It should go without saying that water is vital for plant survival. Plants use water for photosynthesis, the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.
Turgidity is the water pressure against the inside of a plant’s cell walls that keep plants
upright and supple. When a plant lacks water, decreased pressure causes the plant to wilt. During the spring, summer, and fall, wilted leaves are a good sign that the plant needs additional water. But during the winter, when many plants lose their leaves or wilting leaves are harder to recognize, how do gardeners know when to water?
South Carolina receives approximately 50 inches of rainfall annually, well above the country’s average of 30 inches per year. With enough rainfall, established plants need very little additional watering.
Newly planted trees and shrubs and periods of unusually dry winter weather are an exception to the rule. We plant trees and shrubs to take advantage of cooler temperatures in the fall, allowing plant roots to grow while above ground growth is dormant. The developing root systems of newly planted shrubs don’t get as much moisture as established plants. Therefore, it is necessary to monitor around their root balls carefully. During periods with no rain, check soil moisture weekly and water when the soil seems dry.
Plants in containers have limited soil volume from which to access water. Additionally, potting mixtures are porous and made to drain water quickly. It is crucial to monitor the moisture in containers throughout the winter to keep them from drying out. Use your fingers and eyes. Pull back the mulch, stick your finger in the soil, feel and look to see whether the soil is moist. If it is moist, there is no need to water. If it is dry, apply water when temperatures are above freezing.
If you water early in the day, the water you give your plants can actually be protective against nighttime freezes. The water in the soil acts as a trap for heat and helps the area around your plant stay a little bit warmer than the air as the night approaches.
Mulch is a great addition to your gardens. The two main types of mulch include Organic and Non-organic mulches. Organic mulches are good at keeping weed growth down and they add nutrients to the soil. Organic mulch includes wood chips, pine straw, lawn chippings, leaves and evergreens are also useful when you’re trying to reduce watering requirements. However, they do require more maintenance than non-organic mulches. Non-organic mulches include gravel, pebble, stone chips, bark, shredded leaves, straw, hay bales, etc.
Some products only last about 6 weeks while others can last up to 2 years. In general, though, it takes approximately 3 – 4 seasons for most mulches to break down completely. As it starts to break down, it will also start to lose its effectiveness. It’s important to keep up with the maintenance of your mulch throughout the seasons.
Credit: N. Jordan Franklin, Consumer Horticulture Extension Agent, Clemson University