The Type Of Fertilizer You Should Avoid Using In High Heat At All Costs

During extreme summers, it is a common fallacy on the part of novice but enthusiastic gardeners to think that applying a little fertilizer can revive a plant suffering from the symptoms of heat stress. And although you do need to attend to the wilting and curling of leaves caused by the heat, immediately showering your plants with nutrients is a bad idea, especially if it is coming from a typical synthetic, quick-release fertilizer. A flush of nutrients in the soil can force the plant to grow new foliage in a stressed environment, where all it is looking to do is conserve moisture and energy. This can result in long-term damage for the plant — it may dry out, get infected with diseases, or suffer from fertilizer burn. If you think your plants need a nutrient boost, nonetheless, you can either use a slow-release fertilizer or a completely organic one. 

It is easy to spot telltale signs of fertilizer burn during summers, in both lawns and indoor container plants, by identifying some common symptoms. For instance, if you begin to see a brown or white crust getting collected either along the inside rim of the container or in the potting medium itself, your plant is probably getting over-fertilized and the heat is making it worse. In lawns, this may be seen as dead turf, brown patches, or a pattern of stripes where excessive salt from fertilizer has accumulated.

Many synthetic fertilizers are heavy in nitrogen. In high heat, the overload of nitrogen causes unsustainable growth and stress to the plant. Also, the excessive salt from fast-release fertilizers can get concentrated in the soil and damage plant roots during summer. Some soluble salts also find a way to travel through the roots and get concentrated in the leaves. Both of these states are extremely damaging as they can result in conditions such as wilting, stunting, marginal yellowing, or complete leaf scorch.

Since the heat is at its peak during the summer, transpiration (the loss of moisture through evaporation from the leaves) is at its highest, and the plant requires more water than ever. This makes it all the more difficult for the leaves and the plant to endure the high salt concentration levels in the soil as compared to, say, a cloudy spring day. Leaf burn can also result from the fertilizer coming in direct contact with the leaves, especially if it is applied in a granular or liquid form. 

Although extreme heat is one of the major signs from the weather you shouldn't fertilize your lawns or garden at all, the next best option is using a slow-release formulation. You can also use an organic fertilizer (such as alfalfa meal) that will do wonders for your garden. These fertilizers do not damage plant roots since they slowly trickle their nutrients into the soil, constrained by the action of microorganisms to be nutritionally available for the plants. Organic fertilizers are also far more balanced in their composition, in terms of the ratio of nitrogen, phosphorus, and potassium minerals, and will not overwhelm the plant with excessive nitrogen supply during stressful summer days. 

Organic fertilizers, besides being easy on the plants during summers, are also great for the soil in several ways. They add organic matter to the soil and boost its ability to hold water and minerals. They also enhance soil health by boosting microbial action. They do not get leached in the soil easily, unlike their synthetic counterparts, and don't need constant reapplication either. Apart from the macronutrients, organic fertilizers will also provide a constant supply of micronutrients to the plants. Having said that, you still need to follow the instructions on the fertilizer package, avoid overapplying the fertilizer (even if it is organic), and take the nutrient composition of the soil and the state of your plants into account before you go forward.