Water cleans, cools, and feeds plants. Water transports the nutrients, assists in their use once inside the plant, and maintains the plant cells in working order. Water is absorbed by the roots and transported into the rest of the plant. Plants essentially drink water that has a little food in it. Plants lose water through transpiration. The water eventually passes out of the plant through tiny holes in the leaf surface called stomatas. Water pressure, filling each living plant cell, keeps the plant structurally rigid. This rigidity is called turgor pressure. When there isn’t enough water to maintain its internal water pressure, its turgor is lost, and the plant wilts, and eventually dies. Warm water is best for tropical plants. Cold water can stunt growth, put plants into shock, and even cause wilting.
What it does
Water cleans, cools, and feeds plants. Water transports the nutrients, assists in their use once inside the plant, and maintains the plant cells in working order. Water is absorbed by the roots and transported into the rest of the plant. Plants essentially drink water that has a little food in it. Plants lose water through transpiration. The water eventually passes out of the plant through tiny holes in the leaf surface called stomatas. Water pressure, filling each living plant cell, keeps the plant structurally rigid. This rigidity is called turgor pressure. When there isn’t enough water to maintain its internal water pressure, its turgor is lost, and the plant wilts, and eventually dies. Warm water is best for tropical plants. Cold water can stunt growth, put plants into shock, and even cause wilting.
Types of water
- Tap water- OKAY, but it contains chlorine and fluorine and not always neutral PH.
- Softened water- NO, high sodium, which, if it builds up in soil, It is toxic to roots
- Distilled water- EXCELLENT, but costly, no sodium build-up, no chlorine or fluorine
To fluorine sensitive plants (Dracaena, Marginata, palms, and Aglaonema), lime should be added, for fluorine accumulates around leaf edges, and turns them brown. For chlorine sensitive plants, let water set overnight to settle chlorine, where practical.
How water moves in soil
When water is added to soil, it moves between the pores and soil particles (more rapidly in sand, slower in clay). When the soil has reached is maximum amount of water it can hold, this is called field capacity. The soil saturates as the air pores fill, and moves down in the soil due to gravity. It cannot continue to filter down unless the soil level above it is saturated. This is called the wetting front. For example, you might add a quart of water to a 16” pot and the top 2 inches is wet, but the lower 14” is dry. The soil at the roots will not be wet until you add enough water to penetrate below this top 2 inches. The soil will also appear to be moist but the roots are very dry, SO WHEN IN DOUBT, CHECK WITH YOUR SOIL PROBE.
As a plant’s roots absorb moisture (and lose water via transpiration), soil wicks water down via osmosis and actually dries out from the top of the pot. That is why we check the top few inches to determine the moisture level. Water is also lost from the top of the soil through evaporation into the air.
Watering Guidelines
Watering is the most important skill of the technician and has a dramatic impact on the health and vigor of plants.
WHAT SHOULD YOU ASSESS TO DECIDE HOW MUCH WATER TO ADD TO A PLANT?
- Current moisture in soil
- Container size
- Light
- All the other water uses factors (see next section)
DRY SOIL: If the soil is dry, the plant obviously needs water, so add approximate the amount shown on the watering guide (e.g., 1/2- 1 gallon for 12” plant).
MEDIUM MOISTURE: This is where your understanding of the factors in water use is critical. For plants in high light, you should definitely water the plant. But for plants in medium or low light, water if there are multiple factors that indicate more frequent water. If many factors indicate less frequent water, then wait until next week. For small pots or biweekly service, water these plants even if moist.
MOIST SOIL: If soil is moist even on the surface, you would not water unless a water lover, in high light, or another high-water frequency reason. Then add a moderate amount (maybe half the recommended amount).
If a plant is repeated bone dry from week to week, and you have tested that you are watering to the bottom of the pot, then it may need to be pruned, repotted or moved to lower light.
Since service deals with many PLANTS IN LOWER LIGHT CONDITIONS, remember these plants will need to dry out more than plants in high light do. Plants in low light should have the soil almost dried out between waterings, which could take 4-5 weeks in marginal environments.
OVER-WATERING is not too a problem because of too much water, but too little oxygen. Air is vital to root growth and the activity of beneficial root organisms. If soil is kept constantly saturated, air is driven out, roots rot, and the rest of the plant dies from lack of nourishment from below.
The primary symptom of UNDER-WATERING is wilting leaves, beginning with the youngest. Older leaves do not show effects for a few days, then the edges turn brown. If completely wilted, put plants in a sink filled with water or clear plastic bag to restore turgidity.
AVERAGE WATERING GUIDELINES (AS NEEDED)
| Pot Size | Amount of Water |
| 9″ | 1/4 to 1/2 Gallon |
| 12″ | 1/2 to 1 Gallon |
| 14″ | 1-2 Gallons |
| 16″ | 2-3 Gallons |
| 20″ | 3-5 Gallons |