Is Feeding Frenzy Really Needed?
Written by UC Master Gardener Dan Vierria
Before reaching for fertilizer,
ponder this: the runoff that eventually swirls down storm drains pollutes our
waterways. Aquatic life and the quality of drinking water can be affected. Those
who wonder if plants need nitrogen, phosphorous or potassium (The Big Three of
fertilizers) might also ask “Do I need fertilizer at all?”
Determine plant needs
Fertilizers often are
regarded as the cure-all for ailing plants, browning lawns and struggling trees.
More often than not, lack of essential nutrients is not the problem. Too much
water, the same abundant use of water that washes excess fertilizer down storm
drains, may be the likely suspect. Moisture imbalances in soil, either too much
or too little water, are the No. 1 environmental factor that impacts plant
health. It’s always a good idea to inspect irrigation systems for clogged
emitters and spray heads, broken pipes, errant spray patterns and incorrect
Other symptoms of nutrient deficiencies could be caused by
unhealthy roots, poor soil conditions, or improper care.
soils contain most of the elements essential for plant health. In the Sacramento
area, soils may be deficient in nitrogen. A soil test can determine if nitrogen
is needed. Inexpensive soil-testing kits can be purchased at nurseries and more
detailed testing can be submitted to soil-testing labs.
Consider replacing lawn
Lawns demand more
frequent irrigation and nitrogen use than shrubs and trees. Consider replacing
or reducing large turf areas with plants that require less fertilizer and water. Buffalograss and zoysiagrass are among alternative turf choices that require
about half as much nitrogen as traditional turf choices. A
mulching mower that
returns grass clippings to your lawn can provide as much as 20 percent of a
lawn’s fertilizer needs.
Several woody ornamentals, like nonflowering trees and
shrubs, don’t need fertilizer, even at planting. Plants that are most-often
thirsty for fertilizer feedings are flowering shrubs, some annuals and fruit
trees and actively-growing turf.
Use fertilizer wisely
Using more fertilizer than the label recommends
is never a good idea. Carefully read and follow label instructions when applying
fertilizers. If you can’t read the small print on the label, go online and
increase the font size for easier reading. Too much nitrogen can cause excessive
growth and increased pest and disease problems. Excessive growth demands more
water, too. Salts in nitrogen fertilizers also can damage roots.
marketed in two categories—inorganic or chemical fertilizers and organic.
While organic fertilizers are derived from plants and animals (seaweed, fish,
bone meal, etc.), they can still be harmful to the environment and contribute to
surface and ground-water pollution if used improperly.
When fertilizer is
needed, use a slow-release type that will nourish plants throughout the growing
season and is less likely to runoff into storm drains. Use the recommended rate
of application and fertilize at the optimum time for the plants being fed.
Always keep fertilizer off hard surfaces like driveways and walkways where it
can easily be washed into gutters and down storm drains. The responsible use of
fertilizer is a key component to being stewards of the environment.
For more information