After the Ice Saints: safe planting in May

Why wait for the Ice Saints?

The Ice Saints are named after three saints (Saint Mamertus, Saint Pancrateus, and Saint Servatius) whose feast days fall around May 11-13. This date is not arbitrary: it marks the statistical point where the risk of nighttime frost in Northern Europe drops below 5 percent. For gardeners, this is the green light to plant frost-tender crops.

Classical garden sayings like "No frost after Pinwhitsunday" are age-old wisdom. They still hold true. For tomatoes, peppers, basil, courgettes, melons, and other heat-loving plants, this is the tipping point. For cautious gardeners: wait until May 20th or later.

Which plants are frost-tender?

Not everything can go out after the Ice Saints. Some vegetables and flowers tolerate frost; others do not. Here is the definitive guide.

Very sensitive (plant after May 20th):

• Tomatoes (all varieties)
• Peppers and chilli peppers
• Aubergine
• Courgettes and melons
• Cucumbers
• Basil
• Cardamom

Moderately sensitive (plant after May 15th):

• Beans (snap beans, runners)
• Maize
• Courgette seeds
• Pumpkin
• Peas
• Summer-flowering annuals (sunflower, Zinnia, Cosmos)

Frost-hardy (can plant earlier):

• Potatoes
• Cauliflower, broccoli
• Leek
• Lettuce
• Spinach
• Garden peas
• Anemone, tulips, daffodils (winter bloomers)

March-April preparation

The real work happens before planting. Three to six weeks before planting day, lay the foundation.

Growing medium: The soil where you plant must be fertile. In March, work in compost or organic soil improver. For containers: use potting soil with slow-release fertilizer. For vegetable rows: ensure at least 5 cm of compost in the top layer.

Hardening off: Begin in April with "hardening off" of seedlings. This means: if you have raised seedlings indoors, place them outdoors on warm days to gradually acclimatize them to outdoor climate. Place them outside in the morning, bring them in at night. After two weeks they can stay outside overnight (if no frost threatens).

Soil temperature: Check soil temperature. Warm-loving crops like tomatoes want at least 15-16 degrees Celsius. Many gardeners wait until late May to be certain.

Step-by-step

Step 1: Mark your planting lines and distances

Measure your vegetable beds. Draw chalk lines for rows. Keep notes on spacing: tomatoes 60 cm apart, peppers 45 cm, beans 20 cm. This prevents overcrowding.

Step 2: Harden off your seedlings

Ten to fourteen days before May 15th, start bringing seedlings outdoors. Set them in warm spots (against south-facing walls, on bricks), bring them back inside during frost or storms.

Step 3: Prepare your beds

Work compost in, make furrows for seeds, position cuttings of sturdy young plants. Make holes large enough for root balls.

Step 4: Plant and water

Set plants in their holes, replace soil, press gently. Water deeply immediately so roots contact soil.

Step 5: Protect the first night

On the night of May 14-15 (and one or two nights more), you can cover young plants with burlap or non-woven fabric. This prevents damage.

Timing per crop

Frequently asked questions

What if frost comes after May 15th?

In Northern Europe, nighttime frost after May 15th is rare (less than 5% chance) but not impossible. Watch the weather forecast. If frost threatens anyway: cover plants with old sheets, burlap, or non-woven fabric (frost cloth). This protects against light frost. If it is really severe: move plants back inside or into a greenhouse until it passes.

Can I plant seedlings directly outdoors without hardening off?

Not recommended. Seedlings raised indoors burn quickly in strong sun and shrivel from wind. Always do two weeks of hardening off. This results in stronger, less damaged plants.

How deep do I plant seedlings?

Tomatoes: plant slightly deeper than they were in the pot (underground stem becomes roots). Peppers, courgettes: plant at the same depth as in the pot. Beans, maize: plant hole exactly as deep as the seed is long.

What compost do I use best?

For seedlings in pots: seed compost (fine, nutrient-poor, sterile). For vegetable beds: full potting compost (decomposed potting mix, garden compost, or shop-bought quality soil). Avoid soil improver with high nitrogen - that gives lots of leaf but fewer fruits.

Can you also sow directly outdoors after the Ice Saints?

For beans, maize, courgettes, cucumbers: yes, you can. Sow seeds three weeks after the Ice Saints directly in soil. This saves seed-raising work and is stronger against diseases. For tomatoes, peppers, aubergine: too slow - you will not get a crop. These must be seedlings.

Protection against frost damage

Night covers: Keep old sheets, burlap sacks, or white non-woven fabric ready. Cover plants on cold nights.

Hilling up: For potatoes and beans: create a mound (ridge) instead of furrows. Heat is retained better in ridges.

Mulch: Lay 5 cm of mulch (straw, shredded leaves) on vegetable beds. This provides extra insulation against cold.

Plastic: Black plastic on the soil raises soil temperature several degrees. Good for warm-loving crops.

Month focus: May tasks

After the Ice Saints, May becomes hectic. You plant everything you have prepared. At the same time, weeds start growing, first insects appear, and you must water (dry May is dangerous). Plan two to three full garden days in May.

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