Some people may feel uncomfortable with the practice of garden fertilization. The idea of applying fertilizer as part of a lawn and garden maintenance program causes concern about potential negative effects over time. This is a valid concern but not so much a cause for worry. It’s true that using the wrong type of fertilizer or applying it improperly could produce negative effects. However, since most materials are now regulated, it would be difficult to purchase harmful materials and unusual for a certified landscape professional to make that sort of a mistake.
Lawn & Garden Fertilization — Necessary or Not?
Although garden care practices that improve soil health tend to take up the greater portion of any garden management program, garden fertilization is necessary component and the main reason is nitrogen. Nitrogen is the most important nutrient plants use for food production, and it does not linger in soil as other nutrients do. In a “curated” environment like the landscaping around your home, fertilizer must be reapplied periodically. Why? Out in the woods and fields, nature makes its own fertilizer from fallen branches, leaves, and other decomposing materials.
Our desire to maintain a tidy appearance around our homes has us removing organic matter every fall and spring with branch and leaf removal. The naturally occurring fertilizer that resupplies nitrogen and other nutrients to the soil can’t be created in the cultivated setting. So we have to apply it manually/artificially from time to time.
The nitrogen contained in most fertilizer blends plays a critical role in photosynthesis, the process by which plants make food. If soil nitrogen levels are too low the plant cannot make enough food to remain healthy. Just like people, plants that are malnourished will decline over time. They won’t grow normally or produce flowers as they would.
While other nutrients tend to stay fixed in soil, nitrogen behaves differently. It moves around a lot. This is the reason a soil test never tests for nitrogen. It varies too much. While nitrogen comes and goes, other nutrients are always present at various levels . Testing shows where you need to add and where you have enough.
The Horticulturally Correct Approach to GardenFertilization
Your landscape maintenance professional will follow horticulturally correct procedures as to the type and amount of fertilizer that will be applied to your lawn and different types of plants. They will perform garden fertilization tasks on regularly scheduled visits throughout the growing season.
Lawn fertilization
Lawn maintenance is in a category of its own. We usually split lawn applications into four treatments. Because nitrogen moves around so much, we don’t want to drop it all at one time because it may leach away before plants can use it. For cool season grasses we fertilize in early spring (March), late spring (May), late summer/early fall during cool temperatures. There is a final application in late fall (November) to supply nutrients throughout the winter. We use a slow release material for this 4th application because the roots continue to grow and use nutrients during winter.
Trees & shrubs
A typical garden fertilization program will focus on smaller trees because the roots of large mature trees reach out so far they can grab nutrients from a wide area around them including from the lawn. For smaller trees and shrubs we fertilize early in spring when they start growing. We want to have nutrients readily available to them at that time. We may do a second application in late summer/early fall when plants are busy making food to store in the roots over winter. It is beneficial to give them a little boost of nutrients at that time.
Flowering Plants
The garden fertilization schedule for herbaceous flowering plants is approximately every six weeks or so in spring, mid summer and late summer. We use a granular time release material because plants use a lot of nutrients during the growing season.
Summer annuals in beds or containers get the same treatment as herbaceous flowering plants: spring, mid summer, and late summer at approximately six week intervals.
Fall Annuals
Garden fertilization for flowering fall annuals takes place at installation time in October and again in mid-March when they begin growing again. The spring treatment will keep fall annuals going until May–around the time when we would swap them out for summer annuals.
Unlock the full potential of your lawn and gardens!
What’s the difference between a conventional landscape company and one whose staff understands design, horticulture, and landscape systems? To find out, click the button below.
Non-flowering fall annuals such as ornamental cabbages and kale will usually stay looking good through the winter and start to bolt in spring when they reach the end of their life cycle. When a plant “bolts” it shoots up stalks that display an inflorescence of flowers and seed. Some people don’t care for the look of plants that have bolted and will replace them in the spring annual rotation. Others choose to leave them because they attract butterflies and provide food for butterfly larvae.
Types of Garden Fertilizers – What Are the Options?
There are two primary types of garden fertilizers. They come in a variety of different formulas to meet different plant needs at different times of year.
Liquid Fertilizers
We would only use liquid fertilizer to make a quick correction. For example, if we were late with the spring application, we would use it to treat plants that are showing signs of malnourishment. The liquid material is absorbed quickly and delivers a potent shot in the arm to bring the plant back. It doesn’t have the long lasting effect of the time release material
Granular Fertilizers
These come in different formulations depending on the use. Most last four to six weeks on the ground. That’s why we split spring applications between March and May–to meet the needs of the plant at particular times in the year.
Lawns are a good example on this point: In spring lawns get a formula that is high in nitrogen and low in phosphorus and potassium. The formula changes in late summer/early fall. At that time the mix will have a moderate nitrogen level and higher phosphorus because phosphorus aids in seed germination and root development. You want that specifically for young grass that you planted the previous fall.
We try to put down only what the grass can uptake during a prescribed time period to prevent leaching of nitrogen through the soil. And as far as negative effects go, too much phosphorus is the bigger concern for protecting our waterways. We tend to use as little as possible or none unless we are spreading fresh seed.
Corn Gluten
Corn gluten is a fully organic material that supplies a lot of nitrogen for spring applications to speed up growth.
Fertilizer Pellets
Pelletized fertilizer made of compost and manure usually comes as a slow release material made of fully organic material. It can be used effectively in spring or fall to deliver a slow, steady feed of nutrients to your lawn or garden plants.
Compost Top Dressing
Compost top dressing is applied in the fall because it will break down over winter and the following season releasing nutrients slowly. Top dressing supplies the main source of nutrients in the fall.
Overall, garden fertilization is beneficial for lawns and landscape plants when choice of materials closely matches the size of the plant, in the correct amount, and is timed to its specific needs during the season. As long as fertilizer is used in a horticulturally correct manner, it provides an enormous benefit to landscape plants, trees, and lawns.
Perhaps you’ve been wondering how to bring out the fullest expression in your landscape and gardens. Our eBook: Choosing the Right Kind of Landscape Maintenance Firm, is full of valuable information to help you understand the fundamental differences between landscape maintenance companies.