Spring Perennial Garden Fertilization
. . . fertilizing established perennial gardens
With proper care and conditions, perennials return, often increasing in size, each year, unlike
annuals, which live a single season, give their all and die.
Perennials are in for the long haul. Plant them once, and they come back every year, so you don't have to
plant again. Perennials naturally take at least three years to
complete their life cycle. They generally flower for shorter periods of time, each type with its own timing,
but their variety in bloom times, and their textures, colors and forms keep landscapes looking fresh and
vibrant. Proper fertilizers help perennials keep their beauty and vigor, and prepare for coming years.
Compared to natural settings, perennial beds are crowded and competitive. All those lovely flowers contend
for the same nutrients. Even plants that naturally thrive in poor soil benefit from fertilizers in garden
settings. Feed them properly, and forget about weak, lanky plants or few blooms. High-nitrogen fertilizers,
including common houseplant foods, can stimulate leafy, green, grassy growth. But flowering perennials
need fertilizers that support prolific blooms.
Smart gardeners know that heavy fertilization of perennial garden plants leads to flopping over
half-way through the season.
Perennial flowers, ground covers and grasses generally don’t need a lot of fertilizer and, in fact, some will
react negatively if too much is applied.
Browning and yellowing of
leaves from over fertilization.
An over-fertilized perennial will reward gardeners with excess
growth that flops over and becomes leggy half-way through the season. Over-fertilization can also affect
bloom performance, producing ample foliage at the expense of blooms. Many perennial experts
recommend no fertilization when plants are in a healthy garden soil.
However, if your soil is composed primarily of sand with little organic component, your plants will most
likely benefit from routine, light fertilization.
Understanding the types of plants and their natural growing range will enable you to create a growing
environment similar to the plant’s native habitat. It is helpful to keep a watchful eye and journal of plant
behavior in hopes to correct situations later such as leggy growth and poor performance.
Broadcasting a slow release fertilizer is the best choice to meet season-long plant nutrient requirements,
but you can also use a balanced fertilizer such as 20-5-10. If your soil test indicates that you do not need
phosphorous, choose a product such as 20-0-10.
Slow release products are formulated to be effective for either a “3-4” month window or a
“5-6 month” window. If you top-dress and plan on using supplemental feed at any time during the
season, the 3-4 month product should work well. If you only intend on fertilizing only once during
the season, then the 5-6 month product should be used.
Side dress fertilizer.
You can also use the side dress method, applying several tablespoons of fertilizer (according to the
manufacturer’s guidelines) in the general root zone of each plant. Make sure not to allow fertilizer granules
to cluster in the crown of the plants as it may cause burning. In the early spring, cool soils can have an
effect on uptake of certain nutrients, at times making the foliage appear light green or yellow (nutrient
deficient). If this appearance does not diminish as the season progresses, spot treat with liquid feed to
bring about a quick green up.
By applying 1 inch of compost
or leaf mold
to your garden every year, additional fertilizing can often be
eliminated altogether. This is where having a good understanding of each plant’s needs while observing
leaf color and growth habit will help you avoid excess fertility.
Top-dressing a perennial bed with 1 to 2 inches of compost will provide season-long fertility for most
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