While I was in a bit of a hurry Claire asked me, "Matt. How do I tell the person helping me water, how to do it?" And as if I queued Caitlin up, she lifted her head from our flower planting and responded "Oh! Watering may be the most complicated thing in gardening." And, perhaps more than anything in the garden, it is an intuitive art. Although I have some general guidelines I offer for instruction, because, well, I think, we live in a time where people need very specific operational guidelines that they can execute step by step - I would like to try and offer some bullet points with more theoretical flavor so you, the irrigator, can develop your own informed intuition.
1. Water moves through a plant, from soil to air. My language here will contradict the traditional teachings of this movement of water since the second I write "evapotranspiration" or "Hydraulic pressure" all will be lost to the reader. Imagine the air as a vacuum force of which its intensity to pull and suck water increases with heat, the drying effects of wind, and the decrease in humidity (or water already in the air). Water is in the soil and the plant is only the straw which the water is sucked though to be disturbed into the air as vapor. This suction pulls and pulls and pulls but when it gets hot and the soil starts to run out of water, you see what we all know as "WILTING." The vacuum pressure sucks the water out of the plant until it begins to collapse on itself. The fullness of the plant we consider normal and healthy is the plant filled with water. We call this state, or relationship of suppleness and full hydration, "turgidity" - or when the plant is full it is said to be "turgid."
2. A plant, as you know, will wilt. If you get water on it soon enough, within a short time the plant will perk back up and be refreshed. However, there is a term - "permanent wilting point." You can figure out for yourself what this means.
This being said, it is 90 degrees out. Don't finish reading this, get outside and water any newly planted flowers or plants before its too late.
3. When watering, one needs to insure the water gets into the soil, to where the roots are. Lightly spraying beds or planting areas with a spray nozzle in a situation like today (high heat) is ineffective as the water doesn't penetrate into the soil. The trick is to find the balance between that spray and a hose running at full flow. A spray distributes a small amount of water over a large area. An unchecked fully flowing hose may concentrate too much water in one place and simply run off without penetrating into the soil. This will also most likely erode your mulch.
Move forward in two directions - turn the water flow down to a point slow enough that it flows gravitationally down into the soil toward the roots of the plant. Secondly, you can increase the flow of water with techniques that distribute water over a small area so it can soak into the soil,
4. Different types of soil and mulches will allow water into them better or worse than others. Some will be more prone to erosion.
5. Don't think small. Think in terms of gallons of water. You need to direct gallons of water into plants and their root systems in order to have the water soak into a 4 to 12 inch depth.
6. Newly planted plants - which today is what I'm really concerned with, have very small and concentrated root masses. If you plant a #3 container shrub, all the roots are directly under the plant 9" either side of the center stem. To water (don't use sprinklers) outside of this space delivers no water to the plant.
7. There is this age old conversation and debate when horticulturists and gardeners want to sound smart and theoretical - "Should I water in the morning or evening." This distinction is totally irrelevant 99% of the time. Today, just water and water heavy.
Much of this debate has to do with managing moisture on the leaves of certain plants - like roses - that are susceptible to fungal development, as, like the tile in your shower, prolonged moisture on foliage can increase the risk of foliar (fungal) diseases. But, for the most part, we know what plants these are and we just try not to plant them because they make us need to debate when the best time to water is.
8. If you water manually with a hose as I have pictured and described, and avoid sprinkler and spray nozzles that cast water on foliage, you will avoid the problem of moisture on foliage.
9. In review, water needs to be in the soil so the warm air can suck it through the plant. If there is no water in the soil, the air sucks the plant dry until it implodes and dies. When you irrigate, get gallons of water deep into the soil.
10. Someday we may talk about how often. But, since I had to run out and water a bunch of wilting perennials and annuals I planted in the last five days, I thought I could share some thoughts on "Watering 911s."
***This being my longest post, it is dedicated to Ferncroft who, attacking my masculinity, claims my blog posts are always to short.
Landscape designer and Proprietor of Buffalo Horticulture