A climate-by-climate guide for flowers that actually suit your garden.
May is the month when the garden starts asking for decisions.
In the south of Europe, the sun is already strong and the soil is warming fast. In the north, spring may still feel new and slightly uncertain. Along the Atlantic coast, rain and mild days can make everything grow at once. Inland, gardeners often move from chilly nights to sudden summer heat in the space of a few weeks.
Instead of asking, “What can I sow in May?”, ask:What should I sow in my kind of May?
If your May is already hot and bright
Mediterranean gardens: Southern Spain, Portugal, Southern Italy, Greece, Cyprus and Malta.
In Mediterranean gardens, May is not a gentle spring month. It is the gateway to summer. The best seeds now are those that enjoy warmth, cope with strong light and do not collapse the moment the weather turns dry.
Cosmos are one of the easiest wins. They grow quickly, flower generously and bring a loose, romantic feeling to borders and cutting patches. Try Cosmos Seashells Red for something striking, or Cosmos Double Dutch White for a softer, cleaner look.
Zinnias are another excellent choice where summers are hot. Zinnia Elegans Dahlia Meteor gives rich colour, while Zinnia Elegans Dahlia Isabellina offers a more muted, elegant tone.
For height, drama and pollinators, sow sunflowers. Choose Sunflower Ruby, Sunflower Claret, Sunflower Buttercream or Sunflower Sunspot.
For something relaxed, edible and slightly wild, add nasturtiums. Good choices include Sahin’s Rumba, Sahin’s Paso Doble and Tiptop Rose.
May sowing tip: Water the soil before sowing, then keep it just moist until germination. Once seedlings are growing strongly, water deeply rather than constantly.
If your May is mild, damp and changeable
Atlantic and temperate gardens: UK, Ireland, Northern France, Belgium, Netherlands and coastal Northern Germany.
In these gardens, May often feels like the month when everything suddenly becomes possible. The soil is warming, the days are long, and outdoor sowing becomes much more reliable.
Start with calendula. It is cheerful, forgiving and useful for pollinators. Calendula Ivory Princess gives a soft vintage look, while Calendula Funky Stuff and Calendula Bulls Eye bring warmer, more unusual tones.
For a meadow or cottage-garden feel, sow cornflowers and nigella. Cornflower Blue Boy is the classic clear blue, while Cornflower Black Ball adds depth and contrast. Nigella Sativa is delicate in flower and beautiful again later when the seed pods form.
If you want easy colour with minimal fuss, add California poppies. Try Eschscholzia Thai Silk Rose Chiffon, Jelly Beans or Thai Silk Formula Mix.
May sowing tip: Thin seedlings early. It feels ruthless, but crowded seedlings become weak plants. Watch for slugs after rain.
If your May cannot make up its mind
Continental gardens: Poland, Czech Republic, Austria, Hungary, Romania and inland Balkan regions.
Continental gardens can be dramatic in May. One week still feels like spring; the next feels like summer has arrived without warning. The best approach is to sow for warmth, but keep a little caution in reserve.
Marigolds are dependable, bright and useful in mixed planting. Tagetes Burning Embers is a strong choice if you want colour with more depth than standard bedding marigolds.
Dahlias from seed are also worth starting in May. Dahlia Figaro Formula Mix is a good all-round choice, while Figaro White, Figaro Orange and Dandy Improved Mix allow for more specific colour palettes.
For evening scent and a softer mood, try Nicotiana Perfume White or Nicotiana Perfume Rose.
Once nights are reliably mild, sow cosmos and zinnias. Cosmos Fizzy Rose Picotee and Zinnia Elegans Dahlia Meteor are good choices for gardens that move quickly into summer heat.
May sowing tip: If late frost is still possible, start tender flowers under cover and move them outside gradually.
If your May is still cool
Northern, Baltic and Alpine gardens: Scandinavia, Baltic states, mountain regions and higher-altitude gardens.
In cooler regions, May is precious. The season is shorter, the soil warms later, and every sowing needs to earn its place.
Begin with poppies. They are well suited to direct sowing and do not like root disturbance. Choose Poppy Lauren’s Grape, Poppy Purple Peony, Poppy Bread Seed or Poppy Dawn Chorus.
Calendula, cornflowers and nigella are also reliable choices in cooler gardens. They are quick, useful and do not require a long hot season to be worthwhile.
May is also a good time to think beyond this summer. Hollyhocks and agastache can be started now to build strong plants. Try Hollyhock Chater’s Double Mix, Hollyhock Jet Black, Agastache Golden Jubilee or Agastache Rose Mint.
May sowing tip: Use fleece or cloches if cold nights return. In short seasons, starting slower plants under cover can give them the extra push they need.
Not sure where to start?
For a romantic cutting patch
Cosmos, zinnias, dahlias and nicotiana.
For pollinators
Calendula, cornflowers, agastache, poppies and sunflowers.
For hot, dry gardens
Cosmos, zinnias, nasturtiums, sunflowers and California poppies.
For cooler regions
Calendula, cornflowers, nigella, poppies and hollyhocks.
