Depending on the maturity of a landscape, shade is an issue that may grow worse over time. Although low light can affect all plants, the most apparent changes will be in your turf. Below is a picture that I took a few years ago as part of my research that show just how drastic areas of shade can be on plant growth:
These four pots contain St. Augustinegrass, shown after a week of growth under 0, 30, 60, and 90% shade.
As mentioned in a previous post, the difference in growth is a result of signals to the plant to "grow out" of the stress (in this case shade). This can lead to thin, weak growth which may cause a decline in plant health over time.
If you do have shaded areas in your landscape, they may have to be managed a little different for success. These rules of thumb can help to keep these areas thriving:
- If shade is caused by plants (trees, etc), thinning of the canopy may increase available light. Care should be taken that pruning is not so drastic that it damages the tree (usually no more than 1/3 of the canopy should be removed).
- If possible, reducing traffic in these areas can prevent additional thinning due to stress and potential compaction.
- Increase mowing height to the maximum recommended for the plant. The more green, the more carbohydrates it can produce for survival.
- Try to reduce irrigation in these areas. As moisture tends to remain for longer periods, this will aid in reducing the potential for disease and additional stresses.
- It may be hard, but reducing fertilization (particularly nitrogen!) will help to reduce excess growth that isn't beneficial to the plant. Typically this should only be about 50-75% of what the rest of the lawn receives.
If the combination of these methods aren't working, a change in plant material may be necessary under dense shade conditions. A more shade-tolerant species may be the trick, especially if plant growth (and shade!) is expected to increase in the future.