“By far the best proof is experience.” ~ Sir Francis Bacon
There is no substitute for experience.
I worked on my first paver patio in the summer of 1988. The commonly accepted school of thought at the time was that a properly installed paver patio or sidewalk was virtually maintenance free. Paving stones are set on a minimum of 4” of compacted crushed limestone and a 1” bedding layer of coarse sand, with sand swept into the top joints. Weeds are definitely not coming up from below, but contrary to the early literature, experience has taught us that weed seeds will germinate in the sand-filled joints. Patio owners faced with this problem are often over-whelmed by the concept of spending a day on hands and knees physically pulling each individual weed. As organic gardeners we will not even consider spraying some poisonous herbicide on a surface where we serve meals and our children play.
Within the last decade, there has been a new product introduced that will eliminate most, if not all, of the weed growth and the ant activity that occurs in paver joints. The product is “polymeric sand” and goes by many different brand names. It is basically a silica sand with a bonding agent that causes it to set up “rubbery hard”. This maintains the patio’s ability to flex with the freeze and thaw and not crack and break like concrete or mortar. It can be applied at the time of installation, but today we are discussing the existing patio that is filled with weeds. To rejuvenate an old, weed-infested patio:
1) Pull or cut any existing weed growth. Depending on the species of weed and the extent of the growth, the best bet is usually to use a string trimmer to cut the weeds off close to the paver surface and sweep up all of the debris. The weeds that take root in tiny joints usually tend to be toughest to pull!
2) With a good quality pressure washer and the narrowest stream nozzle available, carefully, patiently, even painstakingly wash out every joint in the patio. You hope to remove the weed roots as well as silt and sediment that has built up in the joint. At the same time clean the surface of all of the pavers.
3) Allow the surface to thoroughly dry. I recommend 24 hours if possible.
4) We do not proceed with this step unless the pavers are completely dry, the air temperature is above 45 degrees and there is less than a 40 percent chance of rain. Apply the polymeric sand and sweep thoroughly into all joints.
5) Use a leaf blower on a very low or idle setting and remove any dry product from the surface of the pavers. This is very important, because any sand left on the surface will stick to the surface when moistened.
6) Moisten the sand in the joints with a light mist. This is best done in several stages: wet the product, let it absorb for a few seconds, repeat. There should never be pooling of water on the pavers.
7) Stay off of the patio for as close to 24 hours a possible to let the product cure.
The result is a bright, clean patio that looks like new and should stay that way for years to come. In even more recent years, there has been a product introduced to apply to even larger joints, such as those that occur with a natural flagstone or Pennsylvania Bluestone patios. The one we use is called “gator dust” and I think the results are even better than the polymeric sand. It can also be used at the time of installation or applied later with the steps outlined above.
If you have experienced weeds in your paver or flagstone patio and did not know where to start, please contact the landscaping department at Marvin’s Organic Gardens to discuss this issue or set up a time for someone to come out to your home.