Applying Fertilizer During High Temperatures May Negatively Impact Plant Growth
In the warmer months, it's essential to take extra care when fertilizing plants to avoid overfertilization and heat stress. Here are some best practices to follow, as suggested by Susan Albert, a former master gardener and prolific garden writer.
Use slow-release or organic fertilizers, such as slow-release granular fertilizers, fish emulsion, compost, compost tea, worm castings, cottonseed meal, blood meal, or alfalfa meal. These are safer in hot weather and reduce the risk of fertilizer burn.
Apply fertilizer during the coolest parts of the day, preferably early morning or evening, to minimize plant stress and nutrient damage from heat. It's also recommended to avoid fertilizing during extreme heat waves or if plants are drought-stressed; wait for cooler temperatures and ensure plants are well-watered before fertilizing.
Side-dress fertilizer by placing it around the plant perimeter or in bands next to rows, rather than applying it directly onto plant foliage or stems. This protects plants from fertilizer burn and ensures better nutrient uptake.
Water plants before and immediately after fertilizing to dissolve nutrients and help their absorption at the roots. If possible, time fertilization before rain to reduce root damage.
Use reduced quantities of fertilizer in summer, for example, applying half the recommended label rate, to prevent overfertilization and nutrient buildup, especially in late summer when some plants reduce nutrient uptake.
Mid to late summer are typically too hot to fertilize the lawn. Granular fertilizer should not touch the leaves. Avoiding overhead irrigation and wetting the leaves can prevent fungal diseases. Brown or dead patches of grass in lawns where the spreader over-compensated are symptoms of overfertilization. A soaker hose or drip irrigation works best for watering plants.
Erecting a shade cloth can provide afternoon shade for plants if none is available. Mulching can stabilize the soil temperature, retain moisture, and enrich the soil. Cool season annuals, such as pansies, usually don't survive when the temperature soars. Cool season vegetables, such as broccoli, will bolt when it turns hot.
Applying fertilizer in summer should be done lightly or when the plant shows signs of low fertility. Row covers can help screen vegetables. Overfertilization results in excess salts near the roots of plants, which can damage them and restrict the flow of water. Salt can affect plant tissues, causing dieback or brown edges on leaves.
Heat can cause premature blossom drop in cucumbers, melons, tomatoes, peppers, squash, and beans. Brown or whitish crust at the top of the soil or sides of a container plant is a symptom of overfertilization.
In summary, to avoid overfertilization and heat stress during summer, use gentle, well-timed, moderate fertilizing combined with proper watering, soil care, and protective measures like mulching and shading.
Liz Baessler, the Senior Editor, emphasizes the importance of these practices to ensure the health and vitality of your garden during the summer months.
Maintaining a health-and-wellness approach for your garden, consider implementing practices suggested by Susan Albert, such as using slow-release or organic fertilizers for fitness-and-exercise, providing adequate water, and ensuring proper soil care to reduce stress on plants. Consulting Liz Baessler's guidance, it's essential to remember that timely and moderate fertilization, combined with good watering and protective measures, contribute to overall nutrition and health of your garden in summer.
