The Good, the Bad and the Ugly Rules of Watering

Sacramento Tree Foundation

More than likely you’ve heard the term “green thumb”. Some people are said to have one and some do not. I like to believe that the term is synonymous with watering know-how and ability. One of the hardest skills in landscape to learn is how much to water and more often than not, I find that my clients love their plants too much rather than not enough. You’ve just spent a lot of money on plants and maybe your own back-breaking labor to install them.  It is an important concept to understand. I’ve struggled over my career to come up with the best watering instructions I can write. I believe over the last 7 years I have modified my instructions at least four times. Make them too simple and they are followed to closely, thus giving no wiggle room to the variance in plant requirements. Too complicated, and I instill fear in my client’s mind that they are not cut out for babysitting their new transplants every waking moment of the day.

Working in a nursery watering every day you get a feel for which plants are as I like to call them “the canary in the coal mine”. This is how I explain it to my clients. An Annabelle Hydrangea is one of the first to droop, sometimes years later during hot dry spells. It’s fine to let it get to this point, but make sure to water at this sign. Drying out a plant between watering is the best way to water. Think of what it means for the soil to be wet. It mean no oxygen for the roots, and rot will occur.

The best way to water is with a soaker hose, left at the base of a plant for deeper, more infrequent watering. Another option is for a hose to be left at the base at a “drip-drip” setting. The water should not be on high enough for the water to run off the plant, but soak in to the root ball. This is where many people go wrong. It takes a lot of time to move hoses around and to get a feel for which plants need more or less water. A quick soak means you will be back watering that plant in a day or a few days because it seems dry. It also means that the plant is being subjected to frequent watering that promote diseases and root rot.  Plants that receive water deep down in the soil are thus encouraged to reach their roots far and wide as it seeks water and to establish well. A secondary reason for watering the base of a plant is to keep water off the leaves, as will happen with overhead water systems.  This also promotes disease caused by fungus. In general, a perennial will need water 2-3 times per week while establishing and a tree or shrub will need 1-2 times per week for 30 min -1hr during the same time frame. Of course, a good rain negates the need for supplemental watering.

Other factors that play a role in watering can be types of soil, and age a type of the plant.  I have seen plants overwatered on a slope due to the heavily compacted clay soil that was used to make that slope.  This is one reason why newly constructed home sites are particularly hard on new plants.  Also, after a tree or shrub is established it might still be necessary to water once or twice during those hot mid summer months.  Certain perennials can dry out easier next to sidewalks and asphalt where the sun creates a hot surface that can burn and dry them out sooner.

Bart's Tree Service

Thinking a mild winter is good for your plants?  Not always.  I was reminded today of a sometimes forgotten principle.  Conifers…i.e.  a type of plants that is usually evergreen and has needles is green in the winter for a reason.  It doesn’t go dormant, and still moves water through its system, even in the frozen tundra of Chicagoland in February.  Usually they do this in the winter via snow coverage, but in year with little snow, and a ground that keeps pendulating between frozen and unfrozen, this can prove detrimental.  I encourage all my clients to water their new evergreens as late as possible.  A general rule of thumb is to give them a good soak right around Thanksgiving to allow them to begin winter on a well watered foot.  Many times in January, we get a week of warm up where the weather turns mild before plummeting to the sometimes single digits.  This is a good time to water again because the trees can dry out or desiccate.  In a case like this winter, several little warm ups can mean major water loss and new trees could benefit from watering every other week or so if the ground is not frozen.  Remember evergreens are one of the most touchy plants when it comes to overwatering and rarely recover once they show signs of it.  I was once explained this concept by one of the owners of Spring Bluff Nursery, Ken Norris.  I loved his stories to help illustrate his concepts because they helped clients remember them.  He used to say, remember that a person walking in the desert can be found in a day or so, dehydrated, but alive.  He’ll suffer, but will bounce back.  How long can a person survive at the bottom of a swimming pool?  A few minutes at most.

The kicker concept in the whole watering regime is that whether a plant is watered too much or too little, the signs look the same.  That’s when the questions must be asked.  Have we had adequate rain?  How often have I watered?  Does the ground around my plant feel moist?  Is there an underground sprinkler watering my lawn?  If there are droopy leaves, or leaves are turning brown and falling off the tendancy is to want to water more because the plant seems to be in distress.  If the signs point to plenty of water, then most likely it is an overwatering symptom.

Are you getting the picture.  Not an easy explained system.  After years of caring for plants, this becomes second nature.  Of all the possible negligence a person can bestow upon their landscape like lack of fertilizer, forgetting to weed, over or under pruning, or even improper lighting, it’s the most important to get the watering correct, or you have no need for performing the rest of the tasks. As I always tell my clients, if you have any questions about specific plants please let me know.  It is much easier than trying to revive a shriveled specimen of a formerly elegant plant.


2 thoughts on “The Good, the Bad and the Ugly Rules of Watering

  1. Thanks for the information. You answered a question I was just trying to figure out rgarding plants I am trying to keep alive inside this winter. Very much appreciate the sharing of your knowledge.

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