The Art of Proper Watering

All plants need water. Although some species are naturally drought tolerant once established, they all need to be properly hydrated in the first year or so after planting. When local gardeners reach out to us for plant problem diagnosis in the heat of summer, the issue is almost always due to improper watering. In order to look at a plant in decline and determine if that decline is due to a watering issue, it’s important to understand how exactly plants use water to function and grow.

Why is proper watering important?

Plants are made up almost entirely of water. Their cells are plumped by water molecules which allows the plant to stand upright and appear voluminous. The most obvious sign of water deficiency is a plant that looks droopy, deflated, or limp. Without enough hydration, collapse is imminent.

Water is essential for healthy plant functioning. Along with carbon dioxide and sunlight, water is one of the necessary ingredients for photosynthesis. Without a steady supply of water, plants can’t produce carbohydrates or oxygen. 

The vast majority of water taken up by plants is used for transpiration, which is the movement of water from the root system up to each leaf. Once water molecules reach the pores or ‘stomata’ in the foliage, they evaporate into the atmosphere which effectively cools the plant. Think of it like the plant version of sweating. As temperatures increase, plants need additional water to support the transpiration process and keep themselves cool. 

Transpiration also regulates the flow of nutrients throughout the plant. Essential chemicals in the soil like nitrogen, phosphorus, and potassium are carried by water up through the roots and replenish the rest of the plant. That’s why we always recommend deep watering at the time of fertilizer application.

How do I know if my plants need water?

Successful gardeners spend enough time around their plants to notice subtle changes. Like all gardening problems, watering issues are easiest to treat when they’re identified early. Water deficiency presents in many different ways across plant species and conditions. Yellowing leaves, limp foliage, and crisp leaf edges all seem like clear signs of a watering problem, but they can also indicate unrelated issues. Garden pests and disease can present with many of the same symptoms. Pay close attention to the appearance of your plants along with the growing conditions to determine if the decline is truly due to watering problems.

If your plant is showing signs of decline, the first step is to closely inspect it for harmful bugs, fungus, or other signs of disease. It’s important to rule out these issues before changing your watering routine.

Next, check the soil moisture about six inches below the surface – is it moist or dry? Properly watered plants should be in evenly moist soil that is neither too dry nor too wet; if the soil has a consistency more like mud, chances are the plant is receiving too much water. If you’ve watered within the last two to three days and the soil is dry, the plant likely needs more water.

Signs of Improper Watering

Yellowing Leaves

Yellowing foliage in the absence of pests and disease is a clear hint that something has gone wrong with your watering routine. Unfortunately, sometimes it’s a sign of overwatering and sometimes it’s a sign of underwatering. Look closely to determine where the plant is yellowing. 

If the plant is yellowing from the inside out or from the base of the plant upwards, it’s not taking in enough water. When plants are stressed, they’ll conserve resources by dropping old foliage to save water for the newest foliage. Yellowing foliage due to drought is often accompanied by leaf curling, limpness, or browning around the edges.

Limpness

Plants lose their rigidity when the cells collapse due to lack of water. Luckily, most plants bounce back after a deep watering. Missing one or two watering sessions and allowing a plant to collapse is okay, but repeated collapse leads to a decline in overall plant health. After many periods of drought, the plant may be unable to recover even after it’s given water. Try to water your plants before they show this obvious sign of drought.

Crisp, brown foliage

Dry, brown foliage is a clear signal that the plant needs either more water, less sun exposure, or both. More often than not, crispy brown leaves are due to an extended period of drought. Plants will conserve water for their newest foliage by allowing the oldest leaves near the center of the plant to die. Unfortunately, there is no way to revive the old foliage and we recommend removing all the damaged leaves.

How to Water Properly

There’s no standard recipe for plant maintenance. As growing conditions change and plants mature, the frequency and volume of water they need will vary. For newly installed trees and shrubs, we recommend watering 2-3 times a week and providing 3-5 gallons of water each time.

Each time a plant is watered, the soil should be repeatedly saturated. If you’re using a hose, drench the base of the plant for 10-15 seconds before moving on to the next plant. Then return back to the first plant and drench it for an additional 10-15 seconds. This method ensures water percolates down to the deepest roots.

When in doubt, it’s always best to check the soil moisture or reach out to a fellow gardener for advice. Luckily, watering issues are easily corrected with the right knowledge and a steady routine.