The Best Fertilizer for Ornamental Grasses: A Complete Guide

Most established ornamental plants in the landscape require care to stay healthy and attractive. Regular fertilization, pruning, watering, mulching and pest control are all part of a good landscape management program.

Some plants, such as annual flowers, roses, red-tip photinia and English laurel, are more demanding than others. Annual flowers and roses must be kept well-supplied with nutrients and water at all times, pruned and groomed routinely, and monitored regularly for pests if they are to flower abundantly. Red-tip photinia and English laurel are very susceptible to leaf spot diseases and demand more care.

On the other hand, plants such as ornamental grasses, hollies and junipers, when properly planted on a good site, require little care once established and are considered good low-maintenance plants.

Caring for ornamental plants is more difficult when they are not well-suited to the site selected or when they are improperly planted. Azaleas, for instance, prefer a moist, well-drained soil and shade from the mid-afternoon sun. When planted in poorly drained soil or in full sun without the benefit of irrigation, azaleas become stressed, susceptible to attack from insects and diseases, and require more care. Planting too deeply or too shallowly also causes plant problems.

Today, the concept of low-maintenance landscapes is more popular than ever before. The idea of putting less effort into the landscape without sacrificing quality and beauty is very appealing to a growing number of homeowners and clients of landscape professionals. By applying lower amounts of fertilizer, water and pesticides to the landscape, you not only help the environment but also save time and money. New concepts in low-maintenance landscaping, such as Xeriscaping (water-efficient landscaping) and integrated pest management (control of pests through the selective use of insecticides and encouragement of natural enemies), are proving that it is possible to have a beautiful landscape while saving time, effort and money.

This publication provides guidelines for the care of established ornamental plants in the landscape. Low-maintenance alternatives to traditional cultural practices are discussed throughout the publication.

Start by identifying areas of the landscape that require different amounts of care. A recently planted area, for instance, will generally require more attention than a well-established area. The highly visible public area of the landscape is usually an are where optimum growth is desired at all times, while a secluded, private area requires less maintenance. Once this “zoning” is done and the different levels of plant care are established, landscape maintenance becomes much more efficient and effective.

Fertilization is an important part of landscape maintenance, particularly in urban areas where much of the native topsoil is removed during development and subsoil deficient in essential nutrients becomes the new topsoil.

Unfortunately, fertilization is a rather simple cultural practice made complex and confusing by the wide variety of fertilizer products on the market today — from “general-purpose” garden fertilizer to specialty products, such as pre-mixed liquid fertilizer concentrates, water-soluble crystals, slow-release fertilizers, azalea/camellia fertilizers and rose specials. Plants generally do not care whether a fertilizer is granulated, liquified, encapsulated, briquetted, pelletized or solubilized! They simply want nutrients in any form they can use.

Fertilizers, however, differ in nutrient content and release duration. The type of fertilizer you select should be based not only on its cost but also on the types of plants being fertilized, the existing nutrient content of the soil, and the type of growth response desired. Liquid or water-soluble fertilizers, for instance, are often used on annuals and herbaceous perennials immediately after transplanting because their nutrients can be absorbed quickly and used by the plant. Woody ornamentals, on the other hand, store food reserves in their roots and do not have an immediate demand for nutrients after transplanting as short-season annuals do. They benefit from slow-release fertilizers that ensure a supply of nutrients as needed.

To determine whether a granular fertilizer has slow-release properties, look at the analysis on the back of the bag. Nitrogen listed in the form of ammoniacal nitrogen indicates that the product has some slow-release property. If the nitrogen is listed as being derived from urea, urea-formaldehyde, IBDU (isobutylenediurea), or sulfur-coated urea, the release duration of the product will be increased. Some granular slow-release fertilizers last six to eight months after application.

Other commonly available slow-release fertilizers on the market include Osmocote granules, Osmocote tablets, Jobes Spikes, Once, Woodace briquettes, Agriform tablets and Milorganite. These fertilizers generally cost more per pound than general-purpose granular fertilizers such as 10-10-10 or 12-4-8, but they also last longer and dont need to be applied as frequently.

Organic fertilizer sources such as bone meal, cottonseed meal and animal manures can also be used. Table 1 lists the average nutrient content of several organic fertilizer sources. Compost is another good source of slowly available nutrients.

When Should You Fertilize?

Research shows that woody plants actively absorb nutrients from the soil during the growing season and require few nutrients during the dormant winter season (see Figure 1). Therefore, apply fertilizer as soon as the plants begin breaking dormancy in the spring, and avoid fertilizing after the first fall frost, which signals plants to begin resting for the winter.

Which Analysis Is Best?

A soil test, available through your county Extension office, is the best way to determine which fertilizer analysis is best for your soil. As a general guideline, most ornamental plants will benefit from a fertilizer having its primary nutrients (nitrogen, phosphorus and potassium [N-P-K]) in a 3-1-2 or 4-1-2 ratio. A 12-4-8 fertilizer, for instance, is a 3-1-2 ratio, and a 16-4-8 fertilizer is a 4-1-2 ratio. Research shows that phosphorus, the middle number in the analysis, is held be soils and does not leach with rains or irrigation as nitrogen or potassium do; so it is usually needed in lower amounts. On new sites where phosphorus has never been applied, a complete balanced fertilizer such as 8-8-8 or 10-10-10 is sometimes recommended.

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FAQ

What fertilizer do you use for ornamental grasses?

For the best care, fertilize sparely in the spring with a slow-release fertilizer such as 3-1-2 or 4-1-2 ratio.

What is the best food for ornamental grasses?

Multi Purpose 10-10-10 Fertilizer works well. Using liquid fertilizer ( Miracle Gro 20-20-20) is done the same way as watering, but with fertilizer mixed in. It should be done 3 or 4 times per year starting in late April and stopping in mid July. Organic fertilizers, like manure, can also be used with good results.

Can you put Miracle Grow on ornamental grass?

A month after planting, give your new ornamental grasses a nutritious meal of Miracle-Gro® Shake ‘n Feed® All Purpose Plant Food to keep them growing strong.

How do you keep ornamental grasses looking good?

Ornamental grass is drought-resistant, so you don’t have to water it much, and most pests don’t find it appetizing. You only have to cut them back occasionally to eliminate the brown grass and keep it from dying. Additionally, you will have to divide it every few years.

What is the best fertilizer for ornamental grasses?

Organic fertilizers are gentle and easy for plant roots to uptake, as well as healthy for the entire garden. When choosing what to feed ornamental grasses, try organic soil amendments such as compost, leaf mold, mushroom manure, and other easily broken-down organic substances. You may also choose to use a basic 10-10-10 balanced food.

What is the best fertilizer for fountain grass?

Excess food can also cause an unstable plant with limp blades. In the first year, fountain grass can benefit from some organic fertilizer applied at planting time. Alternatively, the best fertilizer for fountain grass is a time release fertilizer that will last through summer and help the plant build a vigorous root system and initial form.

Does fertilizer help ornamental grass grow?

Still, a little fertilizer can help an ornamental grass flourish, especially if a mature plant is a few years old and the soil lacks fertility. This is common when growing the grasses in containers, since the nutrients present in the original potting mix fade with time.

How do you fertilize ornamental grass?

If you want to fertilize ornamental grass, use a balanced, slow-release fertilizer like Osmocote 14-14-14. You can avoid fertilizers designed to encourage flowering. Ornamental grasses need little fertilizing. Avoid fertilizing in fall, winter, or on hot summer days. Apply fertilizer in spring when new growth appears.

How much fertilizer should I put on ornamental grass?

If your grasses take on a faded color and look less than vigorous, a small amount of fertilizer will perk them up. When fertilizing ornamental grasses, remember that less is more; err on the sparse side when feeding the plants. A general rule of thumb is to apply ¼ cup (59 ml.) per plant in the spring as growth starts back up.

Should ornamental grass be fertilized?

Fertilizing ornamental grasses with the same food you use on the lawn might seem logical, but think about what happens when the lawn gets fertilized. The grass grows very rapidly. If ornamental grasses go on a sudden growth spurt, they tend to flop over, losing their aesthetic value.