Do you remember the last real heatwave summer? Weeks without rain, temperatures above 35 degrees Celsius, and pure drama in the garden: wilting leaves at noon, cracked earth, plants that never really seemed satisfied despite daily watering.
That wasn't bad luck. That was a soil issue.
Because the soil determines how long water remains available – not the garden hose. If you have soil that stores water and releases it gradually, you water less, harvest more, and sleep more soundly when the next heatwave comes. And it will come. That is no longer a question, but a reality.
In this article, we'll show you how to make your garden heat and drought resistant step-by-step – with natural methods that really work.
Why conventional soils fail in heat
Imagine your garden soil like a sponge. A good sponge absorbs water, holds it – and slowly releases it. A bad sponge is either rock hard and simply repels water, or it's so loose that everything drains right through.
Most garden soils, especially sandy or heavily cultivated ones, fall into the second category. Water quickly infiltrates or evaporates from the surface before roots can reach it. In heat, this becomes a real problem: the earth dries out in hours, the plant becomes stressed, and you're out there with the watering can twice a day.
In addition: dry soil loses its structure. It becomes hard, compacts, and with the next watering, the water hardly penetrates – it simply runs off to the side. A vicious cycle.
What you need is soil that stores water like a reservoir and releases it when needed. This is exactly the idea behind targeted soil improvement with zeolite.
What zeolite specifically does in heat
Zeolite is a volcanic mineral with a unique, highly porous structure. Imagine tiny sponges that can absorb and hold water – that's essentially zeolite in the soil.
Scientific studies show that soils with added zeolite retain significantly more water than untreated soils. In practice, this means: after watering or a rain shower, water remains available longer in the root zone, instead of immediately seeping away or evaporating.
But zeolite can do even more: it binds nutrients like potassium, calcium, and ammonium – precisely the substances that would otherwise be quickly washed out with intensive watering. Especially in summer, when you water a lot, this is crucial: the plant not only gets water but also remains well supplied with nutrients.
And another effect that many people don't consider: zeolite improves soil structure. Well-structured soil doesn't compact as quickly, allows water to penetrate better – and doesn't form a hard crust that simply causes rain and irrigation water to run off.
Mulching: The underestimated heat protection
Before we get to the specific measures, one more point that is often underestimated: mulch.
A 5-10 cm layer of mulch on the bed is worth its weight in gold in summer. It reduces evaporation from the soil surface by up to 70%, keeps the soil cooler, and protects soil life from direct sunlight. Straw, grass clippings, bark mulch, leaves – anything is better than bare soil.
Mulch and zeolite complement each other perfectly: zeolite stores water deep in the soil, and mulch prevents it from evaporating from the top. Together, you halve your watering needs – without your plants suffering.
Step-by-step: How to make your garden climate-proof
Step 1: Analyze and understand your soil
Before you buy or incorporate anything, look at your soil. Press a finger into it – how far does it go? Is the soil still wet after a rainy day, or is it dry again? Does a puddle form after watering, or does the water quickly soak in?
Sandy soils dry out quickly and require more zeolite for water retention. Loamy soils retain water better but tend to compact – here too, zeolite helps by improving the structure. Humus-rich soils are already in good shape but can benefit from a supplement.
Step 2: Incorporate BODENKRAFT Zeolith PUR
Our BODENKRAFT Zeolith PUR – activated zeolite in the optimal granulation for garden use – is your most important helper for heat-resistant soil.
For vegetable or perennial beds, we recommend 1–2 kg per square meter, worked into a depth of 10–15 cm, when starting a new bed. For existing beds, a maintenance amount of 300–500 g per square meter, lightly hoed in, is sufficient. Once properly incorporated, zeolite remains in the soil permanently – you don't have to repeat the basic treatment every year.
Step 3: Build up organic matter
Zeolite is a storage unit – but it needs something to store. Always combine it with organic material: well-rotted compost, horn meal, or manure. The organic matter provides nutrients and further improves soil structure. Zeolite then ensures that these nutrients are not immediately washed out.
Rule of thumb: A bucket of compost and a handful of BODENKRAFT PUR per planting spot – that's a good basic setup for the summer season.
Step 4: Activate soil life
A living soil is a resilient soil. Soil organisms – bacteria, fungi, worms – improve soil structure, make nutrients available, and help plants grow well even under stress.
This is where our AM PLUS comes in: active microorganisms that specifically build up the soil microbiome. In heat-stressed soil that often dries out, soil life suffers particularly. AM PLUS helps stabilize this balance – and works excellently with zeolite because the porous zeolite structure provides an ideal habitat for microorganisms.
Step 5: Rethink your watering strategy
This sounds trivial, but it makes a huge difference: water in the morning, not at noon or in the evening. In the morning, the water has time to soak into the root zone before the midday heat evaporates it from the surface. Evening watering keeps the leaves wet overnight – which promotes fungal diseases.
And: water less often, but thoroughly. Daily shallow watering keeps roots near the surface – precisely where it's hottest and driest. Infrequent, deep watering forces roots to grow deeper – where it's cooler and moister. Coupled with zeolite-improved soil that holds water longer, twice a week is often sufficient.
Specifically protecting particularly heat-sensitive plants
Some plants are particularly susceptible to drought stress – and deserve special attention:
Tomatoes and peppers react extremely to water fluctuations. Blossom end rot, fruit splitting, blossom drop – all symptoms of uneven water supply. Here, a particularly good planting hole with plenty of BODENKRAFT PUR is worthwhile.
Lettuce and spinach bolt to seed immediately in heat. This cannot be entirely prevented, but cooler, consistently moist soil significantly delays it. Mulch and zeolite help – and a shady location, of course.
Herbs like basil or parsley do not like extreme temperature fluctuations in the soil. Especially in pots and containers, they are at risk – here, a substrate with zeolite content is almost mandatory.
Berries and fruit trees suffer in summer primarily from competition: when the soil dries out, they struggle with weeds and other plants for the little available water. Well-prepared soil with high water storage capacity makes the difference between a good and a poor harvest here.
What you should NOT do in the heat
A few classics that are well-intentioned but counterproductive:
Do not water in full sun. Most of the water evaporates immediately before it can penetrate the soil. Additionally, water droplets on leaves can act like small magnifying glasses.
Do not water a little daily. Better to water infrequently and thoroughly – this promotes deep root growth.
Do not dig up the soil when it's bone dry. This completely destroys any remaining soil structure and makes evaporation even worse.
Do not plant fresh plants in peak heat. If you can avoid it, do not transplant new plants during hot weather. The transplant shock plus drought stress is too much at once for many plants.
The big advantage: You work once – and benefit for years
The beauty of good soil improvement is this: You do it right once, and your garden becomes permanently more resilient. Zeolite remains in the soil, the structure improves over years, and soil life establishes itself.
In the first year, you'll already notice a difference. In the second year, your soil will be noticeably different. And after a few years, you'll have a garden that will cope with even a crazy heatwave summer much better than your neighbors'.
This is not magic. It's simply soil that works as it should.
If you want to get started: you can find BODENKRAFT Zeolith PUR and AM PLUS in our shop – and if you're unsure how much you need for your bed, just write to us. We're happy to help.
Happy harvesting – even when it gets hot again. 🌞
→ You can find what can naturally support your garden soil in our Garden Collection.
About the Author
Michaela Schirmbrand-Pfeiffer is an entrepreneur, coach, and co-founder of STEINKRAFT. Her passion: the potential of both people and the earth. She believes that the earth unfolds itself – if we give it the right space. In her garden blogs, she shares knowledge that enables better decisions: for healthy soil, nutritious food, and a life in harmony with nature.
