Keep up the grass: Tips from a lawn expert

Sage advice from a Boisean who takes care of some of the most-used lawns in town.

Special to the Idaho StatesmanMarch 14, 2014 

  • FREE CLASS ON APRIL 2

    Dave Beck, the author of this story and the turf manager for Boise Parks and Recreation, and Toby Norton, a landscape architect with the city of Boise, will present "Lawn & Landscape" Wednesday, April 2.

    Other classes from Boise Parks and Recreation professionals include:

    • "Tree Selection and Planting," March 19

    • "Tree Problems," March 26

    • "Roses and Irrigation, April 9

    All classes are free, but you must register online at parks.cityofboise.org, by emailing bpr@cityofboise.org or calling 608-7700.

    The classes are from 6 to 8:30 p.m at the Boise Main Library Hayes Auditorium, 715 S. Capitol Blvd.

STARTING A LAWN FROM SEED

Planting seed is a lot cheaper than sod, and you have more choices over what grass species you want to grow.

Be sure to have good soil-seed contact. That's critical. It's easy to accomplish with a hydro seeder, where a mulch and "tackifier" stick to the seed and hold it to the ground. If you're sowing your lawn yourself, rake the seed into the soil or go over it with a roller.

The best time to sow lawn seed in the Valley is August or September when the ground is warm enough to germinate the seed and the young seedlings get to grow in cooler temperatures ideal for most lawn species in Idaho. You can also seed in the spring, but your grass will have to compete with more weeds that naturally germinate then, such as crabgrass.

Either way, the seed must not be allowed to dry out. Water lightly every day, sometimes multiple times per day. As the seedlings emerge, you can gradually increase the time between irrigation.

BILLBUGS

If you live long enough in Idaho you'll eventually come across a billbug, a little beetle with a prominent snout, or proboscis. Its grubs cause the most damage. They are white and legless, with a brown or yellowish head. They chew the roots. A billbug infestation looks like blotchy, drought-stressed grass that doesn't recover with more water. If you pull at the stressed grass, clumps of it will come out.

Billbugs overwinter as adults, then lay their eggs in the stems in spring. You may see the adults crawling around on the sidewalk or other hard surface. The eggs hatch and the larvae eat their way down through the crown and into the soil.

If you see a billbug-damaged lawn, make a note of its location. To keep it from getting worse, treat it right away with an insecticide certified for billbug control. Read the label. (I know, who does that, right?) Seriously, read the label.

Now, you are in repair mode. Overseed the damaged area with your favorite seed mix. Water lightly and frequently. Be sure the soil has phosphorus and potassium for the root repair.

The following spring, get out your notes and stage a pre-emptive strike. Spring application is most effective because you're killing adults that are laying eggs and the residual chemical will kill the vulnerable larvae as soon as they hatch. Contact your county Extension office for more specific hatch times.

IRRIGATION

We live in a desert. We need to irrigate our lawns. Water deeply and infrequently to encourage the development of a healthy root system.(Remember, if the top layer of soil is always moist, why grow deep roots? The roots will stay in the top layer of the soil, making them vulnerable to a drought or irrigation malfunction.)

How much water? Give the lawn about 1/2 inch of water each time you water. In the hottest months of summer, you'll need about 2 inches a week. The Parks Department has a weather station that gives a number for how much water is required on a daily basis. We feed this information into our irrigation controllers to deliver just the right amount of water. You can go to Agrimet (www.usbr.gov/pn/agrimet) to get the same data for free.

Water deeply: Regardless of the type of grass you have, it's more important to focus on the top 3 to 6 inches of the soil, where 80 percent of the root mass is.

Imagine your soil is a cup. You should water to the top of the cup each time you irrigate and allow the soil to dry to just before the wilting point. Do not water past soil capacity. It'll just run down the drains.

Dormancy: Sometimes it may be best to allow your grass to go dormant, even turn brown. But don't let lawns go for more than 4 to 6 weeks without a drink. Water shortages or cost may force this less-than-ideal situation. The good news is it's OK for the plants.

On the other hand, erratic watering - water here or there but never enough, keeping the grass at the wilting stage, repeated dormant/wake cycles - stresses the plant. It's better to allow the grass to go dormant and keep it dormant.

Any turf-type grass in Idaho will die after about a month if there is no water at all delivered. If you're wondering if the lawn will come back, take a look at the crown. A living crown will be white, a dead crown is brown and crusty … like a desiccated pea.

FERTILIZING

Your lawn needs three macronutrients: nitrogen (N), phosphorus (P) and potassium (K). The three numbers you see on a bag of fertilizer describe the amounts of NPK it contains.

Typically, nitrogen is the limiting ingredient to growth. It's almost like magic: Add a little nitrogen and bam! - the lawn grows like crazy. Without nitrogen the grass is yellow, grows slowly and is invaded by weeds.

You may not need annual nitrogen applications, especially if you mulch your clippings when you mow. If the grass is so fast you're mowing twice a week, why add fertilizer? It's OK to skip a year.

We're using less phosphorus these days. In fact, our chief fertilizer has no phosphorus, which is a major water pollutant. (Some phosphorus is important for root growth, and it's fairly stable in the soil.)

If grass is yellow and "wilty," and you've added nitrogen and iron and haven't sprayed it with a deadly herbicide, then suspect low potassium. (For information on having your soil tested and more about soil nutrients, see page 10.)

When to fertilize: The parks staff applies slow-release fertilizer once in the fall (the most important time if you're only going to apply once) when grass is storing carbohydrates for winter. Our slow-release formulation doesn't load the soil with too much nitrogen at one time. A slow trickle of nitrogen applied in fall will improve the lawn's ability to green up in spring. If you're using a fast-release fertilizer, use less but plan to fertilize again a bit in the spring.

LAWN CHOICES

I think the best lawns are made of a mixture of grass species. I like blue/rye mixes (80 percent Kentucky blue, 20 percent perennial rye) for the look, wear, recovery and moderate water needs. Even better are blue/rye mixes that include fescue, about 40 percent perennial rye, 40 percent fescue, 20 percent Kentucky blue. You get the excellent wear tolerance of fescue, disease resistance of rye and the recovery of Kentucky blue.

If you're thinking about converting your lawn to a "natural" grass field consider gamagrass, Idaho fescue or Sheep's fescue. Some of the areas in Kathryn Albertson Park have been successfully planted with Idaho fescue and Sheep's fescue. I've seen some really nice "natural" lawns planted with gamagrass.

Grass mixes: Finding species that will grow well together and look good is hard. If you mix your own, you may end up with patches of grass going dormant sooner, off-color patches and dissimilar textures weaving about. Let the pros do the experimenting.

David Beck is the turf manager for Boise Parks and Recreation. He is certified in sports turf management by Georgia State University. He's been keeping hundreds of acres of turf green, healthy and beautiful for Parks and Recreation for more than 15 years.

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