Trampolines are a key element in our Mission: Backyard Adventure.
If you’re looking at the impact that a trampoline will have on your grass, you are probably about to get a trampoline and wondering about the expected survival of your lawn. Or maybe you have a trampoline already, and wondering whether it is the trampoline causing the die-off underneath.
In general, trampolines kill grass. The trampoline mat prevents most of the necessary light and water getting through. However, there are some “shade” grasses that grow under a trampoline. If you have a very hot climate, you might find the grass grows better in the shade of the trampoline.
Let’s go through more of the detail below. If you’re still wondering about where to put the trampoline in the yard, you should check out this article I wrote to give you the 7 rules for perfect trampoline placement.
How Trampolines Kill Grass
With no light or low light, plants including grass, struggle to get the sun they need to photosynthesize. The weaker grass plants will die off, whilst the stronger ones will grow long, yellow and spindly as they strive to reach some light.
Trampoline mats used to be quite thick and blocked the light entirely. More recently, trampoline mats are made of polypropylene. Depending on the weave, will let some light through. In some cases, this can be sufficient to keep the grass alive.
Can Grass Grow Better Under A Trampoline?
In some cases, grass can grow better under a trampoline. For example, if you have a remarkably hot sunny yard, the trampoline will give the grass some respite from the sun.
If you have one of the nets that go around the base of the trampoline, like a skirt, you’ll find it will create a little greenhouse effect with even more shade, slightly higher humidity due to lower evaporation. This little greenhouse effect can encourage growth.
If this is the case, you may want to find grass that is better suited to your yard outside of the trampoline, and leave the existing conditions under the trampoline.
What To Do With Grass Under A Trampoline
In most cases, because of the filtered light and reduced water, the trampoline will cause the grass to die back. Be sure not to overfertilize. The grass isn’t dying from to a lack of nutrients, just lack of light. If you give it more lawn food, you may inadvertently over-saturate the soil with nutrients.
Do try to water more often. When the kids aren’t using the trampoline, put a sprinkler under the trampoline so that the water can reach the ground. When I first got our trampoline, I used to put the sprinkler to the side, and the water would land on the mat. And just like the rain, it didn’t get through evenly at all.
Watch that you don’t overdo it on the springs, as they might start to rust faster or the pad protecting the springs as this will go soggy or mildew faster.
You can also move the trampoline frequently, say every seven days. For this, you need to have a yard big enough to move it to three or four different locations. You want the lawn to have a couple of weeks to recover before rotating the trampoline back to it.
You can also seed additional low-light or shade-resistant grasses (see below). Just leave the ground as it is, wet it a little, and then throw some shade-resistant grass seeds over the top with a little topsoil. Remember not to over-fertilise.
How To Mow The Grass Under A Trampoline
Generally, grass that has been under a trampoline should be mown to a height at least ½“ higher than if it was just regular lawn.
There are two techniques to getting to the grass under a trampoline.
First Technique – The Contortionist. Depending on the size of your trampoline, getting a mower underneath can be tricky. You’ll only be able to push it in so far before the handle hits the side of the mat.
However, most lawn mowers have adjustable handles. These can go down to almost flat. You’ll be able to push the mower almost entirely under the 3ft height of the trampoline. I’ve called this The Contortionist move, as you will need to follow the trampoline under the trampoline to get to the center.
You’ll still need to get the grass around the legs of the trampoline. You can use hand clippers, or use a sacrificial string trimmer. The string may need to be replaced after hitting the legs many times.
Second Technique – The Strongman. If you are willing and able, you can probably pull and push the trampoline from its resting place. If the trampoline is 12ft wide and round, you’ll need to be able to move it 4 yards to get to all of the grass underneath. You’ll need to do this if your trampoline comes with a ‘skirt’ that prevents access to the underneath.
This technique has the advantage of being able to get to the grass that was growing around the legs without fiddling around. You’ll also be able to use a ride on mower or a push mower without having to adjust the handle angle.
Types Of Grass You Can Grow Under A Trampoline
There are a few grasses that have been developed for low-light or shady conditions. Most of these still need some filtered light that gives them 2-4 hours of sunlight per day.
| High Shade Grass | Perennial Ryegrass | Fine Fescue | Zoysia | St. Augustine |
|---|---|---|---|---|
| Season | Cool | Cool | Warm | Warm |
| Zones | Northern | Northern | Southern, Western | Southern, Western |
| Foot traffic | Excellent | Low traffic | Moderate | Moderate |
| Height | 1.5”-2.5” | 1.5”-2” | 1”-2.5” | 2”-3” |
| Water needs | High | Drought tolerant | Drought tolerant | Mid |
| Notes: | Can be patchy | Often included in a fescue mix | Turns brown in the winter | Not available AZ, CA, HI, NV, UT |
For cooler climates found in the north, you can try either Perennial Ryegrass or Fine Fescue. For warmer climates round in the southern or western zones, you can try either Zoysia or St. Augustine.
Cool Climate Low-Light Grasses
Perennial ryegrass is a cool season grass that is excellent with foot traffic. Whilst you can sow this under the trampoline, you also seed this around the trampoline or in other shady areas of your lawn where the kids play. You would plant this in either spring or fall. Shoots will appear with three days, and it is mowable in three weeks. It prefers soil pH 5.5 to 7.5.
There are two downsides to perennial ryegrass. The first is that it has higher water requirements than average. If it is subject to drought conditions, it will die off until the conditions improve. So you will need to proactively water under the trampoline. It also has a slight tendency to be patchy, as it only grows as a bunchgrass. It doesn’t have any spreading tendencies such as below-ground stems called rhizomes or above ground stems called stolones.
Fine fescue is another cool season grass. This type of grass is not really suitable for high traffic. This means you wouldn’t put it at the entrance to the trampoline. The upside is that it is drought tolerant, which means you can forget to water under the trampoline from time to time. It’s often found in blends with other fescues, and this would be fine to seed under the trampoline. It prefers pH 5.0-6.5, and to be given a small amount of nitrogen-rich fertilizer once a year to prevent the leaves from yellowing.
Warm Climate Low-Light Grasses
Zoysia is a warm season grass, that has the super-power combination of resisting drought and accepting a good amount of foot traffic. It is dormant in winter, so you only need to start mowing as spring comes. Zoysia can be kept fairly short, 1-1.5”, which is good if you live in an area with crawling things. This grass also prefers soil pH to be between 5.8-7.0.
The one downside of Zoysia is that it has a tendency to thatch. This is where small amounts of organic debris like grass clippings can build up. A small amount less than 0.5” thick is beneficial to the soil and roots, but when it gets over 1” thick, it can act as a barrier. The roots get starved of air, and water accumulates in the thatch without reaching the roots. You can get a dethatching rake if it’s not too bad, but it’s better to just remove the grass clippings as you go.
St Augustine is a warm season grass. It is thick and lush, and looks just gorgeous. It’s does take a bit of maintenance. This cultiva prefers to be kept longer, and is tolerant to grass clippings being left on the lawn. It grows best at a pH 6.0-6.5, and so you might want to add either lime or sulfur when you fertilize about three weeks after your first spring mow. St Augustine also likes an addition of iron in summer. It needs watering every week in summer, ideally in the morning before it gets too hot.
How To Care For Shade Tolerant Grass Under Your Trampoline
Remember, any shade-resistant grass still likes to have some light. You can probably have the equivalent of 2-5 hours per day if the light can filter through. I wouldn’t put the trampoline under already dense foliage from big shade trees. If it’s already difficult to grow grass under the shade, adding a trampoline will make it nigh on impossible.
When mowing, keep the grass under the trampoline ½“ to 1” longer than most of the grass in the lawn. This gives the grass more leaf surface area to catch the sun. When you do mow, try to alternate the directions. This encourages the blades to grow straight, which then gives more space for new blades. You end up with a thicker lawn.
Do be careful not to scalp the grass. This is the part of the grass plant that new leaves emerge from. Sometimes the plant can recover, but often not.
Don’t over-fertilize. Shady area grass needs half as much nitrogen as it grows slower. You may still have to fertilize once or twice a year with specific nutrients, but go easy on the dosage.
You may need to water more. Depending on the type of trampoline mat you have and how porous it is, it’s likely that there is less moisture getting through. If you already have a trampoline, try putting a sprinkler hose over the trampoline. Watch carefully to see where the drips come through.
You might find the lawn is getting worn near the base of the trampoline ladder with the kids coming and going. It can even start to wear a dip in the ground, as well as wear away the grass. You can put a couple of stepping stones leading to the base of the ladder to protect from this higher foot traffic.
Emergency Rescue Plan For Grass Under A Trampoline
Try Pennington’s One Step which repairs bare patches in 2 weeks or less. This comes in a dense shade version, designed for areas that receive only 2-4 hours of sunlight per day. It’s a mulch, seed and fertilizer all-in-one.
You can sprinkle it on the bare patch, and the new grass will germinate and sprout within 7-14 days.
The Grass Still Won’t Grow Under The Trampoline
You may need an intervention. The most frequent alternative it to consider mulch or tree bark. Take up the grass, or even just cover it with tree bark. If you use mulch, try to avoid including large numbers of seeds.
You can also turn it into a low-lying shady garden around the legs of the trampoline. Obviously, you won’t want to plant in the center where the trampoline mat will hit when the kids are bouncing. There are lots of shade resistant ground covers that can grow in low light conditions. Some have beautiful foliage and flowers. Consider some painted ferns, Pennsylvania sedge, ground-hugging periwinkle or hostas. Now it will be a thing of beauty.
In Summary
Grass that thrives throughout the rest of your lawn has quite different conditions under the trampoline. It won’t naturally do well, as it will get significantly less light and water through the mat. I hope this article has given you good ideas on how to successfully grow grass under the trampoline, rather than have your trampoline kill grass.
