Fall and winter watering:  during drought

 

Limited summer rainfall and water restrictions can deplete subsurface soil moisture.  Upon digging, people may find little moisture at 8 to 12 inch depths where most tree roots are located.  Paying special attention to fall watering is important for trees to mature buds and enter dormancy in a healthy condition.  Consider tree watering in addition to whatever general landscape sprinkling local water restrictions allow in fall months.

Colorado horticulture experts recommend watering underneath the branches within the circle bounded by the drip line.  Water to a depth of 12 inches.  Trees should receive ten gallons per inch of trunk diameter measured at knee height.  This amount can be reduced by that supplied by general lawn watering or if rain or snow is received.  Water trees three times per month in September.  Cut back to one or two times per month from October through March, two times monthly for young trees and for evergreens.

Mulch within a circle bounded by the drip line to a depth of 4 inches allowing 6 inches of space between the mulch and tree trunk.  A mulch circle of any area will be beneficial whether it extends to the dripline or stops short of that.

Many water application methods can be used.  Consider soaker hoses, soil needles, or soft spray nozzles.  On hard or compacted soils, soak, wait and soak again to avoid water runoff.  Be especially careful with soil needles, also known as deep root feeders.  Some people insert these well below a 12 inch depth, placing water out of reach of tree roots.  Soil needles should be inserted at an angle to a depth of 6 to 8 inches.  Leave the needle in place for 3 to 5 minutes with water turned on low to moderate pressure.  Water the area under the branches in at least twelve sites for a medium sized or larger tree.  Disperse water sites evenly within the circle bounded by the dripline.  For new trees, water all four sites at least 3 feet from the trunk (stem).

In dry years, established shrubs will need additional amounts of winter watering.  Apply 5 gallons for a small shrub (less than 3 feet), and 18 gallons for a large shrub (more than 6 feet) on a monthly basis from October through March.  Newly planted shrubs will require more winter water, twice monthly using these same amounts at each watering.  Be sure to mulch shrubs to retain moisture.

 

 

 

Buying trees & shrubs

Choosing a tree or shrub from a nursery is an art and a science. Small trees and shrubs adapt quicker to planting than larger specimens, especially trees.

A healthy young tree has a main stem, or trunk, with bark that is undamaged and has not been pruned at the top. The trunk should thicken as it tapers toward the roots.

Branches should be evenly spaced about eight inches apart around the upper one-third to one-half of the trunk. Avoid trees with branches that have been pruned at the tips.

Trees and shrubs are sold from nurseries in various ways including bare root, container-grown, and balled and burlapped. Bare root trees and shrubs do not have soil around their roots and are usually less expensive than container grown or balled and burlapped plants. Bare root plants should be purchased and planted when the buds are dormant, usually in March or April.

Container-grown plants are ready to plant when their root systems are developed, and they are not placed on the market until then. Roots should be numerous and preferably not circling inside the container. These plants experience the least shock from transplanting.

Balled and burlapped trees and shrubs are dug either from a nursery field or from the wild. Those dug from the wild are called collected stock. Collected stock generally is less successful than nursery-grown stock because many roots are lost when trees are dug up from the wild. Balled and burlapped plants are only available for sale when they are ready to plant.

 

 

 

Fertilizing trees & shrubs

There are three common ways to fertilize woody plants.

Foliar fertilization, a water soluble fertilizer that is sprayed on the foliage, may help small woody plants, especially plants that aren't getting enough iron. Be careful not to burn the foliage of plants by applying too much or too strong a fertilizer. At best, the results of foliar fertilization are short lived and it is only marginally beneficial for larger trees.

A granular fertilizer may be spread on the soil underneath a tree or shrub. For established trees, spread the fertilizer 10 to 20 feet past the canopy of the plant. This method is the most effective in a bed without ground cover or grass.

Fertilizer may be applied below the soil surface, at and beyond the drip line, using a root feeder with a fertilizer attachment. Although this method requires the most work, it produces the best results.

For general fertilizing, use a complete fertilizer that has the approximate ratio of three parts nitrogen, one part phosphorus and one part potassium and does not contain herbicides.

For iron deficiencies use a chelated iron fertilizer. Chelates help keep iron from binding to soil particles for a period of time.

Fertilize before July or after the leaves have dropped in the fall so the plant is able to harden-off properly for the fall.

Over-fertilizing can severely damage or kill woody plants. Read manufacturer's instructions on the amount of fertilizer to use before beginning.