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Master Gardener's Gardening Guide

Winter Tree Care

Courtesy of Elizabeth Gardner January 2011

We all have a tendency to take a break from caring for our trees in winter. But while we may scale back on our tree work, there are still a few things we can - and should - do:

Winter Watering - All of our trees should be watered deeply once a month (this is especially important for fruit trees). The roots are still growing during winter, albeit more slowly, gaining strength for the big spring show. Water when the temperatures are above freezing (so the water can penetrate). Water where the water-absorbing roots are - at the dripline. Snow and winter rains are nice but they seldom are enough for our trees. For our friends who irrigate from an acequia, you have to cross your fingers and hope for a good sustained rain every now and then.

Mulching - Winter is a good time to refresh the mulch under your trees. Tree mulch should be two to four inches thick - but not deeper than four inches. Keep the mulch several inches away from the trunk as it will be a haven for insects and can cause rot at the trunk. It’s best to create a ringed barrier, to prevent the mulch from being washed back onto the trunk. Mulch to the dripline of your tree, where the hair-like, water-absorbing roots are located. A good mulch will help lessen the impact of temperature fluctuations in winter, just like it does in summer.

Dormant Spray - Dormant spray can be purchased at any garden center and most hardware stores. It is simply oil which you mix at a ratio of 5% oil to 95% water in your sprayer. When sprayed on the twigs, branches, trunks, and around the base of your trees, it acts to smother any over-wintering insect eggs present. Follow the directions on the label carefully.

As the name implies, it must be sprayed during the dormant season - before any new growth begins. Many people apply dormant spray only once, right before trees break dormancy (the best time). However, some believe it is beneficial to spray once mid-winter as well as late winter.

Once a tree has blossomed or leafed out, DO NOT use dormant spray. CAUTION - Do not use dormant spray on Blue Spruce; the oil of dormant spray dissolves the waxy needle coating which gives the Blue Spruce its blue hue. The wax will re-form and the tree will regain its blue coloring, but it may take a few years.

Finally, while the use of dormant spray is considered - and I believe is certified as - an organic practice, I have heard some question whether the dormant spray also smothers beneficial insect eggs. I have no data at this time to know whether or not beneficial insect eggs are present in the area and at the time of dormant oil spraying.

Pruning - Dead wood, suckers, and water sprouts can be pruned from trees any time of the year but most tree pruning is done in late winter. This is especially true for fruit trees, when pruning is usually aimed to occur just before the trees break dormancy - just before bud break. Depending upon where the trees are growing in Sandoval County, that can be anytime from mid-to-late February into March.

Fundamentally, trees are pruned for health and they greatly benefit from regular and proper pruning. While the art and science of pruning is a larger topic, here are a few guidelines:

  • On mature trees, limit your pruning to not more than 20% of the leaf canopy (the amount of leaf area);

  • Pruning of young trees (greater than two years old but still not nearing maturity) may be up to 25% of the leaf canopy;

  • When pruning a branch, either take off the branch completely or prune back to a lateral - a off-shoot of the branch you are pruning - that is at least one-third the diameter of the parent branch;

  • Never top a tree and do not leave stubs;

  • Most importantly, SAFETY FIRST. Pruning can be a hazardous job. Know your limitations. If you have a large tree which is beyond your skill level or physical capacity to prune, seek out a professional tree care company trained and equipped to handle large projects, preferably with an ISA Certified Arborist on staff but at a minimum, one that is licensed and insured.

Enjoy your winter trees!

December 2010

Thinking about next growing season . . .

Pruning is now the order of the month. Cut back perennials. Trim the hedges, shrubs, and trees. Remember sharp,clean cuts are the best. This adds shape to your plants, and in the case of the perennials reinvigorates them for good growth next season.

Take time to make a garden plan and look at catalogs for ideas and see what plants you might want to try. Check out the Gardening with the Master Program currently being held at the Meadowlark Senior Center. Call the Extension Office for topic and date and time. Phone # 867-2582.

November 2010

Don't forget to water during Winter!

We may have a dry winter this year so shurbs and trees will benefit from a good watering twice a month for the newly planted this year. Established shrubs and trees need one good soaking every month. Colorado State Extension says 5 gallons 2 times a month for the newly planted this year. Established shrubs less than 3 feet tall 5 gallons once a month. Over 6 feet tall need jumps to 18 gallons per month. Always apply water at the drip line.

October 2010

An Ounce of Prevention . . .

Now is the time to apply a pre-emergent herbicide, granular form, to the parking strips and landscape rock areas of your yard. Why, you ask? Because this product will prevent weed seeds that are there now and ones that arrive over the winter from germinating. I apply a pre-emergent herbicide in October and again in late February. This affords me help in the spring and summer. It means I only have to do weed picking 15 minutes every morning. See there is a method to the weed madness.

At this time I am also busy cleaning up raised beds, flower beds, & all areas where leaf litter appears. I section the entire landscape and do one section every week so it isn't overwhelming. I then give my trees and shrubs a good drink of water and lay down fresh mulch.

September 2010

Start your cool season vegetables from seed.

Replenish mulches.

Divide your iris, shasta daisies, gaillardias, day lillies, and reset into good soil full of organic matter and water well.

August 2010

Are you still weeding your 15 minutes every morning? Keep at it! The pay off is weed free spaces!

This month you are ready to trim off the faded flowers on crape myrtles. This will encourage a later bloom.

Check your irrigation system to make sure all is flowing well.

Prune out dead wood from trees and shrubs. Remember major pruning will happen much later after the frost.

Establish your new compost pile.

July 2010

Weed, Weed, Weed!!

What is a weed you might ask? A weed is plant that grows in a spot that you do not want it to grow. Example: A flower growing in your turf area, could be considered a weed.

Yes, folks it is time to really hit the weeds in your yard. I suggest 15 minutes every morning to stay on top of the weeds. Divide your yard into zones...say the four directions N-S-E-W, work your way around the house. Pick one direction N-S-E-or W each morning and do 15 minutes of weeding each morning. It may take you several mornings to get each direction finished, depending on how big your property is. But tackling weeds is all part of gardening.

Surprise Tip for this Month:

Remember to dead head flowering perennials. Otherwise you may have seeds from the perennials making weeds somewhere else in your garden!