CALENDAR – MAY
When the frost retreats and the ground thaws, it's time to sow plenty of flowers and vegetables. This is also the time to plant onion sets and potatoes that can be harvested later. Carrots, lettuce, beets, and much else can now be sown outside without first starting the seeds indoors. And much of what you have started indoors can now be planted outside. But wait a month or two with the plants that are most sensitive to cold, such as melons, peppers, and chilies. Be aware that the timings for when plants should be planted out vary depending on which hardiness zone you live in, and always take weather into consideration – there can still be a frosty night or two. When the time comes to plant out, remember that young, small plants that have grown indoors – even the hardiest ones – need to be gently and gradually acclimated to outdoor life. This is called hardening off. Feel free to use a fleece in the beginning to provide protection to the plants and even out the temperature.
Plant the seeds you can sow outside in May
Spinach
Beets
Carrots
Spring onions
Beans
Bean seeds can be sown now, but wait a little before planting out ready plants.
Peas
Potatoes
Onion sets
Opt for heat-treated onion sets for a better chance of a large harvest.
Lettuce
Dahlias
At the end of May or beginning of June, when the risk of frost is over, it's time to plant out pre-grown Dahlias. Not sure about the weather? Wait a little longer! Dahlias are very sensitive to frost.
Summer flowers
Such as nasturtium, zinnia, corn poppy, decorative sunflower, and summer poppy.
Plant pre-cultivated plants
If you have pre-cultivated plants indoors, you can put out the most hardy ones after you have hardened them off. Hardening off the plants means gradually acclimating them to live outdoors by leaving them outside only during the day for about a week before planting them out for good. However, most plants that are pre-cultivated indoors may need to wait a little longer before they can be planted out. Plants that require the most warmth, such as beans, cucumbers, and squash, must be kept indoors the longest – until summer is in full swing with its 20°C temperatures.
It is often wise to pre-cultivate plants that slugs are fond of. The plants have a better chance of escaping the slugs if they are planted out as larger plants, rather than sprouting from the ground small and tender. If you continuously pre-cultivate lettuce and other leafy greens, you will also have new seedlings to put out as you harvest and make space in the beds and plant boxes outside. If you want to grow fragrant sweet peas, May is the month to get started.