Protecting the Soil After a Fresh Planting
One of the most exciting times in a landscape installation is the moment the plants start to go in. At this point, the final grade and topography have been set and hard edges begin to soften with lush plants filling in a space. The last thing you want to look at is mud or weeds, so the next step would be to place some type of cover over all of the exposed soil around your new plants. Try to leave bare soil around newly planted plants invites a host of weeds and other plants to take over your newly planted space. There are many options in the marketplace for the best “material(s)” for protecting soil against weeds and improving overall plant health. A great question we ask ourselves is, “What will keep my plants alive and healthy?”
Let’s first examine the use of plastic and rock. Black plastic is great to use as an environmentally friendly way to kill off plants through a process of solarization. By covering plants for an entire growing season, the plastic will heat up and in essence, smother the plants under it. This works great if the plastic does not get punctured and is secured firmly. Other than smothering through lack of air, there is also limited moisture. As rain falls it will run off and not aid in helping any of those unwanted plants under the plastic. The combination of plastic with rock, whether it is white rock, river rock, pebbles, etc. is a tough combination for a long-term landscape. Initially the landscape may appear to meet your design goals, but over time you will find maintenance and general garden tasks difficult. One misconception is that weeds will not grow with plastic or rock present. Rocks, sticks, animals, etc. can easily puncture the plastic and once that happens there is plenty of space for many weeds to start to grow. Rocks are difficult to walk through when you are spending time in the garden and they are not welcoming at all when it comes to kneeling to weed or prune. Children also tend to enjoy playing with the rocks, which can lead to some tricky mowing.
Take this example. A client made the decision to purchase river rock and landscape fabric for their newly constructed landscape. The installation was completed in early July and they began to notice a few weeds starting to make an appearance about 6 weeks post-installation. The following Spring, the weeds had set in and it was difficult to keep up with them and pulling them was a challenge as they would break off at the base of the fabric and continue growing under the fabric and eventually back through. The swiftness of weed invasion resulted from river rock that was purchased at a cheap rate and was not cleaned before it was delivered. The extra organic matter mixed in with the rock increased the process of weed establishment. One-year post planting all of the rock and fabric was removed and it was replaced with mulch. A costly price to pay, but these clients saw a huge impact in overall plant health and ease of weeding as they wait for the plants to grow and fill in.
In the past it was very common to buy weed barrier fabric and put rock or mulch over top of that. The claims and advertisement regarding the fabric is up for debate. If fabric is placed over the soil, initially it will delay any weed growth from occurring. Eventually, leaves fall, dirt blows in and as these materials break down they create organic matter. This organic matter is prime growing ground for weed seeds to blow in and start to germinate.
Special consideration should be taken into account when using rocks as mulch. As the sun heats up the rocks throughout the day, this has a significant impact on plants and the environment that they are in. The result in more water usage and a warmer area that may create some shocking environments for certain plants.
As designers, we think about every aspect of the exterior of a site and how everything will fit together. With the addition of wood mulch in plant beds, it can be easily thought of as another piece of the drawing to add color. This is one area where we simply leave the natural state of the product and resist any urge to alter the original color. We advise against any dyed mulch. Many sources of dyed mulch use leftover construction debris that is extremely dry and can soak in the dyes better than hardwood mulch. Proper sourcing of the wood is crucial to ensure there is not treated wood being spread throughout your property from purchasing dyed mulch. A second reason is the increased maintenance requirement of dyed wood mulch. Through rain and intense sunlight the colors fade and what is left is less-than-desirable and therefore replacement or topdressing (thin layer over top) is needed.
Our planting designs involve determining the proper location and spacing of plants based on mature plant size. We recommend spacing plants in a manner that they overlap slightly once they are at their mature size. Once mature, it is not necessary to have a groundcover because eventually all of the ground will be covered in the new plants. This is not to say that weeding will cease, but it will be significantly less than other alternative cover methods. There are always animals out planting seeds and seeds blowing in and reaching the soil so maintenance is necessary, but reduced significantly.
Garden bed maintenance is a topic that is asked with each new project we are a part of and for good reason as it can be a time and money burden. We discuss maintenance up front with our clients to determine the best way to design planting beds throughout their property. There are ways to cut back on time spent maintaining and still create a specific look. If there is money allotted for outsourcing maintenance, we are happy to put together a maintenance care manual for horticulture specialists to use when working in your garden. There is not a landscape that is maintenance-free, but there can be low maintenance options. Often this requires some higher costs up-front, but you will experience lowers costs annually and a significant reduction in time spent maintaining your space.