Freezing Deserts – Watering the Desert Potted Garden When It’s Cold

Many desert dwellers will start complaining about the cold as soon as the mercury gets below 80°F! When we moved from an icy winter in New York State, we said that my blood thinned out as soon as we hit the Arizona state line. 😊   

However, for our potted desert gardens, the cold will affect them at different temperatures depending on their natural home. Bring tropical plants inside when the temps go below 50°F. Summer annuals can start their downhill trend after 45°F. The bulk of our potted spring, summer and fall plants might die when we hit the freezing mark of 32°F.  

Watering the Cold Desert Potted Garden

Newly installed plants  

Hopefully, you will have already planted your winter annuals and perennials before the first cold hits. However, we are sometimes surprised by an early dip in temperatures. If you hear a freeze warning is coming your way, quickly go to the section on Preparing for Freezing Temperatures.

With typical warm weather in the desert’s fall gardens, follow the tips I provide below.

Winter Watering in Desert Full Sun   

Newly Planted Annuals, Perennials and Shrubs  

During this startup period, you most likely will need to water every day. It is best to water in the morning before the heat of the day. Since the sun comes up later during the winter months, you won’t have to rush out in the winter as you would in the summer, but it is best to water early enough that the plants have a chance to dry some before the sun goes down.   

If the daytime temperatures get high (over 80°F), check to see that the pots did not dry out and supplement with another light watering if needed. You can do a visual check to see if they are wilting or stick your finger in the dirt and check for moistness. Newly planted annuals root systems are within the top 4 – 5 inches of soil, and you will be able to feel if they are still damp.  

Even during the startup period, if the days are chilly, you might only need to water your pots every other day. However, when you do so, be sure to inspect your plants the next morning to make sure none are wilting.  

I strongly urge new gardeners to purchase a water meter from the nursery, hardware or big box store. Use this to test yourself on what you think the pots need.   

To correctly use a moisture meter, place the probe into the soil at the depth of where you think most of the roots are located. New annuals, as I mentioned above will be about 4-5″ below the surface. A gallon plant will be about eight inches down and a five-gallon plant, 12-15″ below. The probe is only about 12″ long so that will be as far as you can measure. 

• While the probe is in the soil, look at the reading. You want it to be in the green moist area of the gauge.
• Take readings in various places of the potall areas are consistently moist.
• If the reading is anywhere in the red zone, give the plants additional water.
• If it is all the way to the bottom of the dry reading at #1, your soil is severely dry and you need to give them a long, slow soak. If the water runs right out of the drainage hole, get a bucket or watering can and add a drop of dish detergent to it and fill with water. This will help the soil be able to hold the water and rehydrate.
• Once you are done measuring the moisture levels of your pots, put the meter away in a dry, shady or enclosed spot. Do not leave it in the soil.  
  

Winter Watering for Established Annuals, Perennials and Shrubs  

Paying attention to overnight temperatures is critical when you are deciding how often to water. When the nights are cold, i.e., below 55°F, the soil has a chance to temper after the hot, direct sun has heated it. Therefore, after cold nights, plants in full sun might do just fine with a good soaking every other day.  

If some of your pots are in the afternoon shade, you might only need to water every three days. However, it does depend on the size of the container. Remember, I am talking about pots 22 inches and larger. For a review of my “rules” about pot sizes, follow this Link. 

To make your life easier, try to place your tender plants in groupings, making both covering and watering more efficient.   

Important: If your area has a forecast for freezing temperatures, be sure to water your ornamentals that day. The moisture will add heat to the plants and roots. Do not water cactus and succulents before a freeze.

Speaking of Cactus

The bottom line, most succulents and cacti do not need much water in the winter. When it is cold, they go into dormancy. It depends on the climate in your area.

Generally speaking, if it does not rain, you could water your potted succulents once a month. Then, use your moisture meter to see if they are dehydrated. You may be surprised by how wet they are!

Also, if you see the stems or leaves are wrinkled, that is a sign that they need a drink. But again, don’t water before a freeze!