Now that the snow has (mostly) melted, spring is close on the horizon. It is time to start thinking about fertilizing the perennials in our gardens. Perennials should be lightly fertilized at emergence, when they first poke their noses up, in the spring. Why now? Let us use peonies as an example. From flowering in May, to dormancy after a hard freeze in Oc [...]
Now that the snow has (mostly) melted, spring is close on the horizon. It is time to start thinking about fertilizing the perennials in our gardens. Perennials should be lightly fertilized at emergence, when they first poke their noses up, in the spring.
Why now? Let us use peonies as an example. From flowering in May, to dormancy after a hard freeze in October, they do not grow. Not a new stem or leaf is added to the plant and the existing leaves do not grow any larger. They do not grow after blooming but they do carry on photosynthesis all season long. The food made in photosynthesis during the summer is translocated down and stored in the roots so we will have a larger, more glorious plant next year. Many perennials have similar growth patterns. All growth happens between emergence and flowering. This is why it is important to have nutrition in the root zone at emergence to fuel the vegetative growth portion of the plants life cycle.
Most perennial flowers are not heavy feeders. They should be fertilized each year but only lightly. Nitrogen is the key element for growth and should be applied each year. A little nitrogen is important but a little more nitrogen can lead to very soft, and succulent tissue that is more susceptible to insects and diseases. Phosphorus is important for healthy plants but it can build up in the soil and can easily be carried off site attached to soil particles and contribute to pollution issues. Apply phosphorus only when a soil test indicates it is deficient. A 3-1-1 (12-4-4), 2-1-1 (16-8-8) or 3-1-2 (18-6-12) fertilizer ratio is ideal. If you prefer organic fertilizers then blood meal, fish emulsion, soybean or alfalfa pellets are all good choices. Note that bone meal because of it's phosphorus content should be used only when a soil test indicates a deficiency of phosphorus. Chemical fertilizers are readily available to the plant shortly after application. Organic fertilizers must first be transformed - they must breakdown before the nutrients within are available to the plant. They need to be applied a month or two earlier to be available at the proper time to fuel a perennial flower's spring growth.
While we are on the subject of perennials, here is just a little reminder that we also have the Prairie Bloom program of recommended perennial plants from the trials at Kansas State University. In recent years we have added many new Perennial Hibiscus, Iris, Daylilies, Hostas, Shrub Roses, Ornamental Grasses and more to the list. Though they don't offer the continuous color of annual flowers, perennials are not to be overlooked when planning a garden. On the plant profiles from the Prairie Bloom list you can find the approximate first week of bloom for the perennials, enabling you to plan for some spots of color throughout the entire season.
Perennial Hibiscus 'Fantasia'