Given the unseasonably hot & dry weather over the last month in many parts of Canada, for many, the official arrival of summer of June 20th seemed a little late. Whenever the weather gets hot & dry, lawns start to change in appearance. The first indication of heat and drought dress is visible when your previously lush green lawn starts to take on a blueish / grayish tinge. When you mow the lawn or walk on it, you may notice that wheel marks and/or footprints don't bounce back as quickly as they did, earlier in the cool and wet spring conditions. While there are some areas getting more rainfall, we are at a point now that many residential lawns are now starting to show significant signs of summer stress.
When this starts happening on your lawn there's no need to panic. While this picture appears to show dead grass this lawn is very much alive. It's in a "dormant" state, otherwise known as survival mode. What dormancy means is that as a plant system, water supply to the grass blade is basically blocked to preserve moisture in the roots, which is the heart and soul of a grass plant. The big question here is, how long long can the grass survive in a dormant state? The answer depends on a lot of different variables such as: temperature, sun exposure, etc... However, as a general rule of thumb, most lawns can survive 4-5 weeks in a state of dormancy. Beyond 5 weeks. with out water, many grass types will start to die off. WEED CONTROL While the main objective is to have a lush, health green lawn many customers will judge the success of a lawn care program on the presence of weeds. Hot and dry conditions can create a temporary conundrum for controlling weeds. Although they won't permanently damage the grass, weed control products can be quite hard on a lawn when it is drought stressed. For those with pesticide bans/restrictions, this challenge is further exacerbated by the use of chelated iron based weed control; Which can temporarily blacken the grass. For these reasons, your lawn care professional may either suspend any planned weed control applications or they will spot treat only the areas that have weeds, to minimize additional stress to the lawn. WATERING For homeowners, watering the lawn in summer drought conditions can be expensive or even illegal, depending on local watering restrictions. However, it is important to note that a deep watering can prolong the "survival mode" and help to save the grass. The following information about watering assumes the ability to water the lawn on a regular basis. Grass plants are essentially 90% water and therefore needs regular waterings either from rainfall or by irrigation. Specifically, grass needs 1-1.5 inches (3-4 centimeters) of water weekly. In general your watering schedule should be based on deep and infrequent waterings. It should also be flexible with current weather conditions. Under normal conditions watering should always be done early in the morning. Evening watering can promote the spread of disease because the leaf blades of the grass stay wet for prolonged periods. Disease potential increases with the frequency of evening watering. That said, if your lawn is drought stressed water it whenever you can. Typically, Mother Nature supplies the required amount of moisture during cooler times of the season. The goal of your watering should be to replace what rainfall does not supply, usually during these hot summer months. Heavy downpours, common at this time of year, may appear to provide relief for your lawn. However, if the lawn is droughted and the soil is hard and compacted, these flash flood storms may not penertrate the soils and.or the root system. This type of rainfall will produce standing water may be required. When considering water requirements for a lawn there are three basic things to consider up front:
- Soil Type (clay or sand)
- Grass Type (sun or shade)
- Physical Characteristics (such as sun exposure, surrounding trees and shrubs, hills, sloped areas and use patterns with children, dogs, etc...
The type of grass you have, and the soil under it, sets the stage for what type of a lawn you will have and the problems you may face. You may have a recurring problem on your lawn every year where a certain area turns brown. Sometimes planting a different grass type more suitable to that particular area can solve the problem. Your local Weed Man can help with proper seed selection if this is that case. In terms of watering, think of your soil in two extremes. If your soil is more clay-based it will act like a sponge in wet/rainy conditions, or like pavement in the summer heat. Sandy soils, regardless of the time of year, act more like a strainer when it comes to water.
In hot dry conditions clay soils become rock hard, to the point where water cannot penetrate them. In this case the soil acts more like pavement. Rather than absorbing the water it cracks and heaves in hot weather. Clay soils present a considerable challenge in drought conditions. Hard, compacted clay soil that is in drought will restrict root development and nutrient exchange. This hardening shuts the grass down as a plant system and the lawn goes dormant.
Watering a lawn growing in clay soil can be very frustrating, particularly on sloped areas. If you have a sloped area where the water tends to roll off rather than infiltrate into the soil. there are a couple of things you can try. One, rather than using a sprinkler try using a soaker hose, or some watering device that minimizes the size of the water droplets. This will help cut down on the roll off. Another method that helps is prodding that area with a pitchfork or some tool that will create a series of holes that the water can enter. This is almost like a homemade aeration.
In general lawns with clay soils need to be aerated at least once per season. Aerating is especially important if your lawn is a high traffic area (kids, pets, etc...). Over-seeding at the time of aerating is also highly recommended.
Lawns growing in sandy soils can prove to be extremely challenging throughout summer drought periods. In a perfect world every homeowner would water the precise amount of water the lawn needs in the morning only. Unless equipped with a programmable irrigation system most homeowners are pressed for time and cannot sustain the "perfect" watering schedule. When the weather becomes hot and dry, like it is now, the first lawns to start turning brown are those with sandy soil areas. When these extreme weather conditions persist, homeowners should water whenever they have the opportunity. It is important to ensure that the maximum amount of water (1.5 inches or 4 centimeters) is delivered to sandy soils during drought periods.
The main issue with sandy soils is their inability to retain moisture. Simple steps a homeowner can take such as mulching grass clippings as opposed to bagging and/or top dressing their lawns with triple mix soils will help with water retention.
MOWING Aside from a sound lawn care system of fertility and weed management, how your grass is mowed is probably the greatest influential impact on the appearance of your lawn. We have covered a lot of ground on proper mowing in previous posts, but here are the basics:
- Never mow more than 1/2 of the grass blade at a time. Mowing 1/2 or more of the blade removes too much of the plant at one time, which will 'scalp' the lawn and perhaps leave heavy clippings that will smother and possibly further burn the grass.
- Always mow with a razor sharp blade. Lawn mower blades need to be sharpened 2-3 times during the lawn care season. Mowing with a dull blade rips/tears grass blades causing plant injury that results in a general yellow, unhealthy appearance. New lawn mowers need to have blades sharpened because most manufacturers do not fully sharpen blads for shipping purposes. Keep two blades on-hand so you always have a sharp blade to swap out.
- Alternate mowing directions. By altering the mowing directions you keep the grass growing straight up. Otherwise the grass would take on a slanted growth pattern; Creating many different problems, including proper air and light circulation which are important for optimal turf health.
- Mulch Clippings. If you are mowing often enough to follow the 1/3 rule above, you will never have to worry about the clippings smothering the lawn. Most lawn mowers are able to mulch light clippings quite easily. Grass clippings are a great natural source of nitrogen that should really not be removed by bagging.
At this time of year, and particularly in hot dry regions where lawns are showing obvious drought stress, mowing should be suspended altogether. In fact, particularly if you are restricted from watering, it is a good idea to minimize all foot traffic on a dormant lawn. Normal mowing practices can resume when the weather cools down and the lawn starts to grow more actively. So, if your lawn is showing signs of drought, please remember it is natural for your lawn to brown. Adjusting weed control strategies, watering and mowing & reducing foot traffic and general activities on the lawn, may be necessary to get your lawn through a hot and dry stretch of weather. Summer conditions can also contribute to turf disease and insect issues. If the brown spots you see seem to be rapidly increasing by day, rather than gradually like drought symptoms, please contact your local Weed Man to do a complimentary analysis.