As an experienced gardening and landscaping expert, I can confidently say that mulch can play a role in either preventing or facilitating the spread of ground cover plants. However, the effect of mulch on ground cover spreading depends on the specific type of ground cover and its method of spreading.
If the ground cover you are working with spreads through stolons or above-ground stems, such as some types of creeping thyme or ajuga, a heavy layer of mulch may hinder their ability to spread. In these cases, the mulch can act as a barrier, preventing the stolons or above-ground stems from rooting and establishing new growth. Therefore, it is advisable to apply a lighter layer of mulch in these situations, allowing the ground cover to continue spreading while still providing some weed suppression.
On the other hand, if the ground cover spreads through underground rhizomes, such as some varieties of creeping Jenny or mondo grass, mulch should not impede its spread. Rhizomes are underground stems that can grow horizontally and produce new shoots, enabling the ground cover to expand. The mulch layer will not prevent the rhizomes from spreading, as they can easily grow beneath the mulch and establish new growth. In this case, you can apply a thicker layer of mulch to effectively suppress weeds and provide a more substantial barrier.
It’s important to note that while mulch can help suppress weeds, it is not a foolproof method of weed control. Some persistent and aggressive weeds may still find their way through the mulch layer. Therefore, regular monitoring and manual weed removal may still be necessary, especially during the initial stages of ground cover establishment.
In my personal experience, I have worked with various ground cover plants and have seen the impact of mulch on their spreading habits. For instance, when planting creeping thyme as a ground cover, I applied a light layer of mulch to allow it to spread and fill in gaps between the plants. This approach helped to suppress weeds while still facilitating the natural growth and spreading habits of the ground cover.
To summarize, mulch can either prevent or facilitate the spread of ground cover plants, depending on the specific type of ground cover and its method of spreading. If the ground cover spreads through stolons or above-ground stems, a lighter layer of mulch is advised to allow for continued spreading. If the ground cover spreads through underground rhizomes, a thicker layer of mulch can be applied without hindering its spread. Regular monitoring and manual weed removal are still necessary to ensure the success of the ground cover and prevent weed competition.
