Lawn and garden tips for Middle Tennessee

A fresh layer of mulch holds moisture, keeps weeds down and finishes a bed, as long as it is not piled against trees and shrubs.

Two to three inches is enough. Deeper than that can keep the soil too wet and starve roots of air.

Pull mulch a few inches back from tree trunks and shrub stems. "Mulch volcanoes" piled against the bark hold moisture against it and invite rot and pests.

Spring is the usual time to refresh beds. A crisp edge between the bed and the lawn keeps the mulch in place and makes the whole yard look sharper.

Crabgrass sprouts when the soil warms to about 55°F. A pre-emergent applied just before then stops most of it before you ever see it.

In Middle Tennessee that is usually March. A handy natural signal is forsythia: when it is in full bloom, the soil is close to germination temperature.

Water the pre-emergent in as the label directs, and do not aerate afterwards, which breaks the barrier.

Remember the trade-off: the same barrier stops grass seed, so plan any spring seeding around it.

Tall fescue, the most common lawn grass in Middle Tennessee, stays thicker and greener when it is cut at 3 to 4 inches.

Taller grass shades the soil, keeps roots cooler and crowds out weeds like crabgrass. Bermuda and zoysia lawns are the exception: they look best kept shorter, around 1 to 2 inches.

Whatever the grass, remove no more than one third of the blade at a time. In the spring flush that can mean mowing every five days instead of every seven. Keep the blades sharp: a dull blade tears the grass and leaves brown, frayed tips.

Leave the clippings on the lawn. They break down quickly and return nitrogen to the soil.

About an inch of water a week, rain included, applied in one or two deep soakings builds deeper roots than a daily sprinkle.

Water in the early morning, when there is less wind and evaporation and the grass dries quickly, which helps limit disease. Evening watering leaves the lawn wet overnight.

Clay soil takes water in slowly. If it starts running off, split the watering into two shorter cycles an hour apart.

A tuna can or rain gauge on the lawn is an easy way to see how much water a sprinkler actually puts down.

September and early October give cool-season grass warm soil and cool air: the best window of the year to thicken a thin lawn.

Core aeration pulls small plugs of soil, which relieves the compaction common in our clay and lets seed, water and air reach the roots. Overseed right after aerating so the seed falls into the holes.

Keep new seed lightly moist, usually a short watering once or twice a day, until it is up and growing, then water less often and more deeply.

Skip crabgrass pre-emergent on areas you are seeding: it stops grass seed from germinating, too.

A thick, wet layer of leaves blocks the light fall-seeded grass needs. Light layers can simply be mowed back into the lawn.

If you can still see most of the grass through the leaves, mow over them. The shredded leaves break down into the soil.

Heavier layers should be blown or raked off, especially on newly seeded areas and before a long rainy spell.

Clear leaves out of beds and gutters too, and keep them off walkways where they get slick.

When a shrub flowers tells you when to cut it: prune at the wrong time and you remove next season’s blooms.

Spring bloomers such as azaleas, forsythia and many hydrangeas set their buds the year before. Prune them soon after they finish flowering.

Summer bloomers such as crape myrtle and butterfly bush flower on new growth, so late winter is a good time to shape them. Avoid topping crape myrtles; thin crossing and inward-growing branches instead.

Hold off on heavy pruning after late summer. New growth needs time to harden before the first frost.

A soil test tells you what your lawn and beds actually need, so you are not guessing with fertilizer or lime.

The University of Tennessee Extension offers soil testing through its county offices. The results show pH and nutrient levels with recommendations for your grass or plants.

Many lawns around here lean acidic. If the test calls for lime, late fall and winter are good times to apply it, since it works slowly.

Testing every few years is plenty for an established lawn.