its vibrant stems and glossy leaves, not just for eating, it’s both ornamental and productive. I sow it directly where it’s going to grow, spacing the seeds out to save myself thinning later. Spinach, on the other hand, can be a bit temperamental if it gets too warm. I try to give it a slightly shadier spot and make sure the soil doesn’t dry out. Picking it as baby spinach leaves, it keeps producing over a long period.
Later in the month, once I’m confident the frost has passed, I turn my attention to runner beans. My favourite, I plant them at the base of a frame against my fence. As they grow, I keep them well watered. In front of them I’ll plant kale and chard with salad leaves (lettuce, sorrel and rocket) along the edge.
Also keeping things simple with salad leaves. Throughout May, I sow small amounts every couple of weeks rather than all at once. That way, I get a steady supply instead of everything being ready at the same time. You could use containers as well as beds, especially for quick crops like rocket and loose-leaf lettuce. Keeping them watered is essential.
If you like French beans sow in rows or small blocks, similarly peas. Sow them in neat drills and set up supports straight away so they have something to cling onto. When they start producing, pick both peas and beans regularly, it really does encourage more pods.
Sowing in Seed Beds
Sprouting broccoli is more of a long-term investment if you have room. Sowing it in May, you know you won’t see the results until much later, often the following year. If that continuity appeals, then start it in a separate seedbed or trays and then transplant it once the seedlings are strong enough. It’s one of those crops that rewards patience.
Cauliflowers are another variety to sow direct in a seed bed. Choose a firm, fertile patch of soil and make shallow drills, sowing the seeds thinly so they have space to develop. You’ll need to keep the soil consistently moist because any stress at this stage can affect how the heads form later on.
Sweetcorn, a popular summer crop, can also be sown outdoors in May, particularly in warmer southern regions. Sow seeds in blocks rather than rows to aid pollination, spacing them about 30–45 cm apart. Sweetcorn thrives in rich, well-manured soil and requires plenty of water as it grows. In cooler areas, starting seeds indoors or under protection may still be preferable to ensure success.
Sowing Indoors, in modules
Indoors, May is the perfect time to sow tender crops that will later be planted outside once the weather is reliably warm. Courgettes are one of the easiest and most rewarding crops. I sow the seeds individually into small pots filled with compost, placing them on their side to reduce the risk of rot. I keep them in a warm, bright location and water regularly. Within a few weeks, they will be ready to harden off before transplanting outdoors into a large container.
Marrows follow a similar growing pattern to courgettes but require more space to reach their full potential. Like courgettes, they prefer warmth and plenty of light during germination and early growth. Squash and Pumpkins, perhaps the most dramatic of the cucurbits, also benefit from an indoor start. Outdoor cucumbers too. Treat them much like courgettes and marrows, giving them warmth and light to get going. As the seedlings grow, they will need space, light, and careful watering. By the end of the month or into early June, you can begin the process of acclimatising them to outdoor conditions. Given enough room and nutrients, pumpkins will sprawl and produce impressive fruits by autumn.
Flowers to Sow Outdoors in May
As the soil warms, many flowers can be sown directly where you want them to bloom. (I have sown some sunflowers in pots, but these can go straight in if the soil is warm later in the month). Cosmos and zinnias are excellent cut for bouquets. Nasturtiums and calendula (pot marigolds) make good companions amongst the vegetables. Poppies and cornflowers bring wildflower vibe into the garden, whilst night scented stocks add fragrance to late summer evenings.
Preparation, Protection and Succession
Before I sow anything, I try to make sure my soil is in good condition. I spend time clearing weeds and layering on compost or well-rotted manure. Good soil makes all the difference, it holds moisture, drains well, and gives seedlings the nutrients they need.
Protection from pests is another consideration. Slugs and snails can be a real problem in May, and I’ve learned the hard way how quickly they can destroy young plants. Barriers, traps, and vigilant monitoring can help keep their numbers in check. Birds may also target newly sown seeds, so netting or fleece can provide useful protection.
One of the most useful habits I’ve developed is succession sowing. Instead of doing everything in one go, I spread my sowings across the month. It takes a bit more planning, but it means I’m not overwhelmed later with everything ready at once.
"January, February and March are like prison walls to the spirit; April comes as a window opened, admitting sunlight and a patch of blue sky; then May bursts, the rainbow of the months, sent as a sign — a promise of fruition." ~The National Magazine, May 1899