At a glance
- Water less often but deeply: one big can every three to four days beats a little sip every day.
- Early morning is the best time. The water soaks in before the sun can evaporate it.
- Always at the root, never over the leaves: wet foliage in the midday sun invites fungal disease.
- A mulch layer of straw or grass clippings keeps the soil moist and often saves half the watering can.
- The finger test beats any calendar: only water once it is dry two fingers deep.
In high summer you quickly end up in the beds with the can every evening, and still the tomatoes let their leaves droop at noon. That is rarely because you water too little. Usually you water too often and too shallow. Anyone who only wets the top of the soil trains their plants to grow lazy, shallow roots that wilt at the first hot day. Between CW 18 and CW 34, when the sun really has power, it is not the amount of water that decides whether your garden stays relaxed, but the way it reaches the soil.
Why less often and deeper saves half the can
Picture the soil like a sponge. Give it a little sip every day and the moisture stays in the top few centimetres and has evaporated by the midday heat. The roots stay up high, where it dries out fastest. Give it a big portion every three to four days instead and the water sinks in deep. The roots follow it down into cooler, moister layers, and the plant rides out even a hot day without drama.
For most vegetable beds that means roughly 15 to 20 litres per square metre every three to four days rather than two litres every day. After watering you can check with your finger whether the water really reached ten to fifteen centimetres deep. If the soil is only dark on top, it was too little.
Better once properly than three times a little. Deep roots make strong plants.
Old gardener's rule
The best time is early morning
Water before the sun climbs over the fence, ideally between 5 and 8 in the morning. The soil is still cool then, the water soaks in instead of evaporating straight away, and the plants are ready for the hot day. A bed that was soaked in the morning almost always gets through the day without a second round.
Evening is the second best choice, but it has a catch: if leaves and soil stay wet all night, slugs and fungi feel right at home. If it has to be evening, then aim straight at the root and not over the foliage. Midday sun is the worst moment. A large share evaporates unused, and drops of water on the leaves act like little magnifying glasses.
A watering rim of mounded soil around tomatoes, squash or courgette holds the water right above the root ball instead of letting it run off sideways. That way every litre soaks in where it is needed.
At the root, not on the leaf
Plants drink through their roots, not their leaves. Yet in the evening you see sprinklers everywhere merrily showering the whole canopy. That wastes water and invites disease: wet foliage combined with warmth is the entry ticket for late blight on tomatoes or powdery mildew on cucumbers and courgettes.
Drip line instead of sprinkler
For larger beds a drip line pays off. It releases the water slowly and directly onto the soil, with no evaporation into the air and no wet foliage. Hooked up to a simple timer, it waters in the early morning hours while you are still asleep. In a pot, a watering can without a rose, held close to the stem, does the job.
A watering can without a rose, a hose with a gentle stream straight onto the soil, a drip line along the row: all three bring the water to where it counts. The sprinkler stays for the lawn.
Solanum lycopersicum
- Familie
- Nightshades
- Standort
- Full sun, sheltered from rain
- Saison
- Harvest July to October · CW 27 to 43
- Wasserbedarf
- Even, deep, always at the root
- Frosthärte
- Frost-tender
Tomatoes in particular reward even watering with healthy fruit. If the water supply swings a lot, the fruit splits open or gets the dark blossom end rot. Calm and regular, straight at the root, is half the battle here.
Mulch saves half the watering can
If there is one single move that saves the most water in summer, it is mulching. A layer of straw, dried grass clippings, leaves or shredded green waste settles like a blanket over the soil. It holds the moisture down below, keeps the roots cool and suppresses weeds along the way.
How thick the blanket should be
Five to seven centimetres of mulch is ideal. Leave a small collar free around the stem so nothing rots there. Take dry material like straw a bit thinner, fresh grass clippings only a hand thin and dried off, otherwise it turns into a slimy, rotting mat. Top it up once the layer has broken down, usually every few weeks.
The soil under a good mulch layer stays moist noticeably longer. In practice that often means you water only half as often as with an open, bare bed, and the water you save ends up not in the air but at the roots.
The finger test beats any calendar
It is not the day of the week that tells you whether to water, but the soil. Push your finger two knuckles deep into the soil next to the plant. If it still feels moist and cool down there, you wait. If it is dry and crumbly, you reach for the can. That one minute spares you both overwatering and parched beds.
- Leaves droop in the morningIf the plant already looks limp before the midday heat, the soil really is too dry. Leaves drooping at noon over moist soil, by contrast, are just sun protection and no sign of thirst.
- Soil is dry two fingers deepThe most reliable test. Dust dry on top and moist below is perfectly fine. Only when it is dry down deep as well do you water.
- A pot feels feather lightPots and balcony boxes dry out much faster than a bed. A light pot is thirsty, a heavy one still supplied. In high summer, containers often need water daily.
- Fresh sowings and young plantsShallow-rooted seedlings and freshly set plants cannot reach the deep water yet and need smaller, more frequent doses at first until they have rooted in.
Collect rainwater and use it cleverly
The cheapest and most plant-friendly watering can is the one from the rain barrel. Rainwater is soft, lime-free and at room temperature, whereas cold tap water briefly shocks the roots. A single summer downpour on an ordinary garden roof already fills a whole barrel.
Tap the downpipe
Fit a rain collector into the downpipe of the garden shed or cabin. It diverts the water into the barrel and lets the overflow run back into the pipe once the barrel is full.Cover the barrel
A lid or fine mesh keeps out leaves, algae and above all mosquito larvae. Dark barrels keep the water cooler and clearer of algae than transparent ones.Scoop with the can or fit a tap
An outlet tap just above the ground makes filling the can easy. If you like, hook up a small pump to feed a hose directly.Link several barrels
Connect two or three barrels with a short piece of hose at the bottom. That way they catch the big downpour together instead of losing it over the overflow.
During long dry spells some municipalities temporarily enforce bans on garden watering from the drinking water supply. A full rain barrel makes you independent of that and, as a bonus, is easy on your wallet.
Containers and balconies need their own rules
On the balcony and terrace the summer rules apply in a sharper form. Soil in a pot heats up all around and dries out from every side. In high summer, daily watering is normal here, on hot days even morning and evening. A saucer keeps a few hours of reserve on hand but should not stand permanently full after watering, or the roots will rot.
Larger vessels dry out more slowly than small ones, and dark pots heat up more than light ones. If you are on holiday, group the containers together in light shade and put a mulch layer or a damp cloth on the soil. Clay cones with an upturned water bottle or a simple watering fleece bridge a few days reliably.
Common questions about watering in summer
Common questions about watering in summer
How often do I need to water in summer?
Is it better to water in the morning or the evening?
Why do my tomatoes droop at noon even though the soil is moist?
Does mulching really save water?
Can I use cold tap water straight from the hose?
Spotted a mistake?
