NDSU Extension - Stark & Billings County


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Time to Fertilize Your Lawn

Did you know the best time to fertilize your lawn is now? It’s true! The key to a healthy turf is a thick root system, and now is when your turf focuses its energy on growing roots.

Let’s compare fertilizing lawns in April versus now. After we fertilize our lawns in April we feel rewarded when the grass greens up. But this boost of new grass blades comes at the expense of a deeper root system. You have to mow your lawn more often, and your turf may become more vulnerable to drought stress in summer.

In contrast, fertilizing in fall will:

  • Repair any damage that occurred to the lawn over summer.
  • Lead to a thicker turf and a stronger root system this fall.
  • Help the turf to tolerate stresses such as drought, diseases and winter.
  • Lead to a quicker green-up next spring.


What type of fertilizer is best?

A fertilizer bag has three numbers, indicating the percentages of nitrogen, phosphate and potash. Nitrogen is the most important nutrient. Look for a fertilizer with at least 25% nitrogen. Select a fertilizer that contains some slow-release nitrogen (sulfur-coated urea, urea formaldehyde and IBDU). This will gradually feed the lawn this fall and next spring. The second number, phosphate, is abundant in our soils and is rarely needed in established lawns. The third number, potash, will help our lawn to tolerate stresses, including our winters. Most winterizer fertilizers contain 5–10% potash.


Should I use a weed-and-feed fertilizer?

These fertilizers are okay at feeding lawns and okay at killing weeds, but not great at either. Here’s why:

Bad timing. The best times to feed a lawn (late May and early September) are not the best times to control weeds, namely crabgrass (late April) and broadleaf weeds (mid to late September).

Bad for the environment. Landscapes (including trees) grow better when herbicides are sprayed only where needed on lawns. Using weed-and-feed fertilizers puts toxic chemicals everywhere, even in areas with no weeds.

Bad control. Herbicides must be absorbed by weed leaves to work. Some small-leafed weeds such as black medic and clover cannot hold onto the granules and absorb the herbicide.

As an alternative, spot sprays of liquid herbicide applied directly onto weedy areas can be applied to kill weeds at the most effective time and in a more effective manner.

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