Fertilizing is an important part of lawn and landscape maintenance, but applying fertilizer at the wrong time can do more damage to a plant than leaving it alone.
When to fertilize depends on your climate, soil, plant, and variety. In general, established plants should be fertilized in the spring and/or fall, while seedlings, annuals, and container plants may need consistent applications throughout the growing season.
Ready to fertilize?
Not so fast.
First, let’s go over a few basics:
- Annual compost applications are sufficient for most established plants.
- Slow-release fertilizers promote healthy, sustainable growth, while quick-release fertilizers can burn roots.
- Under-fertilizing is always better than over-fertilizing.
- Fertilizer is not medicine for sick plants; check for pests, diseases, drought stress, overwatering, and other problems before you use fertilizer.
- Our recommendations are for general-purpose fertilizers. Nutrient-specific amendments, like chelated iron, can be applied whenever you have a confirmed deficiency.
- Nutrient imbalance can be caused by soils that are too acidic or alkaline for the plant. Do a pH test to make sure your plants are able to use the existing nutrients in the soil.
Now, let’s get started.
Best Time to Fertilize: Lawns
Turfgrasses are split into two major categories: cool-season grasses and warm-season grasses.
Cool-season grasses grow more in the spring and fall, and may go dormant during hot, dry summers.
Warm-season grasses break dormancy later, and grow more during the summer.
Fertilize cool-season grasses late in the summer to early fall. This gives the lawn nutrients to recover from summer stress, as well as helping the roots prepare to store energy for the winter.
Fertilize warm-season grasses once in the spring after the first few mowing sessions, and again six to eight weeks before the first frost in the fall. This gives the lawn a boost when it breaks dormancy, and helps the roots prepare for winter dormancy.
For more tips on maintaining a lush, green lawn, see 7 Ways to Make Your Grass Greener.
Best Time to Fertilize: Established Trees & Landscapes
Newly-transplanted and established trees rarely need fertilizer. Most trees will have sufficient fertilizer from lawn applications, and the extensive root systems allow trees to access nutrients deep below the surface.
Newly-transplanted trees and shrubs should not be fertilized, because nitrogen will force them to grow new leaves when it should be focused on repairing the root system. Instead, add a few handfuls of compost into the ground when you transplant.
Established trees and shrubs should only be fertilized in early spring when soil tests indicate a deficiency. Annual compost applications are more beneficial to the plant and will help maintain adequate nutrient levels.
Best Time to Fertilize: Fruit Trees
Fruit trees have a burst of new branches, leaves, and flowers in the spring, followed by weeks or months of fruit development.
The ideal time to fertilize fruit trees is in early to mid-spring before bud break. This gives trees a burst of energy for green growth and blooming.
Keep in mind, established fruit trees may not need fertilizer.
Best Time to Fertilize: Vegetables
Most vegetables are annuals, so you don’t have to time your fertilizer applications to coincide with dormancy.
Instead, vegetables should be fertilized according to their overall health, with more or less time between applications depending on the soil quality.
Fertilize vegetables in sandy soil at the beginning of the season and every 3-4 weeks throughout the growing season if the plants begin to lose color or vigor. If plants are lush and green, avoid fertilizing or you may burn the roots.
Fertilize vegetables in clay soil at the beginning of the season and every 4-6 weeks throughout the growing season if the plants begin to lose color or vigor. Clay soils may also cause root rot, so make sure you are irrigating correctly before you try to correct growth problems with fertilizer.
Best Time to Fertilize: Annuals
Annuals are meant to bring a temporary pop of color to an established landscape or flower bed.
Fertilize annuals at the beginning of the season before planting, and every 6-8 weeks during the growing season as needed. Annuals are meant to be showy and colorful, so it’s important to fertilize if the plants begin to show signs of nitrogen deficiency, like yellow (chlorotic) leaves.
Best Time to Fertilize: Container Plants
Container plants are permanently restricted to a planter, container, or pot. These plants are watered more frequently than in-ground plants, which leaches nutrients out of the potting mix.
Fertilize container plants every 2-8 weeks, depending on the species and time of year. Flowering and fruiting plants will need consistent fertilization to support blooms and fruit set, while vegetative plants may be able to go 3-4 months without fertilization.
Even plants with a slow-release fertilizer in the soil mix will eventually require fertilization. Research your plant’s nutrient requirements and fertilize accordingly.
Best Time to Fertilize: Seedlings
Seedlings are in temporary containers while they grow large enough for transplant. In order to prevent damping off and other pathogens that attack seedlings, most seed-starting mixes are sterile, which means they have no nutritional value for the plants.
Fertilize seedlings once they have one set of true leaves. This is when the plant has used up the nutrients from the endosperm within the seed, and when the roots will start looking for nutrients in the soil. Seedlings grow very quickly, so it is important to start fertilizing as soon as the first pair of seedling leaves emerge in order to keep up with this growth.
For truly stunning landscapes, you need a reliable irrigation schedule, mowing schedule, and maintenance schedule. Hidden Creek Landscaping INC. provides professional landscape services for commercial and residential areas. Contact us today for more information.