As a result, trees usually respond best to fertilizer with a 2-1-1 or a 3-1-1 ratio (nitrogen-phosphorus-potassium). Commonly available fertilizers with a 2-1-1 or similar ratio are 18-6-12, 12-6-6, 10-6-4, 10-8-6 and 10-8-4.
For all trees and shrubs.
If needed, the best time to fertilize is late April or early May, or late fall once plants are dormant. The recommended fertilizer should be spread evenly across the soil surface. The amount of actual nitrogen applied should be 3 pounds per 1,000 square feet.
Many experts accepted this timing for years. And although early spring is a good time, new research indicates there is an even better time. Now a majority of arborists consider late September or October a great time to consider a fall fertilizer for trees and shrubs.
Fertilizing trees in the fall is important timing, particularly for deciduous trees, as many key nutrients are used up earlier in the year, producing leaves and fruit. To replenish those lost nutrients and prepare your trees for the next growing season, tree fertilization is key.
Other injuries to plants and trees are caused by over-fertilization: one is iron chlorosis. Plant roots exert force to extract water from the soil, and excessive fertilization causes roots to shrivel, making it difficult for them to absorb water. Root rot and roots being more susceptible to disease also occur.
Damage due to excessive fertilizer or rock salt applications generally appears as marginal leaf browning (brown edges or leaf tips) or leaf scorch on deciduous plants (they drop their leaves at the end of the season). On evergreen trees and shrubs needle tips will turn brown and become brittle.
Fertilizing in the fall helps plants be hardier when the temperatures drop. We also recommend applying fertilizer in the late fall, toward the end of October or early November. This application will catalyze one last frenzy of root growth and really give your plants some staying power through the cold months.
Nitrogen will help your trees grow throughout the winter and into the spring. It is the most commonly used fertilizer on trees, grass and other plants. Trees also often require either potassium or phosphorus as well to thrive.
If necessary, spring and fall are the best times to fertilize trees and shrubs. Fall applications should be made after leaf drop (mid-October through November). Spring applications should be made in late March or early April before the trees and shrubs begin to leaf out.
Young, rapidly growing trees should be fertilized annually to promote rapid establishment. Mature trees may need fertilization every two or three years to maintain good foliage color and vigor.
A complete fertilizer with a high ratio of both nitrogen and potassium is essential for enhanced rooting, cold hardiness, disease resistance, and wear tolerance. An ideal fall fertilizer blend has a nitrogen to phosphorus to potassium (N:P:K) ratio of 24-4-12 with isobutylidene diurea (IBDU).
Fall Fertilizer Timing
For the majority of cool-season lawn owners, apply fertilizer anywhere from September through early November. The further north you garden, the sooner you'll feed your lawn. Fine-tune the timing for your locale by talking with your local extension service or garden center.
Newly planted trees still in their development phase but after their first growing season needs to be consistently fertilized up to twice annually to help support their root establishment. Mature trees generally need lower amounts of nitrogen to keep their foliage and health in good condition.
Most importantly, tree fertilizer spikes inserted around a tree base leave your tree much more vulnerable to infestation from insects or tree diseases. These fertilizer spikes provide the perfect opportunity for insects to infest and damage the root system, which can lead to severe tree damage or even tree death.
Lawn fertilizers are not formulated for use on trees and shouldn't be used that way. In most cases, the fertilizer just won't do any good. In the worst-case scenario, "weed and feed" fertilizers can end up harming the tree.
Water helps "activate" your fertilizer. It helps move the granules deep into the thatch where it starts to break down so that it can be soaked into the root system. So rain after a fertilizer is a GOOD thing. The issues is when we get too much rain over a short period of time.
When To Fertilizer Your Lawn in the Fall. The best time to apply your last fertilizer application is between August 15 and October 1. Ideally, your last lawn feeding should take place six to eight weeks before the average first frost in your area.
While the best method for determining exactly how much fertilizer is needed is a soil analysis conducted by a laboratory, most cool-season grasses require 2 to 4 pounds of nitrogen per 1,000 square feet each year, and a majority of this nitrogen should be applied in two fall applications; one in September and the other ...
A “complete” fertilizer — one that supplies the macronutrients nitrogen (N), phosphorus (P), and potassium (K) — is often recommended. A fertilizer analysis of 10-8-15 means the fertilizer has 10 percent nitrogen, 8 percent phosphorous, and 15 percent potassium.
Fertilizers can quickly save your trees from dying. However, not applying them properly will damage your trees more.
Rates of fertilizer application are typically based upon the amount of nitrogen in the fertilizer since nitrogen is the mineral element most responsible for vegetative growth. For annual maintenance, it is recommended that a tree receive 1 to 3 pounds of actual N per 1000 sq. ft.
You can safely apply up to 1 pound of nitrogen per 1,000 square feet per year. A 20-pound bag of 10-10-10 fertilizer, enough to cover 2,000 square feet, contains 10 percent or 2 pounds each of nitrogen, phosphorus, and potassium.