Extension Master GardenerSM Volunteers of Buncombe County

lime

Soil Tests: What They Tell You and What They Don’t!

“Have you done a soil test?” is one of the first questions Extension Master Gardeners ask if you’re starting a new gardening project. Do you know what a soil test can tell you—and what it can’t?

Soil Test Box and Sample Information Sheet

Useful information from soil tests:

  • Nutrients your plants need to grow
    • Primary macronutrients: Nitrogen (N), Phosphorus (P), and Potassium (K)
    • Secondary macronutrients: Calcium (Ca), Magnesium (Mg), and Sulfur (S)
    • Minor nutrients: boron, chlorine, copper, iron, manganese, molybdenum, nickel, and zinc
  • Soil acidity level (pH)

Your soil test will tell you the amount and type of fertilizer to use to provide the nutrients your plants need and how to adjust the soil pH to the appropriate level. It can also tell you if you have too much of certain nutrients! Overfertilizing can be as detrimental to your plants’ growth as too little fertilizer.

 Your soil test won’t tell you if you have:

  • Poorly structured soils
    • Plants may have difficulty getting established on sites where topsoil was stripped away, or soil layers were disturbed and/or compacted during construction.
    • Heavy clay soils, in particular, are difficult for roots to penetrate.
  • Too much or too little soil moisture
    • Poorly drained soils may prevent plant roots from getting enough oxygen.
    • Drought or fast-draining soils may lead to root damage/death from too little soil moisture.
    • Watering too frequently or not deeply enough can create moisture problems for plants in good soils.
  • Plant competition
    • Shallow tree roots or the roots of plants spaced too closely may compete for soil nutrients.
    • Allelopathic plants—such as walnut trees—may act as herbicides and keep nearby plants from thriving.
    • Shade from other plants may inhibit growth of sun-lovers.

So, knowing the proper nutrients and soil pH is a start, but having your plants thrive means making sure your soil has appropriate soil structure and moisture, and providing them with appropriate space and plant companions.

Article by Debbie Green Buncombe County Extension Master GardenerSM Volunteer

For more information:

 Soil testing in North Carolina:

https://content.ces.ncsu.edu/extension-gardener-handbook/1-soils-and-plant-nutrients#section_heading_7241

 “What a Soil Test Does Not Tell You” (scroll down to last article in this newsletter):

https://hnr.k-state.edu/extension/info-center/newsletters/2018/Feb20_2018_7.pdf

Allelopathy in walnut trees:

https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-021/430-021_pdf.pdf

 

 

 

Lawn Maintenance: How Much is the Right Amount?

How do you keep your lawn looking respectable year-round? You know you have to mow, but how much else do you need to do? Do you want a great lawn or a “good-enough” lawn? Here are tips on how to have the lawn you want.

Photo by Joey Williamson, Clemson Univ ExtensionMowing
Mowing is key to keeping your lawn presentable, no matter what! Your goal: keep your cool-season grasses three inches tall, mowing off no more than a third of the height at a time. Never let your lawn get above five inches. Grass may need mowing anytime of the year that temperatures get into the 70s.

Lawn growth varies wildly and individual lawns need individual evaluation. Overheard last week: “We’ve had so much rain that my husband is mowing the lawn every four days!” “Well, we’ve had so little rain that I haven’t mowed in three weeks!” Plan accordingly—fixed schedules won’t work!

Grasscycling
Many mowers will bag your cut grass, but you can save time and money—including on fertilizer—by leaving the clippings on the lawn. Mulching mowers keep the clippings small so they quickly dry out. Turf specialists estimate those clippings provide about 25 percent of the nutrients your lawn needs each year.

If your mower leaves clumps of cut grass, you may need to mow more often, or be sure the lawn is drier. Break up clumped clippings to avoid smothering the remaining lawn. If you bag or rake clippings, use them elsewhere in your garden or compost—hot composting will kill weed seeds!

Core Aerate LawnCore aeration
Aerating helps root growth in compacted soil and is worth doing, especially in years you overseed your lawn. Aerate this fall or when growth starts up again in the spring. Rent equipment that brings up small cores of lawn or hire someone to do the aeration. Just poking holes in the soil creates more compaction! Cores gradually break down—rake to break them up if they bother you. Mark irrigation system emitters and hoses so you do not damage them!

Watering
Lawns in active growth need consistent watering—an inch a week from rain or irrigation. Cool season grasses go dormant and brown up in the heat of summer. You may want to encourage dormancy to minimize maintenance. Dormant lawns may be able to go without rain for six weeks, but it is best to provide some watering every three weeks. Turf specialists advise that as little as ¼ inch may be enough.

Liming
Grass can’t effectively use nutrients if your soil is too acid. Many WNC lawns desperately need lime, but only a soil test will tell you how much. Lime takes awhile to work on soil pH—don’t expect immediate results. Test again in two or three years before liming again.

Fertilizer
Yearly nitrogen is a given, but some lawns need phosphorus, too—check your soil test! A lush lawn may require 2.5 to 3 pounds of nitrogen a year, but you can certainly use less, especially if you leave your grass clippings on the lawn. Plan to apply at least one pound of nitrogen every September and possibly another pound in October or November. If your lawn is still struggling, provide the remaining half-pound or pound in February. Fertilizing any later may lead to even lusher growth, but may make your lawn susceptible to fungal diseases come summer.

Dandelion weed in lawn
Dandelion weed in lawn

Weed management
With proper maintenance, you’ll find weeds aren’t as much of a problem. Identify your weeds. Pre-emergent herbicides can prevent crabgrass—an annual weed—from sprouting in bare spots. Decide if perennial weeds justify treatment. White clover may be a desirable addition to your lawn if you don’t need a uniform stand of grass. If you have a few dandelions, or other broadleaf weeds, try digging them out. Pervasive aggressive weeds may justify broadleaf herbicides.

Diseases and insects
There are many lawn ailments and pests, but with proper maintenance, damage is minimal, especially if you employ proper lawn maintenance practices. North Carolina State University provides many resources for identifying and treating lawn problems.

Article written by Debbie Green, Extension Master Gardener Volunteer.

Photo of woman mowing lawn courtesy of Joey Williamson, HGIC Horticulture Extension Agent, Clemson University,
http://www.clemson.edu/extension/hgic/plants/landscape/lawns/hgic1203.html

Free Lawn Care App:
http://www.lawncare.ncsu.edu/
Maintenance Calendar:
http://www.turffiles.ncsu.edu/turfgrasses/fine-fescue/lawn-maintenance
Organic Lawn Care:
http://www.turffiles.ncsu.edu/Files/Turfgrass/Articles/Bruneau_A/2008/Organic_Lawn_Care__A_Guide_to_Lawn_Maintenance_and_Pest_Management_for_North_Carolina.pdf
Weed ID:
http://turfid.ncsu.edu/

Time for Lawn Assessment: Maintain, Renovate, or Replace?

Mid-August and early September are good times to focus on lawn care. This blog is the first of a three-part series on lawn assessment, replacement, and maintenance.

Lush LawnTake a good look at your lawn. Is it struggling? That’s not surprising given the punishing heat and drought this summer! Don’t despair, though, we have answers for you.

The right grasses
A healthy lawn starts with choosing grasses. Here in Buncombe County, we grow fescues and Kentucky bluegrasses, cool season grasses that look good much of the year, but languish in the summer heat. We don’t grow warm season grasses—such as zoysia and bermudagrass which like the heat of summer—because they brown up as they go dormant in the cooler weather we have most of the year.

Sun, water, and nutrients
Like all plants, grasses require sun, water, and nutrients to thrive, so even the right grasses may die out, or be quickly overrun with weeds. Grasses need sun much of the day, so look carefully at where you’re trying to grow a lawn. Give up on areas where buildings, trees, or shrubs shade your grass.

Too little and too much water are both problems for lawns. Avoid grasses in very dry or very wet areas of your yard unless you can provide irrigation or improve drainage, respectively.

Lawn grasses often require lime to be able to take advantage of soil nutrients and nitrogen fertilizer annually. Soil testing at least every three years will tell you how much lime to add and if you need phosphorus or potassium in addition to nitrogen when you fertilize.

Mowing considerations
Don’t have more lawn than you can keep regularly mowed. Cool season grasses do best mowed to three inches, cutting off no more than an inch or so of the grass blade. In the mountains, slopes pose another obstacle to having a great lawn. Although grasses can help prevent erosion, don’t plant a lawn where you won’t feel comfortable mowing!

Decision time
If your lawn is growing in all the places you want it to grow, you need only to follow a good maintenance plan this fall to have the lawn of your dreams. (Watch for coming blog!) Not your reality?

Renovate as temperatures begin to drop after mid-August. NC State turf specialists recommend overseeding bare spots with a seed mix of tall fescue cultivars at the rate of 6 pounds per 1000 square feet of lawn. Fertilize with a lawn starter fertilizer high in phosphorus. You must keep your seeds moist with light, gentle, watering, which may need to be done more than once a day if the soil starts to dry.

If your lawn is in dire condition, consider replacement by killing off the existing grass and weeds to put in a new lawn or lawn alternative. Now is the time to begin the replacement process! Kill a lawn by:

  • Smothering: burying the surface under several inches of mulch, such as arborist’s wood chips.
  • Solarizing: covering with clear plastic for 4 to 6 weeks. (This is unwieldy and kills off beneficial soil organisms.)
  • Stripping off the turf with a sod cutter. (You may rent these.)
  • Using a broad-spectrum herbicide that will kill both grasses and broadleaf weeds.

For smothering, solarizing, and stripping, you can cut the lawn low to help kill the plants. If you use herbicides, be sure you apply to an actively growing, uncut, well-watered lawn, and be very careful you don’t allow any of the product to drift onto desirable plants or shrubs.

While your lawn is dying, consider what you want in its place! We’ll have some suggestions!

Article written by Debbie Green, Extension Master Gardener Volunteer.

For help with grass and weed identification, go to http://turfid.ncsu.edu/.

Contact Us

Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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