JoAnne Skelly: Knowing the ins and outs of summer fertilizing

In the ideal horticulture world, a healthy soil provides all the nutrients that plants need to grow. Unfortunately, Nevada rarely has soils that optimize plant growth because they contain little organic matter and few nutrients. These soils challenge the gardener trying to keep plants healthy. We must build up our soils to supply plants’ nutritional needs.

In order to improve a soil, we have to feed the soil, rather than focusing on feeding the plant. Adding organic matter in the form of well-decomposed compost helps produce hardier, disease and insect resistant plants. Proper fertilizing in summer is important and can increase vegetable yield and flower production. Improper fertilization encourages lawn diseases, burns plants and may cause rampant green growth of vegetables with little fruit set.

Fertilizers can be organic or inorganic. Organic fertilizers are less likely to burn plants than inorganic products. Inorganic fertilizers are readily available. Inorganics come in a wide range of nutrient ratios, such as 16-16-16, 5-10-10 or 21-0-0, to name a few. Whether a fertilizer is organic or inorganic is not important to how the chemistry of a plant functions. However, organic fertilizers can increase soil microorganisms, which improves soil fertility, water-holding capacity and nutrient exchange. Inorganic fertilizers do not.

Now that it is hot, the only fertilizer that should be applied to a lawn is a slow-release or an organic product. A typical lawn fertilizer is too high in nitrogen (N) for summer use. These products will most likely burn the grass at this time of year. They also encourage a lot of tender young growth that is easily stressed and damaged in the heat. Stressed plants, including grass plants, are susceptible to diseases.

Roses are regular feeders and need light fertilization every two to three weeks. Apply an inorganic rose fertilizer in one application and alternate with an organic fertilizer such as compost tea or liquid kelp. Vegetables do well with an application of one tablespoon of a 5-10-10 per plant every three to four weeks. Of course, adding a generous helping of well-decomposed compost around each plant is always an excellent practice.

No matter what fertilizer you use, or what plant you are fertilizing, make sure the plant is well-hydrated prior to application. Then, immediately after fertilizing, water thoroughly to wash excess product off the plants and into the soil. Fertilizer and irrigate when the sun goes down to avoid burning plants.

JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at


Use the comment form below to begin a discussion about this content.

Sign in to comment