Margaret Lauterbach: Get to work fertilizing ahead of the heat

Special to the Idaho StatesmanMay 23, 2014 

Now, before searing weather moves in, give your lawn a quarter of its annual requirement of fertilizer, unless you use a mulching mower that lets grass clippings themselves fertilize your lawn. Some of the newer grasses require less fertilizer than the old Kentucky bluegrass.

We apply one-quarter of what our old lawn needs in May, one-quarter in September, and one-half in November, just in time for grasses to tiller (send out new grass blades). Grass is brown and looks dead at that time, but it isn't dead.

Lawns need more than just nitrogen for fertilizer, they also need some phosphorus and some potassium too. Be particularly careful not to over-apply nitrogen, for that's what leads to thick thatch. A little thatch in lawns is normal, but over a half-inch thick is not. Thatch is a build-up of dead grasses beneath living grass that interferes with water and nutrient penetration.

Watch for billbug activity in your lawn and take steps to control them. Organic control is use of beneficial nematodes; non-organic is use of synthetic chemicals.

Some of the newer fescue grasses contain endophytes (bacteria or fungi) that control such lawn pests.

DANDELIONS: GOOD OR BAD?

It has been said that if people learned to appreciate dandelions, there'd be much less stress in the world. Dandelions are edible for humans, the greens especially tasty before the plant flowers. Flowers are used for wine.

Even so, homeowners usually strive to eliminate dandelions from their lawns.

People who hate dandelions usually try to control them with 2,4-D, a growth accelerant that will quickly send dandelions to flower and seed, starting a new cycle.

I applaud the local efforts to reduce pesticide use, but I'd prefer folks attacked the neonicotinoid pesticides that are killing bees. Just pulling dandelions will, if the activity is effective, reduce food available for bees. Unless the entire root is pulled, dandelions will return, at least two where one had been located.

2,4-D is not a neonicotinoid pesticide. The neonicotinoids responsible for honeybee deaths (colony collapse disorder) in a new Harvard study are imidacloprid and clothianidin. Both block insects' central nervous systems, killing them by paralysis. Both are approved, alas, by our EPA.

Imidacloprid is the active ingredient in the very long-lasting tree and shrub insecticides, and clothianidin in other pesticides, such as some that target corn rootworms. Both are very toxic to honeybees, and are persistent in the environment. The tree and shrub pesticide lasts a full year, so will be present when the tree or shrub blooms.

If you don't want dandelions to germinate in your lawn, mow at a height of 3 inches or taller. That height of a healthy lawn shades soil sufficiently that weed seeds fail to germinate. If you must rid your lawn of dandelions, use a nozzle to blast soil away from the root, then pull it up, the entire root.

Do not be tempted to spray dandelions with Roundup or any other glyphosate product. Years ago I saw a lawn pockmarked with brown patches belonging to a man who was intelligent and well-educated, but who had lost caution over dandelions and resorted to spraying Roundup. Yellow blossoms or white balls of seeds would have looked better.

I enjoy the sight of dandelions' cheerful color in early spring, early pollen and nectar available to honeybees and beneficial insects. I have some dandelions in my lawn, and many in garden paths. They're welcome there, perhaps choking out the weedy mallow.

Send garden questions to melauter@earthlink.net or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.

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