Seveland – Keep your lawn healthy to enjoy greener lawns and bluer waters

By Madeline Seveland, Carver County Water Management

Healthy lawns soak up rain and can prevent stormwater runoff, thus keeping polluted water out of our lakes and rivers.
As we look to the warm weather and season of yard care, here are some tips for establishing healthy lawns and using fertilizers and herbicides. Proper application of fertilizers and herbicides keeps them onsite where you get the most for your money and they don’t runoff into our lakes and rivers.
1. Get a soil test and learn what your soil really needs! Get test info at soiltest@umn.edu or (612) 625-3101.
If results show fertilizer is needed, use a slow-release fertilizer. They are safer for lakes and rivers and are more evenly distributed and less work to apply over the season.
Slow release fertilizers can be harder to find. Look for organic fertilizers containing animal manures, corn gluten meal or “stabilized nitrogen,” and avoid those containing ammonium.
Follow your soil test result’s guidelines, not the guidelines on the fertilizer bag. The best time to fertilizer is actually late summer – early fall.
Remember turf grass can only use a limited amount of nutrients. Excess nutrients applied are washed into lakes and rivers and cause algae blooms.
2. Leave grass clippings on the lawn when mowing and mulch/shred leaves in the fall. This is equal to one application of FREE fertilizer a year. Do not blue grass clippings or leaves into the street. They will wash into stormdrains and into lakes and rivers. It only takes one bag of organic material (clippings and leaves) to create 100 lbs of algae in a water body.
3. Spot treat for weeds. Weeds grow where grass is thin and weak. So before jumping straight to herbicides, try and figure out why that area of lawn is stressed, fix the underlying cause and reseed those areas in fall when there is less competition from weeds.
If you feel you must use herbicide, determine if your weeds are annual (lives one year) grass weeds, perennial (lives more than one year) grass weeds, annual broadleaf weeds or perennial broadleaf weeds. Most commonly treated are broadleaf weeds. For annual broadleaf weeds (cocklebur, lambs quarters, ragweed, etc.), use a post-emergent herbicide when the plants are very young and weak (in June).
For perennial broadleaf weeds (dandelion, broadleaf plantain, thistle, clover), it’s most effective to treat in the fall when the plants energy is directed towards its roots. Remember to ONLY treat problem areas with herbicides, not entire turf grass surface, this is better for lakes and rivers and saves money.
Do not use weed and feed mixes because the optimal time for fertilizing and weed control is different.
4. Remove thatch! Thatch is decaying plant matter which builds up at the soil level and is caused by excess fertilizing, not by mulching grass clippings. Thatch denies grass roots air, water and nutrients they need.
To break down thatch, put down organic matter like compost or mulched leaves to stimulate soil microbes. If it’s so bad that water can’t penetrate the thatch, remove it with a stiff rake.
5. Water thoroughly but precisely. Turf grass requires ONLY one inch of water per week to remain green during the growing season.
Don’t over water as excess water depletes turf nutrients and wastes water. Buy a rain gauge to measure rain water and only water enough to make up for little or no rainfall that week. To measure one inch of water, put an empty tuna (or similar) can on the grass. When it’s filled, one inch of water has fallen.
6. Mow high! Taller turf grass produces deeper roots which are key for survival in low rainfall times as they store more moisture and absorb more nutrients. Taller turf also provides more area for photosynthesis, the energy making system in plants. Keep turfgrass at a height of three inches.
For more information on obtaining healthy yards, visit University of Minnesota’s Sustainable Lawncare Information Series at www.sustland.umn.edu/maint/maint.htm.

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