Maintaining a Care-Free Lawn
Lawn grasses are by nature tough, resilient plants, yet they do require ongoing care. The most important lawn-keeping tasks are fertilizing, watering, mowing, preventing pests and diseases, and weeding. If you think of lawn grasses as low-growing foliage plants, valued for their leaves, it's easy to work with their natural growth cycles.
The Need to Feed
Unlike deeply rooted perennials, shrubs, and trees, grass roots seldom venture far into the soil, which limits their access to nutrients and water buried deep below the soil surface. At the same time, their crowns are constantly growing, producing new leaves. This rapid growth depletes nutrients that are naturally available in the topsoil, where the root are, so regular fertilizing is necessary to keep the lawn strong, healthy, and free of weeds.
All grasses crave nitrogen, the nutrient that powers the growth of new leaves. However, too much nitrogen creates a quick flush of green top growth without supplying other nutrients needed for root growth or to support the plants. Grasses perform best when given a slow, steady supply of a fertilizer that contains all three primary nutrients: nitrogen, phosphorus, and potassium. Such a balanced fertilizer promotes top growth, root development, disease resistance, and hardiness.
One of the best ways to fertilize the lawn is to use a mulching mower. These rotary mowers pulverize the nitrogen-rich clipped blades into tiny pieces and spread them back into the soil, where organisms break them down to release nutrients. Don't worry about leaving ugly clumps of cut grass on the lawn; clippings from mulching mowers are so small that they sink invisibly between the blades. If you don't have a mulching mower, you can use a regular mower without a bag. If you cut as often as needed to remove no more than one-third of the top growth, the small dippings will disappear.
When selecting a commercial fertilizer, look for a formula designed especially for lawns, such as an 8-2-2 formulation. Stay away from spray-on liquid fertilizers, which supply a blast of nitrogen that is used up quickly or may even run off before plants can use it. A granular fertilizer, especially one that acts slowly, is best. Organic fertilizers are preferred, not only because they release their nutrients gradually but also because they will not chemically burn grass, or cause it to turn brown, with an overdose. They also encourage the beneficial organisms that break down organic matter in the soil, releasing nutrients in a soluble form that grass roots can absorb.
It's important not to fertilize grass too much or too often. Twice a year is usually sufficient, using a fertilizer designed for blade development before plants start their active growth and using one designed for root development before plants go into dormancy. In cold climates, fertilize in spring and fall. In warm climates, fertilize in early and late summer. Read the package directions for recommendations on the proper amount to apply.
To ensure even coverage, invest in a drop spreader. This handy piece of equipment has a hopper set between wheels that releases fertilizer in a fixed amount as you roll it over the lawn and is very easy to use. Most fertilizer packages will tell you how to calibrate the spreader opening so that you apply exactly the right amount.
Watering Wisdom
Like every plant, grass needs water. But you really want to water the soil, which is the reservoir for the roots, rather than the blades themselves. Sprinkling the grass lightly every few days does more harm than good, because water never has a chance to sink deep into the soil. As grass roots rise to the surface to seek water rather than reaching deeply into the soil, the lawn quickly succumbs to drought and summer heat.
Lawns need at least 1 in (2.5 cm) of water per week. Let the soil, light, and climate be your guide. Heavy clay soil holds moisture longer than sandy soil, which lets water pass right through. And lawns in light shade or cool climates will stay moist longer than those baking in sun in a warm climate. It's time to irrigate when the blades wilt or lose their springiness when you step on them. You can also check the need for water by digging up a little plug of turf If the soil is moist, there's no need to water, and you can simply push the plug back into its hole. If it's dry, apply water.
Lawn sprinklers are the most convenient way to cover large areas. Automatic impulse systems are the most efficient but are expensive to install and may not be necessary in regions that usually have plentiful rainfall. If you have a portable surface sprinkler that revolves or oscillates, make sure it is in good condition so that the coverage is as even as possible.
Whatever type you use, the goal is to water slowly and deeply, so that moisture has a chance to sink to the roots, about 4-6 in (10.2-15.2 cm) deep, without running off or pooling. Water early in the morning on a still day, so that grass blades can dry off before sunset and water is not blown away from its target. Never water at midday, when much of the moisture is lost to evaporation before it hits the soil and wet grass can burn in the sun. To gauge the amount of water reaching the lawn, scatter several small cans beneath the sprinkler, each marked with a line 1 in (2.5 cm) up from the bottom of the can. Note how long the sprinkler must run to fill the can to the line. That's the amount of time you should run the sprinkler when watering in the future.
During drought, when municipal ordinances often prohibit lawn watering, don't worry. Most grasses simply go dormant and will spring back to life when moisture returns. In arid regions, where every drop of water is precious, consider planting a drought-tolerant grass species, such as buffalo grass. You can also cover as much space as desired with drought-tolerant groundcovers, such as low-growing shrubs, perennials, or even herbs, such as thyme or lavender, which thrive in arid places.
Know How to Mow
Proper mowing keeps grass height under control, encourages root growth, and discourages weed growth and disease. The optimum height depends on the species as well as the lawn use. Fine-bladed grasses used for display lawns and some grasses grown in warm climates do best at about 1 in (2.5 cm). Coarse-textured grasses are used for high-traffic lawns and many grasses recommended for cool climates should grow to 3 in (7.6 cm) or more.
The basic rule for mowing height is to take off no more than one-third of the blade each time you mow. If the ideal height for your grass species is 2 in (5.1 cm), mow when it reaches 3 in (7.6 cm). Taking off a small portion of the blades causes the least shock to the plants and leaves plenty of blades to make food for the roots. If blades are cut too short and can't supply enough food, the roots will grow poorly and weaken the plant, allowing disease to take hold. Longer blades also shade out weed seedlings, and die vigorous roots that result will keep most weeds from getting a foothold.
The ideal height can vary according to season. When grasses are growing actively, you can keep the blades a little shorter. Active growth occurs in spring and fall in cold climates and during summer in warm areas. During periods of stress from drought or heat, cut the blades higher. Grass growing in shade also should be allowed to grow 1 in (2.5 cm) longer than the same grass grown in sun, so that it has more surface exposed to light to help it manufacture energy.
Preventing Diseases and Pests
Fungal infections can sometimes crop up in lawns, such as brown patch and leaf spot, which usually appear as brown patches or dead spots in the lawn. Lingering dampness contributes to the problem, so correcting drainage problems that allow water to stand on the lawn helps prevent many diseases. Over-fertilization can also contribute to disease, because a lawn that grows too lush and thick holds morning dew for several hours. Also avoid evening watering to reduce the amount of time that your lawn is wet, because many fungal spores become active in the cool, damp hours of evening.
A healthy lawn will tolerate light insect feeding by common pests including sod webworms and chinch bugs. But in areas where June beetles or Japanese beetles are numerous, their larvae can seriously weaken lawns as they feed on grass roots in spring. The larvae of both types of beetles are small whitish grubs, easily found by digging up a patch of troubled grass in spring. For long-term control, apply a biological insecticide called milky spore, which contains beneficial fungi that kill the grubs and then persist in the soil, offering protection for years. Apply according to label directions.
Keeping Out Weeds
Weeds interfere visually with the uniform carpet effect that lawns provide. A few invaders do little harm, but large patches of weeds rob water and nutrients from the grass, weakening the lawn. Healthy, vigorous lawns are naturally resistant to weeds. If you fertilize properly, water deeply, and mow high, the grass will grow so thick that weeds won't have a chance. However, stressed lawns are vulnerable to dozens of weed species. Some, such as chickweed and crabgrass, are shallow-rooted annuals that die back after setting seed. Others, such as plantain and dandelion, are tenacious, deep-rooted perennials and will return year after year.
To halt the spread of annual weeds, you need to stop adult plants from dropping seeds and stop seeds from sprouting. Pull up annual weeds before they can set seed. If seedheads are already visible, use a
bag attachment when mowing and compost the clippings, because compost piles often become hot enough during decomposition to destroy the seeds.
If seeds drop, you can spread a commercial pre-emergent herbicide, which is a substance that prevents the seeds from developing. There are several broad-spectrum granular pre-emergents available at garden centers that you can broadcast with a fertilizer spreader. An organic pre-emergent derived from corn is also now available from mail-order garden suppliers. Because crabgrass is so common, there is a pre-emergent designed just to control this weed.
Apply weed preventers according to package directions at the right time, which is shortly before weed seeds are germinating in your region.You will not be able to spread grass seed for the length of time designated on the package label after applying a pre-emergent weed preventer, because it will also keep grass seed from sprouting.
Perennial weeds must be dug out, roots and all. The easiest time to do this is when plants are young, with small roots, and after a rain, when the soil is soft. Be sure you take out the entire root, especially of deep-rooted weeds, such as dandelion or those with spreading, fibrous roots, such as violets.
You can also apply an herbicide for perennial weed control, which is usually a liquid that you can either spray on individual weeds or spread on a large area with a hose-end sprayer. No one product destroys all types of weeds or is safe for all grasses, so read the label carefully and use according to package directions. To be most effective, these herbicides should be applied when the perennial weed is actively growing, usually just after the plant flowers. Weeds should begin to shrivel and die in about 10 days.
It is important to follow safety practices when spraying herbicides. Notify your neighbors that you will be spraying. Spray on a still day, so that wind won't carry it onto desirable plants. Wear long-sleeved and long-legged clothing, socks, and protective gear, including a respirator, goggles, and gloves. Do not eat, drink, or touch your hands to your face while spraying and bathe immediately after applying the product.