Chemicals are used in hot tubs to keep them safe, sanitary and clean for users. It is the chlorine, bromine and sodium carbonate (used to raise pH) that mainly affect plants. While too much exposure to the salt in these elements can kill plants over time, a little bit splashed here and there should not harm them. Plants that tolerate salt or have waxy leaves, such as wax myrtles, lantanas and beach morning glories, are less affected by the salts. Also, soak the soil with hose water every couple of weeks during times when your hot tub is used frequently to flush out the salts and minimize the damage, if any.
When the leaves begin to yellow, it is usually a sign of under- or over-watering. It can also be a sign of too much salt from the chemicals. If the yellow leaves are located mostly on the side of the hot tub where they are more likely to get splashed, then it may be the chlorine.
If your plants stop growing or grow slower than similar plants, it is usually a sign of lack of water or under-fertilization. It can also be a sign of too much salt from the chlorine.
Brown and Curled Leaves
When plant leaves begin to brown and curl, it is often a sign of over-watering. However, it also a sign of too much exposure to chlorine. Again, look at where the damaged leaves are located and if they are on the side facing the hot tub.
Lack of Blooming
Another chemical in a hot tub that can affect plant is sodium carbonate. Hot tubs have a pH level of 7.4. Some plants that are acid lovers, like azaleas, may not bloom or grow well near a hot tub. If the acid-loving plants nearest the hot tub are not thriving, test the soil’s pH level with a soil testing kit and add limestone according to package instructions to raise the acidity to the plant’s specific need.