Knowledgebase
Moss in grass in Colorado; mulch vs compost to retain soil; discarding pine needles and branches #622490
Asked April 09, 2020, 4:07 AM EDT
Dear Ag extension.
I have a lot of questions = let me know if I should put them in separate emails!
- Moss in grass in Colorado! We have a section of lawn north of our house and frequently shaded by the house that has moss in the grass. I thought moss was unusual in the dry Colorado air, but the patches cover a roughly 8x9ft section, and the lawn is developing patches of dry earth between the grass as well. I would like to take out the lawn and plant native Colorado plants or perennials that do well in Colorado, but wanted to get your take on what would do well in such conditions, and how to go about converting the area from patches of dead grass to perennials.
- Could you advise on using mulch vs compost to retain soil moisture in Colorado? I am tired of maintaining wood chip mulch, which -I think and correct me if I am wrong - needs to be removed to add any soil amendments and then put back. I had read that you might as well use a compost that would do double duty for moisture retention and a soil aid, and wanted your take on whether or not that would be a good idea, and what you advise for mulching around irises, or a bed with a combination of perennial shasta daisies, catmint and bulbs.
- Soil recovery after 10 years of landscaping fabric/black plastic. The prior homeowners installed black plastic when planting pine trees around 2002-2004. I hate black plastic and we are now removing it and the trees are mature. The plastic is now buried under almost a foot of pine needles in places and black soil rich with earthworms, with a solid layer of clay below where the plastic was. A small number of surface roots are above the black plastic. How can we accelerate the rejuvenation of the soil now that the plastic is gone? We would like to plant shade tolerant ground cover below the trees where light is patchy. Should we turn the soil to combine the top layer with the clay? Should we just leave it?
- Best way to discarding pine needles and branches? From the above pine trees on our property (blue spruce, ponderosa, and several long needle varieties) we have dense layers of pine needles. We cleaned the surface of the pine needles to reduce potential fire hazard, in the part of our yard that we have a grill, but there are 5-15 years of needles built up, which are turning into a nice humus layer. Could you advise on how much to remove to avoid a fire hazard but keep the nice humus layer, and what do we do with the pine needles? We have read that they shouldn't be composted so we are currently putting them in the trash, which seems ecologically like a bad idea. What are our alternatives for reducing fire hazard of pine needles waste? We have heard of using the dry long pine needles as mulch in other areas, but want your advice. Thanks!
Thanks for everything that you do! I understand you are volunteers and appreciate your time!
Best
Jeannie
Arapahoe County Colorado
Expert Response
For future reference, questions would be best submitted individually so they can be routed to the appropriate expert in that specific area.
1. Moss does occasionally grow in Colorado, generally in lawns on the north side of homes or in shade, particularly if there is abundant moisture. It does not grow in hot, dry and sunny locations. CSU has a great Fact Sheet on retrofitting the yard (taking out turfgrass and replacing it with something else).
https://extension.colostate.edu/topic-areas/yard-garden/xeriscaping-retrofit-your-yard-7-234/
Here is a great publication on native plants and groundcovers to replace turf:
https://extension.colostate.edu/docs/pubs/native/FrontRange.pdf
2. Compost as a soil amendment (organic matter), is dug into the soil, although it can be used as mulch on the surface of the soil. If you want to add additional amendments, then you would need to pull the wood chip mulch away from the base of the plant and dig the amendment into the soil. But wood chip mulch is very good for the soil as it breaks down. What kind of mulch is used is purely personal preference, but organic mulches (wood chip, compost, grass clippings, etc.) will feed the soil. Any organic mulch that feeds the soil will have to be replaced because of decomposition. CSU has a Fact Sheet on mulch with advantages and disadvantages of all types, and a Fact Sheet on soil amendments.
https://extension.colostate.edu/topic-areas/yard-garden/mulches-for-home-grounds-7-214/
https://extension.colostate.edu/docs/pubs/garden/07235.pdf
3. Black plastic is impermeable therefore no oxygen exchange can occur in the soil. Lack of oxygen to the roots significantly reduces plant growth. Black plastic also prevents water penetration. They likely used the black plastic as a weed barrier. Remove the black plastic but do not do anything with the exposed roots, and do not turn over or amend the soil. The majority of tree roots are in the top 12" of the soil, so turning over the soil with an amendment will damage these roots. After removing the plastic, replace with just several inches (not a foot) of the pine needles or wood chip mulch. These are both organic and will break down over time and feed the soil. You can plant shade tolerant ground cover but again, you will be disturbing the roots. So, plant the smallest containers of plants to minimize disturbing the tree roots, and you can put a small amount of compost in the planting hole. CSU Fact Sheet on groundcovers:
https://extension.colostate.edu/docs/pubs/garden/07400.pdf
4. Pine needles are a great mulch and protect the root system from the tree from which they came from. They are also a great mulch in perennial beds. Some homeowners compost them. However, decomposition of pine needles takes a long time as they have a waxy coating, but if you run them through a shredder or mower with a bag attachment, the smaller particles break down quicker. When mulching with pine needles, use just a couple of inches. As far as fire hazard, the following CSU Fact Sheet has good information on creating defensible space between fire hazards and your home. If pine needles are used as mulch in an urban irrigated landscape, the fire hazard would be less. You can bag excess pine needles and advertise to get rid of them. Many homeowners would gladly accept them to use as mulch in their landscapes.
https://extension.colostate.edu/topic-areas/natural-resources/fire-resistant-landscaping-6-303/
