Vented turf blankets go by different names in the industry; “growth covers” is perhaps the most common. Whatever we call them, they can be most valuable tools for any sports field manager trying to improve the performance and extend the playing season of their natural grass playing surfaces.
The better manufacturers can make vented turf blankets in almost any shape and size. They serve a variety of purposes for turfgrass and sports field managers, but all stem from warming the soil and grass canopy using sunlight and minimizing radiation heat loss at night. Turf blankets are used by field managers to warm all or part of the playing surface in an effort to extend growing seasons for natural grass surfaces.
They are also used to enhance seed germination and grass growth and development when normal climatic conditions would otherwise keep or put the turfgrass into a slowed state or dormancy. They are made of a lightweight, high-tech woven plastic material that can be installed with as few as 1-4 people in light wind conditions (depending on size of the cover) and 2-8 people in higher winds (10-15 mph), in my experience.
The result is a simple, easy tool for field managers to see sometimes dramatic results with proper use. Even if your current budget has little room this year, try getting a small, vented turf blanket that covers a critical, high-use area of your field, for example one soccer goal mouth. When the field stakeholders and decision-makers see the results, you will stand a better chance to fund more or larger covers as you may need.
Vented covers work the same reason your car heats up when you leave the windows up in the sun. A vented cover allows sunlight to pass through (translucence) to the surface. The surface (soil and grass in our example) is warmed by the sun, re-radiating longer wave infrared heat. Much of these heat waves are reflected by the cover material back down to the surface. In this way, the cover traps and builds heat energy underneath the cover. The result is the turfgrass growing in temperatures up to 35 degrees higher in certain situations than conditions outside the cover, in my experience.
Second, the vented turf blanket can trap and hold heat from escaping at night due to this shortwave/longwave “greenhouse effect.” Especially on cloudless, clear nights when temperatures can plummet, vented turf covers can hold in some of the trapped heat overnight. This may also help to minimize the potential for direct low temperature injury (DLTI) to the turfgrass.
Third, a vented turf blanket can minimize the chances of cool and cold season desiccation (drying out) of the turf and hold moisture in the seedbed for seeding and overseeding.
The vented design allows for gaseous exchange, getting needed oxygen to the turf and releasing built up carbon dioxide from respiration. The woven design also allows some heat out to minimize potential for high temperature stresses on the grass and even some injury in extreme cases. As such, vented turf blankets are not designed to be used in the hot months. Always monitor temperatures and conditions under your cover frequently. Temps can build up fairly rapidly in certain conditions.
Day length will affect the amount of warming, and the higher sun angles of spring and fall will intensify the heating compared to the lower sun angles of winter.
“Cheap is not less expensive” applies well to vented turf blankets. There is a lot of technology in the higher quality vented turf blankets that you don’t really notice, but these technologies make a huge difference in performance.
The quality of the material used to make the cover is key. Woven polyethylene fabrics are not a highly durable product. They may break down quickly from UV radiation in sunlight, especially in certain climates. The woven construction can come apart. Tears can keep going.
The better manufacturers have solved this issue with colored lace coatings, which not only add tremendous strength to the woven cover, it also allows the edges of the cover to remain free of sewn seams and grommets. The edges don’t fray and you can pin the covers down as tightly as needed, placing powder-coated pink pins wherever you need them, even out in the middle of the cover to baffle wind waves. If you happen to get a tear in the cover, it will not advance with this technology.
Another advantage of this technology is that it will allow you cut and fit your vented turf blanket to the specific shape of your field or area. Higher quality covers are also treated with a UV-resistant protectant to extend the life of the fabric of the covers.
Tips for using blankets
Vented turf blankets are a versatile turf management tool and can be used to achieve a variety of objectives. A few simple tips on their use and maintenance:
Make sure it is safe to push 6-inch pink anchor pins into your surface without hitting dangerous or damageable field components or underground elements.
Storage, deployment and uncovering: From my experience, it’s worth storing your vented turf blankets indoors to limit UV degradation and other forms of weathering. How you fold and store your cover(s) depends on your storage capacity and the size of the cover(s). Small covers can simply be unpinned and folded up by hand like a bed sheet. Large pieces, like part of a full-field turf blanket system, can still be folded, but the size and weight will require more people.
I have used two different ways to do this: Large area covers are typically folded in successive halves to create a long, skinny run of folded covers. From here the cover can be rolled up onto a large diameter tarp drum, maybe rolled onto one of the new custom lightweight inflatable drums or folded in successive halves lengthwise to create a square, folded cover on top of a solid-topped pallet. Each situation is different.
For breezy conditions, you can leave one edge pinned down as you fold in half a couple of times to fit your needs. This can also be done during a breezy deployment of the covers.
Always walk the edges and any other area where pink anchor pins were used during deployment to make certain none are left in the field.
In the mornings, covers can sometimes be wet and heavier from condensation under the cover under certain conditions. The covers dry quickly with a little sun or wind, making them lighter to handle.
Be sure to secure any field irrigation system before you deploy your field covers. You don’t want irrigation zones and heads popping up and washing out under the cover. You can however irrigate over the top off the cover with hoses and/or water cannons as needed.
In terms of maintenance, there is hardly any. The covers tend to be “self-cleaning” whenever you get a good rain or irrigation over the top. If, with a lot of use, the edges of your high-quality vented turf cover get a little beat up from constant pinning and unpinning, you can simply cut back an inch or so on the edges to get a clean start. You can’t do this with the less expensive imitations, and also why I don’t prefer grommets on my vented covers.
Ross Kurcab, CSFM, is president of the sports field/turfgrass consulting firm Championship Sports Turf Systems, LLC; Turf444@gmail.com and @NaturalGrassMan.