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How & When to Fertilize Flowering Landscape Plants

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Nothing can transform your ho-hum landscaping into a spectacular display like the addition of flowering plants. Caring for them so they flower, whether trees, shrubs or plants, depends more on what fertilizer you use and when you apply it than almost anything else.


Take a sampling of your soil to your local cooperative extension--a department that works with a state university to assist citizens with agricultural matters--to have it tested. Having your soil tested will tell you what nutrients you must add, if any, for successful gardening.

Select a fertilizer for your flowering landscape plants that is lower in nitrogen, higher in phosphate and lower in potash, such as a 5-10-5 blend. Higher nitrogen will promote foliage growth at the expense of flowers. A higher phosphate level aids your plants in producing flower buds.

Choose either a time release, dry formula fertilizer or a liquid fertilizer. The timed-release fertilizer will save you time and effort because you will not need to reapply it as often. A liquid fertilizer will give you more immediate results because it is absorbed into the foliage and soil directly, but you will need to reapply it more often.


Apply your 5-10-5 formulated fertilizer in the late fall and again in the early spring to your flowering landscape plants.

Reapply 5-10-5 fertilizer every two to three weeks if your soil is sandy, of poor organic quality or you are using a liquid type fertilizer. The inexpensive soil test will tell you the quality of your soil and how often you may need to supplement it with fertilizer for best growing results.

Stop all fertilizing of your flowering plants when you see the buds of blossoms begin to develop. Additional fertilization at this point will cause your flowering plants to produce fewer blossoms.

Apply one final application of fertilizer to your flowering landscape plants after the plant has finished blooming, usually in the late fall.


Use one pound--roughly 2 1/2 cups--of 5-10-5 blend fertilizer for every 100 square feet of landscape plants.

Apply the pellets by broadcasting, either by hand or with a fertilizer spreader, over the root system of trees, shrubs and woody landscape plants.

Water the fertilized area immediately after broadcasting the pellets. By applying water directly after fertilizing, you are starting the process of the fertilizer breaking down and entering the soil to benefit your flowering plants.


There are some flowering landscape plants--for example, azaleas--that require a specialty formulated fertilizer to promote flowering. It is always advisable to confer with your local garden nursery personnel or cooperative extension office concerning the care of various plants in your landscaping.

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