The Lowdown on Fall Fertilizing

cooler temperatures and shorter days send signals to plants to slow down on the above ground growth, so you need to feed the roots.

Earth Juice® Grow™ 2-1-1 16 oz. concentrate
Item # 99746 		Earth Juice® Grow™ 2-1-1 Organic Liquid Fertilizer

each $12.99
Liquid Gro-Power 4-8-2 - 32 oz. bottle
Item # 99711 		Liquid Gro-Power 4-8-2

each $9.95
  • Topic: Fall Gardening
  • Author: Cindy Bellinger
  • Keywords: fall fertilizing, fall, roots, Fall Gardening, gardens
  • Date: September 2003

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Think of it this way. Feeding plants in the fall is like giving lots of acorns to bears. For both, it’s a sure way to get them through the winter.

Once leaves and flowers begin to die back, it looks like all plant activity has finished. But cooler temperatures and shorter days finally send signals to plants to slow down on the above ground growth and concentrate on what’s underground. With an inordinate amount of activity taking place in the roots, fall is the opportune time to fertilize.

According to Dirk Muntean, a biologist with Soil and Plant Laboratory, Inc. in Bellevue, WA: “Roots take up nutrients in the soil throughout the fall until the soil temperatures drop low enough to inhibit root function.”

But with so many fertilizers on the market it’s hard to know what to use. What you need to look for are the three hyphenated numbers on fertilizer products. These indicate the ratio of nitrogen, phosphorus and potassium. It’s a formula of percentage often referred to as the NPK.

N = nitrogen, P = phosphorus, K = potassium (usually listed as potash).

In the fall plants have different needs, so fertilizers low in nitrogen are preferred. Nitrogen stimulates green above ground growth. What you want now is a fertilizer richer in phosphorus and potassium because it’s these nutrients that feed the root system.

Take Gro-Power Flower and Bloom, for example. It has a 3-12-12 ratio, which means nitrogen is 3 percent of the nutrients, the phosphorus and potassium are both 12 percent. It’s a good fall fertilizer.

Fertilizers with the higher number first (nitrogen) are great for spring fertilizing, but not for fall. A quick search in our Garden Center turned up a range of ratios on various bags and boxes of fertilizers. Following is what I found:

9 - 58 - 8
14 - 6 - 4
15 - 30 - 15
2 - 7 - 7
23 - 18 - 16
3 - 20 - 20
4 - 4 - 2

The fertilizers we recommend for fall are Yum Yum Mix® and Earth Juice. Both are low in nitrogen.

If pants have developed chlorotic (yellow) tips on their foliage over the summer, they are showing signs of diminished iron. Fertilize now with Greensand. Aspen, Purple Leaf Plums, Peaches and Wisteria commonly exhibit chlorosis. Greensand is an all-natural iron source that helps “green-up” the plants next summer.

The best time to fertilize in the fall is after a few light frosts or when the trees begin dropping their leaves. Fall fertilization will also promote recovery of root systems damaged by drought. This is especially important for drought stressed pinon.

Though it sounds odd to feed plants when they are shedding their leaves, it really is like getting a bear ready to hibernate. Well fed, they’ll get through the winter just fine.