What to Plant
in May
May is the most important month in the garden across Central Europe. After the Ice Saints pass on May 15, the full growing season opens — tomatoes, cucumbers, courgettes, basil and much more can finally go outside.
Ice Saints — the key date in May
May 12–15 is statistically the last frost risk in Czech Republic and Central Europe. Do not plant frost-sensitive crops (tomatoes, peppers, cucumbers, basil) before May 15. After the 15th, night temperatures consistently stay above 0°C and the full season is open.
Early May (1–14): frost-hardy crops
These crops tolerate light frost and can go in from May 1st. Many were started indoors in March–April and are ready to transplant.
🥦 Vegetables
Transplant or direct sow
Plant out seedlings from April. Direct sow every 2–3 weeks for a continuous harvest through summer.
Direct sow
Sow thinly in rows. Germination takes 2–3 weeks. Keep soil moist until seedlings emerge.
Direct sow
Sow in clusters of 3–4 seeds, 20 cm apart. Thin to the strongest seedling once established.
Direct sow
Ready in 3–4 weeks. Perfect for filling gaps between slower crops. Sow successionally every 2 weeks.
Direct sow
Sow 5 cm deep, 8 cm apart. Add a support structure — even short varieties benefit from twiggy sticks.
Transplant
Harden off indoor seedlings first. Space 40–60 cm apart. Net against pigeons and cabbage white butterflies.
Transplant or direct sow
Fast-growing brassica, ready in 6–8 weeks. Plant 25 cm apart and harvest before the bulb gets woody.
Direct sow
Sow now before summer heat causes bolting. Keep well watered. Harvest outer leaves continuously.
Direct sow / transplant
Sow spring onions thickly in bands. Transplant leek seedlings 15 cm apart in deep holes.
🌿 Herbs (frost-tolerant)
Divide clumps or sow direct. One of the hardiest herbs — tolerates frost well.
Slow to germinate (3–4 weeks). Sow direct or transplant. Flat-leaf has more flavour than curled.
Direct sow where they are to grow — both resent being moved. Sow every few weeks for continuous harvest.
The Ice Saints have passed
Once May 15 is behind you, it's safe to plant everything frost-sensitive. This is the most exciting planting window of the year.
Tomatoes
Plant outdoors only after May 15. Choose a sheltered, sunny south-facing spot. Space plants 60–80 cm apart. Cordon (indeterminate) varieties need staking immediately.
Need warmth and shelter. Plant after May 15 in rich, moist soil. Outdoor varieties tolerate more wind than greenhouse types.
Even more heat-hungry than tomatoes. In colder gardens, grow under a cloche or against a south-facing wall.
Fast-growing once established. Give them plenty of space — each plant can spread 1–2 m. Water at the base to prevent mildew.
Plant in blocks (not rows) for good pollination. At least 4×4 plants. Direct sow or transplant carefully — roots resent disturbance.
Direct sow after May 15. Set up a support structure before sowing. Harvest regularly to keep plants producing.
The most heat-demanding of all vegetables. Best in a cold frame or polytunnel in Czech climate. Outdoors only in warm sheltered spots.
🌿 Tender herbs — after May 15
The most frost-sensitive herb. Even a chilly night below 8°C causes blackening. Plant outside only after May 15 in a warm, sheltered spot.
Mediterranean herbs love sun and well-drained soil. Excellent in containers on a south-facing balcony. Perennial if given a sheltered spot.
Plant in the sunniest, driest spot you have. Borderline hardy in Czech Republic — overwinter in a pot under cover to be safe.
Flowers for May
May is the last big sowing window for summer annuals. Direct sow now for colour from July to October.
Direct sow May 1–20. Best results from direct sowing where they will flower — deep roots resent transplanting.
Hardy annuals — can go out early May. Great companion plant alongside tomatoes to deter whitefly and aphids.
Sow direct from mid-May. Edible flowers and leaves. Thrives in poor soil — too rich and you get leaves but few flowers.
Sow after May 15 in a sunny spot. Feathery foliage and flowers from July to first frost. Cut regularly to prolong flowering.
Plant tubers after May 15. Rich soil, full sun. Spectacular from July. Lift tubers before first frost in autumn.
Plant corms after May 15. Stagger planting every 2 weeks for succession of blooms through summer.
First harvests in May
Ready to pick this month
- ✓Asparagus — the harvesting window is open from late April. Stop cutting on June 21st to let plants build strength for next year.
- ✓Radishes sown in March/April — check every few days, they can go from perfect to woody quickly.
- ✓Lettuce & spring onions from April sowings — harvest outer leaves for cut-and-come-again.
- ✓Spinach and sorrel — young leaves at their best before summer heat arrives.
- ✓Rhubarb — the main harvest month. Do not pick more than half the stems from any one plant.
- ✓Strawberries — late May sees the first ripe berries from June-bearers.
Key May tasks
- →Harden off all indoor-grown seedlings (leave outside in shade for a few days before planting)
- →Water in the morning to reduce evaporation and fungal disease
- →Stake tall plants before they need it, not after
- →Net brassicas against cabbage white butterfly eggs from May onwards
- →Thin direct-sown carrots, beetroot and parsnips once 5 cm tall
Frequently asked questions
When is it safe to plant tomatoes outdoors in Czech Republic? ▼
After May 15. The Ice Saints (Czech: Ledoví muži) on May 12–15 mark the last statistically likely frost in Czech Republic. Planting tomatoes before this date risks losing your seedlings to a late frost. After May 15, night temperatures consistently stay above 0°C in the lowlands.
What can I plant in early May (before the 15th)? ▼
Frost-hardy crops are fine before the 15th: lettuce, spinach, radishes, carrots, beetroot, peas, kohlrabi, cabbage, broccoli, kale, spring onions, parsley, chives and dill. These tolerate light frost down to −3°C or lower.
What are the Ice Saints? ▼
The Ice Saints (Czech: Ledoví muži, Polish: Zimna Zośka, German: Eisheiligen) are a folk weather phenomenon observed on May 12–15 each year in Central Europe. They correspond to the feast days of Saints Pancratius, Servatius and Boniface. Meteorologically, they represent the last reliable cold spell caused by cold air masses from northern Russia. Czech gardeners have used this date as a planting guide for centuries.
Can I grow tomatoes in Czech Republic without a greenhouse? ▼
Yes — Czech summers are warm enough for outdoor tomatoes, especially in Bohemia and South Moravia. Choose an early or mid-season variety rated for zone 5–6. South Moravia (around Brno, Znojmo) has a climate ideal for tomatoes. The key is planting after May 15 and choosing a sunny, sheltered, south-facing position.
What is the Czech Republic's USDA hardiness zone? ▼
Most of Czech Republic is USDA zone 5b to 6b. Prague and the Elbe lowlands are typically zone 6a (minimum −20 to −18°C). South Moravia can reach zone 6b. Mountain areas (Šumava, Krkonoše, Jeseníky) drop to zone 5a or lower. For planting guides, zones 5–6 covers most of the country.
Keep track of your May planting
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