That really shouldn’t be a question. Some popular counter arguments to mulching include. that the earth warms up more slowly and the mulch prevents water from evaporating. This would slow the growth of the plants. On the other hand, you could also say that mulch helps to conserve soil moisture, which is important during heat waves, or in regions where there is already a warm climate anyway. This in turn is good for the fight against drought. But the benefits of mulch go beyond just retaining moisture. That’s why we say: use mulch? Just do it!
The use of mulch keeps the soil temperature more or less moderate. Dr Linda Chalker-Scott recently proved this once again with a small experiment in which she measured the temperature in mulched and unmulled areas in her garden and surroundings with a soil thermometer. That experiment showed the following:
- Mulched raised beds have the most consistent temperatures.
- Unmulched bottom mounds have extreme changes, reflecting air temperatures.
- Bare soil in beds under sunny conditions have extreme changes reflecting air temperatures, but not as great as those in raised beds. They are hottest during the day and coldest at night.
- Bare soil in beds under shady conditions are the coldest soils during the day and even colder at night.
- Soil under living mulch (grass) and beds of varying depths of wood chips are cooler during the day than bare soil in sunny conditions, but warmer at night.
- Bare soil in beds that have just been mulched are much warmer than bare soils that are not near mulched areas.
- The soil temperature under grass or in beds at least partially mulched did not change overnight.
A study conducted by Dr Chalker-Schot in 2012 also showed that the temperature difference between a mulched and unmulled soil can be as much as 10°C. As you can see in the graph below, the soil temperature of an unmulled soil peaked around 38°C, while the temperature of a mulched soil with wood chips peaked around 28°C.
Protection for trees and shrubs
Probably one of the most underrated benefits of using mulch around trees is that it saves you from trimming or mowing the lawn around your trees. You can easily damage young trees if you touch the tree with your trim line too much. The nutrient ducts of a tree are located just below the bark. Mulch means you have to pull less weeds, so you can easily do some weeding around your trees before you start mowing the grass.