Using biostimulants in hot weather: protecting crop performance

This summer has already brought a stretch of unusually hot and dry weather across the Netherlands and other parts of Europe, and July often pushes crops to their limits. After a promising start to the season, sudden heatwaves or dry spells can disrupt growth patterns and trigger stress. Plants respond visibly: leaves close to conserve moisture, growth slows, and fruit development stalls.

That’s when a solid preparation makes all the difference. Growers who applied biostimulants early in the season have given their crops the tools to handle stress, thanks to the gradual, protective effect these products build over time. Even a targeted application shortly before an expected period of heat or drought can provide meaningful support.

What heat stress does to your crop

High temperatures and dry air can lead to:

• Increased evaporation: stomata close to reduce water loss, slowing down photosynthesis.
• Reduced nutrient uptake: with less water moving through the plant, nutrients are absorbed less efficiently.
• Higher risk of sunburn: especially on exposed fruit and leaves.
• Cell stress:  weakened cell walls can result in misshapen fruit or premature leaf ageing.

These symptoms show up differently depending on the crop:

• Pears: sunburn and surface damage are more common, reducing shelf life and storability.
• Potatoes: heat may cause cracking, uneven tuber formation, and lower storage quality.
• Field vegetables like lettuce, leek or cabbage: growth slows, and tip burn or leaf-edge damage appears.
• Greenhouse crops such as peppers or tomatoes: fruit set is delayed, and blossom-end rot or malformations become more likely

The challenge with heat stress is that symptoms aren’t always visible at first. But over time, they leave their mark, trough uneven fruit sizes, reduced yields, or more losses at harvest and storage.

Why using biostimulants in hot weather matters

If you haven’t worked with biostimulants before, you might recognise some of these signs:

• Fruit is shrivelling faster than usual.
• Leaves look limp or less vigorous despite proper fertilisation.
• You feel the crop is lacking something, but can’t quite identify what.

These are often signs of invisible stress. Using biostimulants in hot weather helps crops cope by supporting vital processes like nutrient uptake and protein synthesis. While they won’t fix damage that’s already done, they can reduce or prevent it when applied in time. Even if you’re only just starting now, it’s still possible to boost your crop’s resilience and reduce the impact of heat and drought.

Ask yourself: What would it mean for your harvest (and for you!) if your crops could take the heat and keep performing?

How biostimulants build plant resilience

At Agro-Solutions, we work with biostimulants designed to be applied regularly from the beginning of the season. These products strengthen both plant and soil resilience over time, so by July, your crop is better equipped to cope with environmental stress.

Siliforce (silicic acid-based):

• Strengthens cell walls, helping reduce sunburn and dehydration.
• Improves water efficiency inside the plant. Silicic acid helps regulate transpiration, reducing water loss during stress conditions.
• Supports uptake of calcium and magnesium, both essential for fruit quality.

Moreover silicic acid accumulates in the outer cell layers of the plant, providing continued protection during later stress periods.

Example:
In pear orchards, Siliforce helps improve skin strength and reduces losses during sorting.
In potato crops, it supports tuber firmness and lowers the risk of softening during storage.

AMX (amino acid-based):

• Supports protein synthesis, even under high temperatures.
• Helps crops recover after stress by reactivating metabolic processes.
• Enhances the performance of fertilisers and crop protection products, even when uptake is limited.

Example:
In greenhouse vegetables like peppers and tomatoes, AMX is often applied as a foliar spray to support fruit set and relieve growth-related stress.

Micromix (microbial biostimulant):

• Activates beneficial soil microbes, even under hot and dry conditions.
• Improves nutrient availability in dry or less active soils.

Example:
In sandy soils or crops like onions and carrots, Micromix helps keep nutrients accessible when moisture or root activity is low.

What can you do this month?

The power of biostimulants lies not just in consistency, but also in timing. You want to build crop resilience before it’s needed. But if you haven’t worked with biostimulants yet, it’s still not too late. Even starting now can make a real difference in how your plants handle stress and help strengthen their resilience for the rest of the season.

Here’s what you can do:

• Make sure your applications are on schedule (repeat foliar treatments according to our advice).
• Keep a close eye on early stress symptoms like uneven growth, leaf-edge damage, or irregular fruit development. Acting quickly with a biostimulant at this stage can significantly reduce the impact.
• Check in with us or your advisor/distributor to see whether adjusting or intensifying your current application strategy could be beneficial.

Final thoughts

A well-prepared crop won’t be easily thrown off by a heatwave. July is when your early-season strategy is put to the test. Growers who’ve worked consistently with biostimulants are now seeing the results: stronger crops, steadier growth, and fewer signs of stress.

If you haven’t yet started using biostimulants in hot weather, now is the time to start. It can still make a real difference in how your crops cope with heat and drought. Explore our full range of biostimulants here.

Got any questions about (applying) Siliforce, AMX, or Micromix to your crops? Get in touch! We’re here to help.