Getting brown spots at tips of boxwoods after River rocks were pit around them. - Ask Extension
Hi Maryland Extension Center,
A landscaper suggested we put river rocks in the setting next to our house that have boxwoods planted in them. We ag...
Knowledgebase
Getting brown spots at tips of boxwoods after River rocks were pit around them. #877540
Asked July 16, 2024, 7:39 PM EDT
Hi Maryland Extension Center,
A landscaper suggested we put river rocks in the setting next to our house that have boxwoods planted in them. We agreed to this because they said it would help protect our home’s foundation from any future water damage (we actually asked for clay next to the house but they said it wasn’t available). Now our boxwoods are getting some brown areas in them. They landscaper put a fabric between the soil and the rocks to prevent weed growth. I tried watering the bushes the last couple of days to try to cool them down. Are our bushes going to die? How do we protect them? I’m wondering if the landscaper made a suggestion which was not best for either our bushes or our foundation. What should we put in that setting instead? Any information you can provide would be greatly appreciated.
Prince George's County Maryland
Expert Response
Can you share photos of the plant's symptoms? Leaf browning can have multiple causes.
While landscape fabric is often used underneath stone mulches (in part to keep the stones from gradually sinking into the soil), it will not prevent weed growth long-term. Organic matter like leaf debris which filters-down into the spaces between stones over time will allow weeds to germinate and root, and some roots may also be able to penetrate the weed barrier. If shrub roots growth through the barrier as well, in an attempt to get better oxygen levels near the soil surface, that entanglement can make it very difficult to remove the barrier later. For these and other reasons we don't recommend the use of landscape fabric for this purpose, and its presence also can get in the way of being able to monitor the plants for watering needs by feeling the soil about six inches deep in the root zone.
A mesh material like window screening (though perhaps coarser) could keep the stones at the surface while letting some of the finest organic matter debris sift-down into the soil, but as you might expect, it won't do much about weed prevention. Stone mulches don't break down into organic matter since they don't biodegrade, a potential detriment to plants they surround since that influx of organic matter over time can improve conditions in the root zone. Stone mulches, if used in sunny or semi-sunny locations, also absorb and retain/reflect heat, adding to the stress of the nearby plants during summer.
We're not sure what water damage the company was referring to when it comes to soil coverings near the building, but making sure downspout outlets are directed away from the foundation is one of the most practical approaches. Burying an extension pipe to move the outlet of a downspout further out into the yard can help with this, plus avoids depositing too much water (when it actually rains regularly) near plant roots, which could deprive them of oxygen and cause dieback. Some gardeners opt to avoid mulch next to the foundation if concerned about termites, but properly treated wood in the home's construction generally discourages this anyway, and all you'd need to do is make sure that mulch placed near the wall doesn't come into direct contact with exposed wood. Or, just leave a few inches of soil uncovered immediately next to the foundation itself.
An organic (biodegradable) type of mulch like bark, pine needles, wood chips, or leaf litter helps to keep the soil cooler than stone, is more "breathable," and is a way to add some organic matter (compost, essentially) to the soil as it breaks down and gets replenished. This organic matter helps the soil drain well, retain water when dry, retain nutrients, and feed the beneficial microbes that aid plant root growth.
Miri
While landscape fabric is often used underneath stone mulches (in part to keep the stones from gradually sinking into the soil), it will not prevent weed growth long-term. Organic matter like leaf debris which filters-down into the spaces between stones over time will allow weeds to germinate and root, and some roots may also be able to penetrate the weed barrier. If shrub roots growth through the barrier as well, in an attempt to get better oxygen levels near the soil surface, that entanglement can make it very difficult to remove the barrier later. For these and other reasons we don't recommend the use of landscape fabric for this purpose, and its presence also can get in the way of being able to monitor the plants for watering needs by feeling the soil about six inches deep in the root zone.
A mesh material like window screening (though perhaps coarser) could keep the stones at the surface while letting some of the finest organic matter debris sift-down into the soil, but as you might expect, it won't do much about weed prevention. Stone mulches don't break down into organic matter since they don't biodegrade, a potential detriment to plants they surround since that influx of organic matter over time can improve conditions in the root zone. Stone mulches, if used in sunny or semi-sunny locations, also absorb and retain/reflect heat, adding to the stress of the nearby plants during summer.
We're not sure what water damage the company was referring to when it comes to soil coverings near the building, but making sure downspout outlets are directed away from the foundation is one of the most practical approaches. Burying an extension pipe to move the outlet of a downspout further out into the yard can help with this, plus avoids depositing too much water (when it actually rains regularly) near plant roots, which could deprive them of oxygen and cause dieback. Some gardeners opt to avoid mulch next to the foundation if concerned about termites, but properly treated wood in the home's construction generally discourages this anyway, and all you'd need to do is make sure that mulch placed near the wall doesn't come into direct contact with exposed wood. Or, just leave a few inches of soil uncovered immediately next to the foundation itself.
An organic (biodegradable) type of mulch like bark, pine needles, wood chips, or leaf litter helps to keep the soil cooler than stone, is more "breathable," and is a way to add some organic matter (compost, essentially) to the soil as it breaks down and gets replenished. This organic matter helps the soil drain well, retain water when dry, retain nutrients, and feed the beneficial microbes that aid plant root growth.
Miri
