Greene Gardens

Garden Design and Maintenance for Denver

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Winter Watering Guidelines

With below normal precipitation for the month of January, and warm temperatures through the middle of February, it’s a good idea to give your trees and shrubs a drink.  Many areas are suffering from sparse snow cover, low soil moisture and low humidity.  Conditions like these can weaken or damage plant root systems.  Evergreens, south and west-facing lawns, plants near south and west-facing walls and newly installed plants are most susceptible to dry winter conditions.

To give your trees and shrubs a good start on the new growing season, use these guidelines:

  1. Water when air temps are above 40 F.
  2. Use a soil needle, deep root fork, sprinkler, or spray wand
  3. Apply water to many locations around the dripline
  4. Insert the fork or needle no deeper than 8″
  5. Apply 10 gallons of water per inch of tree trunk diameter measured at knee-height.
  6. Apply 5 gallons of water twice a month to newly planted shrubs
  7. Small established shrubs need 5 gallons per month
  8. Large shrubs (over 6 feet) need 18 gallons of water per month.

Your garden will thank you with a hydrated, healthy start to the season!

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Water, water, water

The forecast for the balance of January remains warm and dry. While this weather is great for the golfers who don’t need to fly to Phoenix for their fix, this forecast is not so great for our landscapes. Trees and other plants need moisture in the winter to prevent dessication, and root injury.

Check the soil around your newly planted and established trees. If a screwdriver or other probe, gently inserted around the dripline shows the soil is dry, it’s a good idea to provide the water that Mother Nature has not. CSU extension recommends about 10 gallons per-diameter-inch of the trunk measured at knee-height per month. If we don’t get a good snowfall, or that snow is very dry (as we have seen in January) supplemental watering is beneficial. Soaker hoses, a slow drip, or soft spray nozzles work best on hard or compacted soils to avoid runoff. Most roots are located with 12 inches of the soil surface, so be careful when using soil needles or deep root feeders that you do not insert the probe more than 12 inches into the soil.

It’s best to water at mid-day when air temperatures will exceed 40 degrees Farenheit. If using a hose at slow pressure, it may be hard to estimate how much water is delivered for a certain time period. Try this trick: set your hose at the desired slow rate – perhaps at 1/2 or 1/4 pressure. Measure the time it takes to fill 5-gallon home improvement store bucket. Double that time for 10 gallons. Let’s say it takes 5 minutes to fill the bucket. It will take 10 minutes for your hose at that pressure to deliver 10 gallons to the tree.

Now, if your tree is 2-inch diameter at knee height, it will need 20 gallons of water per watering. Therefore, you need 20 minutes of water at that pressure to deliver 20 gallons of water. Move the hose or the spray wand to several sites around the base of the tree within a circle bounded by the dripline.

This can be a slow process if you have several trees on your property. While watering, take the opportunity to really look at your landscape, and start making plans for the upcoming season. Want to add more flowers or shrubs? Have an area that you just don’t like? Observing your landscape in the winter is a great way to get a fresh perspective on problem areas. You’ll also benefit from some Vitamin D. Don’t forget to remove your hose from the spigot to prevent freezing.

If you just don’t have time to water, or physically have trouble dragging buckets, or hoses around, you can still protect your investment in your landscape. Several arborists and tree companies offer a winter watering service. Check with the ALCC (Associated Landscape Contractors of Colorado) www.alcc.com for a list of contractors qualified to perform this service in your neighborhood.

Come spring, your trees will thank you, and you’ll be happy that you protected these valuable specimens in your landscape.