Landscaping Basics: Water and Native Plants

When I took a Master Gardeners class several years ago at UDC (I don’t consider myself by any standard a “Master Gardener” but it was a great class!), I vividly remember one lecturer asking the class:

“What is the most important factor when planning your garden?”

There were a lot of excellent guesses from the seasoned gardeners:

“Soil composition?”

“No.”

“USDA zone?”

“No.”

“Amount of sunlight?”

“No.”

No one came up with the right answer.  Finally, the lecturer, who was some sort of farmer or commercial grower, looked at us all in exasperation.  The right answer?

“Average annual rainfall.”

Water!  It is critical for life for humans but especially so for plants.  About 90% of a plant is composed of water.  The number one reason houseplants die, for example, is due to watering problems–either watering too much or watering too little.

Today’s post is about organizing the watering aspect of your garden maintenance.

1.   Working with Your Rainfall

Rain is wonderful.  You can save yourself a lot of time and effort if you allow the rain to do most of your watering for you. You will also save money on your water bill and do the earth a favor as well.

What is the average annual rainfall in your area?  It isn’t all that easy to find.  You can Google your city and state along with the words “average annual rainfall” and generally you will come up with at least something to give you a ballpark estimate.

Dan Baker has ranked all 50 states from wettest to driest and has compiled data on weather extremes.  The wettest city in the United States is Hilo, Hawaii where it rains approximately 277 days out of every year with average annual precipitation of 128 inches.  The driest city in the United States is Yuma, Arizona, where it rains approximately 17 days out of the year with average annual precipitation of  just 2.65 inches.

Generally, the wettest cities are on the east and especially southeast of the United States and the weather gets drier as you head west.  How Stuff Works has a great map showing U.S. rainfall too.

I currently reside in Virginia, the 19th wettest state with average annual precipitation of about 44 inches but grew up in Utah, the second driest state, with average annual precipitation just over 12 inches.  When we first moved to the DC area, it was shocking to learn that almost no one has sprinklers installed in their lawn here.  The rain provides sufficient water for lawns and trees and it is very rare to see anyone out watering with a hose.  In Utah, almost everyone had sprinklers running generally twice a day in the summer and almost every year there were warnings about droughts and water shortages.

2.   Use Sprinklers and Hoses Wisely

If you require additional water for the plants in your garden, most often sprinklers or hoses are used.  C. Colston Burrell for TLC suggests that you install rain gauges in your landscaping to determine how much water your plants are getting.  If you are getting less than about 1” per week, you need to provide your own watering to compensate.  When watering, you have to be careful that most of your water is directed at the soil and roots of the plant and not on the leaves and foliage.  Getting soil or water on the foliage causes an enormous amount of problems.  Soil can transmit various diseases to the plant and water on the leaves can result in either growth of molds or fungus or in some cases scorch marks from the sun.

So, if you are watering, generally early morning is considered the safest time as the plant foliage has time to dry out during the day.

In my own experiments with houseplants, I have found that underwatering is less of a sin than overwatering.  When a plant severely lacks water, its leaves droop in a cry for help.  Adding water usually quickly restores the plant to health.  I have never, however, been able to restore a plant suffering from overwatering.  The rot and damage to the root system is often hard to fix.  Generally, I test a houseplant for watering by just feeling the soil and watering when the soil is dry one knuckle deep.  I am not sure if you can so the same for garden plants.  Most people just seem to water on a schedule, regardless of whether the plant needs it or not.  Using a rain gauge or touching the soil might give better results.

3.   Select Plants that Work with Your Existing Water Supply

For decades, we have gotten used to planting whatever plants are available at our local nurseries or hardware stores.  Most people generally plant whatever looks attractive to them.  A movement is afoot, however, to encourage people to use native plants rather than exotic species.  The National Park Service indicates that nearly one quarter of the 20,000 native plants in the United States are at risk of extinction.  In part, the native plant movement is about preservation of our natural heritage but other benefits include:

• providing food and habitat for native wildlife
• slowing down the spread of fire by staying greener longer
• producing long root systems to hold soil in place

What plants are native to your area?  Again, Google is your friend here.  Many states have a “Native Plant Society” with great resources.  Here is a great brochure from the Virginia Department of Conservation and Recreation for the Piedmont district of Virginia.

My favorite Virginia native plant is the magnolia tree, Magnolia virginiana, which according to the U.S. Forest Service, “flourishes in moist, acid soil such as the swamps in the eastern U.S. and along stream banks.”

Contrast the magnolia with a native Utah plant, the sego lily, which prefers “a deep, sandy soil with good drainage.”

I confess I have not been on the lookout for native plants in my garden but I plan to do so in the future.  There are a lot of wonderful choices!  While they might not be available widely at local garden centers, many suppliers are available through the magic of the Internet.

Currently, our garden is full of plants that have survived in spite of severe neglect.  We don’t baby them with fertilizer or special watering.  What is here has adjusted to the natural conditions and comes back by itself year after year.  Of course, we have lost quite a few plants using this technique as well and we don’t have an award-winning garden either!

As we think about our future landscaping plans, we will be thinking a lot about native plants and water.  I hope it has given you some food for thought as well.

Do you have a watering tip or a favorite native plant?  Please share in the comments.