Whether you grow organically, conventionally or
whatever-you-have-available-ly, making sure your plants have enough nutrients
is an important part of good gardening. If your soil already has a normal pH, a
healthy amount of organic material and available nutrients you may be fine, but
if it doesn’t you may need to add additional fertilizer and nutrients to your
plants. (If unsure you can check the mineral composition by having your soil
tested through a soil testing facility near you). Whether you choose to improve
soil nutrients by compost, green manure, or synthetic fertilizers, the choice
is up to you.
Knowing what is in your fertilizer, and what your plants
need is the first step in proper fertilization. Plants require both macro and
micronutrients, and the composition and amount of these nutrients change
depending on what growth stage your plants are at. The three macro elements plants
require are Nitrogen (N), Phosphorous (P) and Potassium (K). Micronutrients and
the amount needed, vary for particular plants, but boron, manganese, sulfur and
calcium are all common ones. While these may not be as well known as the
macronutrients, they too play an important role in your plant’s health. Even if
macronutrients are abundant, plants can only be as successful as the least
available nutrient.
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| Peas happily growing in the garden. These likely don't need fertilizer. |
Commercial fertilizers typically have three numbers (i.e.
20-10-5). The first number refers to the nitrogen content, the second to your
phosphorous and the third to the amount of potassium. You can buy complete
fertilizers (with some combination of all three nutrients) or you can buy
single element fertilizers (pure phosphorous fertilizer would be 0-10-0). Nitrogen is a major component of your
garden plants and is essential for plant growth. In many fertilizers it is
going to be the bulk of the nutrients. Using a granular application of nitrogen
before planting can supply sufficient nitrogen for the entire growing season.
Nitrogen will boost your foliage growth, increasing plant size and
photosynthesis. Nitrogen sounds amazing for your plants, right? Well too much
of a good thing can also be a problem. Too much nitrogen can leach through the
soil and contaminate ground water and it can reduce flowering, which will decrease
your yields in many instances.
Phosphorous (the second number) is important for energy
production, protein synthesis and plant growth. Potassium (the third number) is
important for many plant processes including response to drought, insects. Early during the growing season when the soil is
cooler, it is more difficult for plants to take up phosphorous (and potassium).
As the weather warms, these minerals will become more available and fertilization
may not be necessary (depending on your natural soil levels).
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| For best yields, cucumbers need additional nutrients |
In general, you should apply fertilizer early in the growing
season to promote vigorous plant growth, applying a fresh mixture almost
monthly Remember, fertilizing won’t improve your soil’s structure, microbial
community, or drainage, but if properly implemented can improve your plants’
health and yields. So even though rain may be abundant, don’t forget to add a
to add some extra nutrients to your plants. They’ll love you for it.
Sources consulted:
Utah State University Bulletin on successful fertilizing:
From the Missouri Master Gardener’s manual: http://extension.missouri.edu/p/MG4
Oregon State University manual:
Penn State Guide on Fertilizers:
Wang M., Zheng O., Shen O., Guo S. The critical role of
potassium in plant stress response. 2013. Int. J. Mol. Sci. 14(4) 7370-7390.
