May 12, 2026 · by Stachi · 2 min read
Watering a raised bed in summer — how often, when, with what
In high summer, water is the only limitation. Raised beds dry faster than ground beds. How to find the right rhythm and spot heat stress.
In July there's a moment where I have to water daily. For ground beds, watering deeply twice a week beats daily shallow watering. For raised beds, that's different.
Why raised beds dry faster
The soil in a raised bed is surrounded by air on 3-4 sides. Evaporation works through all walls, not just the surface. At 30 °C and full sun, you lose around 10-15 L of water per day from a 100×100×40 cm bed — sometimes more in heat waves.
In a ground bed, soil depth buffers it. Even with a dry surface, 30 cm down there's still moisture. In a raised bed, there's air underneath too.
How often to water
Spring (April-May): every 2-3 days. Soil still cool, moderate evaporation.
Early summer (June): daily evenings, or every other morning.
High summer (July-August): DAILY in the evening. On days above 30 °C an extra morning watering may help (especially for tomatoes, cucumbers, zucchini).
Late summer (September): back to every 2-3 days.
When to water — time of day
Evening is the standard. Soil + plant absorb overnight, cooler air = less evaporation.
Morning is the second-best option. Plant is hydrated when the heat arrives.
Midday is the worst time. Water drops on leaves act like little lenses → burn marks. ~50% of water evaporates before reaching the soil.
What to water with
Rainwater: best water for plants. If you have a barrel, use it first.
Tap water: works. Very hard water makes some plants (blueberry) suffer. Most varieties don't care.
Drip line / irrigation system: saves 30-40% water because less evaporates. Worth the investment from 3+ beds.
Spot heat stress
Before a plant truly dries out, it gives signals:
- Wilted leaves at noon, firm in the evening = normal, plant doesn't pump water at peak heat. Don't panic-water.
- Wilted leaves evening + morning = real water deficit. Water immediately.
- Brown leaf edges = chronic deficit over recent days. Increase rhythm.
- Tomatoes splitting = irregular watering (alternating dry and wet). Water more consistently.
Mulch — the game changer
3-5 cm of mulch (straw, grass cuttings, bark) on the soil:
- reduces evaporation by 50-70%
- keeps soil cooler
- prevents soil crusting
I mulch in June and it saves me 2-3 watering trips per week into high summer.
My summer plan
- Early June: spread mulch
- Install drip line (or watering can + daily ritual)
- Irrigation timer for holidays (1 day = 5 L per bed automatically)
- Heat waves: shade cloth (40%) for 3-4 days over lettuce and tomatoes
In our plant library you'll find each variety tagged "drought-tolerant" or "thirsty". Stachi groups similar water needs into sensible bed sections in the planner.
Water is the only raised-bed limitation in summer. Once you've solved it (mulch, drip, evening routine), everything else is easy.
I'm going to check on the tomatoes. They looked a bit limp at noon today — but that happens in heat. We'll see this evening.
🦔 Stachi
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