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Fertilizing Perennials and Grasses

Native For some gardeners, fertilizing is sort of like the final frontier of gardening.  They know that fertilizer can be a good thing, but they also know that too much can be disastrous.  It seems like we all know someone who “burned up” their plants with fertilizer that (they claimed!) was applied properly.  In the nursery we apply several forms of synthetic fertilizers.  We use a water-soluble fertilizer (WSF) for some species and for others we use a controlled release fertilizer (CRF). We have also used a turkey compost fertilizer with very good results so if you don’t like synthetics there are good options for you.

What we’re going to stress here is to apply fertilizers in moderation.  Perennials and grasses do not need much in the way of fertilizer and too much leads to rampant growth and flopping.  The link below is an excellent article about fertilizing perennials and grasses from Michigan State University Extension.  A brief summary of their article is outlined below.

  • Sandy, or low organic soils can benefit from a light, 1/4-strength application of fertilizer.  Simply divide the recommended amount by 4 and apply in a general area around the root zone.  If you’re using a general fertilizer in pellet form spread the fertilizer out on the soil above the roots.  Do not leave it in a pile on the soil.  Apply pellets when the foliage is dry so that it doesn’t stick to leaves causing them to burn.  Keep fertilizer away from the crown of the plant.
  • A controlled release fertilizer (CRF) is an excellent way to slowly feed your plants over a long period of time.  As with all fertilizers this should be applied in the spring when plants are vigorously growing vegetatively.  Topdressing the fertilizer or spreading it in the general area on the soil around the plant is generally how pellets are applied.  Pellets can also be applied at planting time into the bottom of planting hole, but this can concentrate the fertilizer into a small, defined area so be careful and follow all label instructions.
  • A soil test can help determine whether you need to fertilize.
  • A layer of leaf compost often will supply needed nutrition over the course of a growing season if applied in a 1″-2″ layer.
  • Do not fertilize perennials in late summer as this may promote unwanted vegetative growth which will not have enough time to harden off prior to winter.

The complete article can be found here:

Fertilizing established perennial gardens – feed ‘em and weep – MSU Extension