Many of us have a sinking feeling each fall as the beautiful lawn we’ve worked so hard on turns yellow. This seasonal change is simply a response to deteriorating growing conditions – it doesn’t mean your lawn is suffering. In this article, we’ll explain why grass turns yellow in winter and how you can maintain the looks and health of your lawn over the cold months.
Warm-weather grasses turn yellow as they enter dormancy each autumn. Chlorophyll production stops naturally as the days shorten and cold weather approaches. Limit traffic on a dormant lawn until it greens back up in the spring. Overseeding with cool-season grass can keep a dormant lawn green all winter.
Overview Of Why Grass Turns Yellow In Winter
Warmth-loving grasses stop growing and enter dormancy as a self-protective strategy to deal with winter’s cold temperatures and poor sunlight. The grass turns yellow in the process. If your lawn is composed of warm-weather grass, expect it to go dormant before cold weather sets in.
Interestingly, the grass isn’t really changing to a yellow color: the chlorophyll in the leaves is degrading as the plant shuts down for the year. The yellow tones left behind are the grass blade’s natural color.
Grass that looks yellow because of dormancy is still alive. Seasonal dormancy and the yellowing it brings aren’t unhealthy for these grasses.
Can Yellow Grass Turn Green Again?
Like any plant that’s gone dormant over the winter, your lawn will naturally return to its green glory in the spring. You’ll often notice the greening start up after a spring rain, but it can happen as soon as temperatures rise if the soil is moist.
If the weather is warming but the soil is dry, help the grass green up by giving your lawn a good soak. Check the weather beforehand: you don’t want to water just before an extended period of rain or a late freeze!
Know Your Grass Type
Two categories of grasses are suitable for lawns:
Cool-season grasses such as ryes, fescues, and Kentucky Bluegrass grow best in cool temperatures and weak winter sun.
Warm-season grasses that go dormant in winter include Bermuda, St. Augustine, Kikuyu, and Zoysia. They will turn green again with the arrival of longer, brighter, warmer days.
The Key Ingredient: Chlorophyll
It’s easy to forget how amazing it is that plants create physical material from sunlight. This process, photosynthesis, is powered by chlorophyll. One way or another, this vital compound helps create all the food we eat … and makes our lawns a gratifying green.
Chlorophyll is a complex pigment that works by absorbing light, mainly in the blue and red wavelengths: it reflects the green color we see. Chlorophyll also helps transmits energy throughout the plant.
The trouble is that it takes significant resources for grass to create chlorophyll … and it perishes quickly. Plants have to continually produce new chlorophyll to replace the old, and this can only work if there’s enough sun and warmth to sustain the process – which is why many grasses go dormant until suitable growing conditions return.
Dead or Dormant?
A dormant lawn turns yellow or brown, but so does grass killed by drought or another cause. How do you know the difference?
The fate of the grass lies in the vital crown where the roots and blades originate and are joined together. If the crown is damaged or dies, the grass cannot be revived.
Here are ways to tell whether your grass is dead or just dormant:
- If the entire lawn has turned the same color, it’s a good indication the grass is dormant. If only certain areas have turned yellow or brown, those patches are probably dead.
- Tug on a bit of grass: if it detaches easily from the earth, it’s probably dead and the roots have rotted away. Try a few different areas to make sure.
- It’s a sign the grass is dormant if only a few blades snap off when tugged.
- Check the roots: if the grass is dormant, its roots will be white and firm. Dead roots are dry, brittle, and gray.
Precautions To Take With A Dormant Lawn
There’s no doubt that winter can take a toll on your lawn. Even though grass goes dormant to protect itself, it’s still in a vulnerable state.
The following tips will help keep your lawn healthy and ready for spring.
Avoid Moisture Extremes
Dormant plants use much less water than when growing, so cut your normal watering routine down to about one 15-minute soak every two or three weeks. Take significant rainfall into account and only water when the ground is dry.
Though it is critical that your lawn’s roots never completely dry out, you don’t want to overwater, either. Dormant grass roots don’t absorb much moisture, and excess water promotes fungus and pathogens. Cold temperatures also slow evaporation and leaves the soil wet for a longer time.
Stay Off the Lawn!
Both for you and your lawn’s sake, try not to walk on your grass during winter.
Protecting Your Plant: Grass is vulnerable to being crushed or broken when dormant. The blades lack resilience and can’t repair an injury through new growth. Frozen lawns are especially brittle and easily damaged – a footstep can leave its impression in your lawn for many months.
Protecting Yourself: Frozen grass can be slippery and hide treacherous ice. Depending upon the temperature, a dormant lawn is often a muddy mess, too.
The fate of watching your emerald carpet become a forlorn stretch of yellow straw would be more acceptable if it offered a total break from maintenance—but no luck. Weeds don’t agree to fold up shop in cool weather: they keep growing and will seize the advantage over their sleeping foes (ie, your treasured grass).
So, plan to weed regularly. One consolation is that moist, cool soil makes it easier to pull weeds up by their roots, although this advantage goes away once the ground freezes.
You can get away with a few stray leaves on a summer lawn – but not a dormant one. Leaves, paper, and other material tends to pack down and cling to the ground in cool, wet weather: this not only suffocates the grass, it promotes rot and mold.
How To Maintain A Yellow Lawn
You can improve the health and appearance of your lawn despite its dormancy. There are three phases of care: preparation for the coming season, mid-winter maintenance, and helping the grass emerge from dormancy in the spring.
Preparing for Winter
Here are steps to take before winter sets in:
- Get your lawn into shape as it enters the fall! Cut it at the correct height and edge where needed.
- Wrap up your summer fertilization schedule before the grass starts to go dormant. Don’t fertilize after dormancy has set in.
- Weed and rake. You don’t want autumn leaves to remain on the grass.
- If you have construction or other work that will involve traffic on your lawn, try to get it done early enough in the year that the grass can recover.
- Fall is a great time to aerate your lawn. The process opens up the soil and allows it to adjust before a new growing season.
- Overseed your lawn to fill in thin or dead patches. The mild weather of autumn is ideal for grass seed germination—it’s much better than summer’s heat and intense sunlight.
Pro Tip: Overseeding after you’ve aerated is a perfect combination. Seed that falls in the holes left by aeration will be protected and germinate faster. Also, new roots establish themselves more easily in the softer earth. Raking the lawn with the back of the blade will push more seeds into the open holes.
Once your lawn goes dormant, it won’t need to be mowed or fertilized … but evergreen weeds still need to be removed. You don’t want your grass to wake up in a choking jungle.
Rake up stray leaves, sticks, and other material. Remember that dormant lawns are easily scuffed by hard traffic, and the damage will leave your lawn in catch-up mode next year.
Wake-up Call: Exiting Dormancy
For many of us, the first glorious sign of spring is seeing a light green cast coming over a previously yellow lawn. The color deepens daily as the lawn resumes growth, and the warm-season grass sown last year will grow in to erase those thin patches.
The main thing to do as warm weather approaches is to pay careful attention to soil moisture. Melting snow can keep the ground moist for weeks to come: it’s Nature’s way of helping new growth along. Follow this example and make sure the grass is well-hydrated as it emerges from winter.
How To Keep A Green Lawn All Winter
If you truly dislike the look of a yellow, dormant lawn, there are two basic approaches to keeping the grass looking green all winter.
Overseeding with Cool-season Grass
The most popular way to solve the problem of yellow lawns is to overseed it with a grass that stays green all winter. The underlying dormant lawn should be in good shape if you go this route, as the winter crop of grass will compete for soil nutrients.
Both annual and perennial ryegrass are commonly used. The idea is for the quick-sprouting rye to provide green vistas all winter, after which it will conveniently die away from mowing and the warm weather of spring.
Here are the steps to successfully overseed your lawn:
1. Plan to overseed a month before the expected first frost.
2. Before sowing, mow the lawn closely: typically about an inch and a half high, depending upon the grass variety. This is an ideal time to aerate the soil, too.
3. Clear all debris from the lawn before sowing.
4. Sow using from five to ten pounds of winter grass seed per 1000 square feet of lawn. More seed will make the lawn green faster, but a heavy stand of winter grass can complicate your lawn mix come next summer.
5. After sewing, apply a light feeding of starter fertilizer. This formula has extra phosphorus to help develop strong seedling roots. Note: Apply lightly to avoid damaging your dormant grass.
6. Over the winter, keep the cool-season grass cut from two to four inches high.
7. A few weeks before the last expected frost, mow down to about an inch high (or the minimum for your dormant grass). This shocks the winter grass and exposes the emerging warm-season lawn to more sunlight.
8. Don’t fertilize until the underlying dormant grass is at least halfway green again.
Coloring the Turf
Another way to keep your lawn green is to paint over the yellow grass. It won’t look exactly like your lush summertime lawn, though … and it’s messy and takes some effort.
To color your turf, you’ll need a garden sprayer. Other plants color up differently, so weed the lawn first. The paint job won’t damage your dormant grass.
Here are some tips:
- Select a color that isn’t too different than your natural green lawn. Tints are available from light green to olive to blue-green.
- Apply after your last mow of the season; you can color the turf anytime after your lawn has gone dormant.
- Clear leaves or other debris from the lawn first.
- Check the forecast to be sure it won’t rain or snow for at least eight hours after application.
- Wear clothing you don’t mind getting paint on.
- Begin by spraying the lawn’s edges carefully. Then work from the back of the lawn to the front to avoid stepping on wet paint.
- Spray using a circular motion to apply the colorant evenly.
- Be careful not to overspray onto sidewalks or other surfaces. It’s a good idea to mask off border edges. If you do overspray, clean the affected area immediately before the paint sets.
- Though most colorants dry in about an hour, allow double the drying time before walking on it. The coloring will last up to three months; reapply as needed.