Deb Babcock: Spring is best time to fertilize perennials
May 17, 2010
Steamboat Springs — The gardening catalogs that we all pore over at this time of year often show plants at their peak bloom-time, bursting with lush foliage and vibrant blooms. In order to replicate that look once the plants are settled into your garden, you'll probably need to fertilize them.
Shopping in the gardening section of your favorite store can be daunting; there are so many fertilizer choices. Instead of guessing which one to buy, take a little time to learn the difference between organic and man-made fertilizers and dry, water-soluble and slow-release formulas. All are fine choices, but some might fit your needs better than others. Regardless of which you choose, always apply according to the label directions.
Chances are, your perennials will get along just fine in your garden without any extra fertilization. However, they'll likely grow a little slower and not be as showy as the photos in the gardening books.
Although plants in the wild live off the nutrients found naturally in the soil, Mother Nature limits the number of plants and the varieties that a particular amount of space can sustain. In our gardens, we tend to crowd in lots of plants with many differing requirements that all compete for the limited amount of nutrients already in the soil. In order to achieve vibrant growth, we need to help them out with additional nutrients in the form of fertilizer and/or organic compost.
Because perennials use a huge amount of energy early in spring as they begin another season of growth, now is a good time to give them a boost. For your plants that are grown for the flowers they produce, your fertilizer should have plenty of phosphorus, which is the middle number on the package (for example, 5-10-5). Nitrogen, the first number, is needed for foliage growth. The third number, potassium, is needed for root growth and is especially helpful in fall, when plants store energy below ground, though it's not as necessary here as our soil generally contains plenty of potassium.
The three numbers refer to the percentage of each nutrient that is present in your package of fertilizer; the remaining percentages mostly are filler to help in application. A soil test will help you determine which nutrients, if any, are deficient in your soil.
Many gardeners tend to prefer organic fertilizers instead of man-made varieties, which have a tendency to put a lot of salt into the soil throughout time. Since organic fertilizers release nutrients much slower than man-made, they might not give you as much foliage growth and should be applied again in mid-summer.
Some perennials do better without any fertilization. Native wildflowers such as Echinacea (coneflower), penstemon and succulents such as sedum grow best when not fertilized.
If you work some compost or organic matter into the soil around your perennials at the start of each growing season, you'll also help plant growth through slow-release nutrients, as well as soil aeration and drainage.
Deb Babcock is a master gardener through the Routt County Cooperative Extension office. Call 970-879-0825 with questions.