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Northwest: March/April Gardening

An Idaho Master Gardener shares tips and gardening news for early spring

A common question

When should I prune my roses?

Answer: When the forsythia blooms.

Recent gardening trends

The use of natives and drought-tolerant plants. In my landscape design business (, I find clients are surprised at the long list of drought-tolerant plants from which to choose. The advantages are not only reduced water needs, but the plants are more adapted to our alkaline soils.

Top to-do’s for March and April

  1. Rake and clean all gardens of weeds and debris (around the base of shrubs, etc).
  2. Prune (trees, shrubs, roses, and cut back all dead matter on perennials).
  3. Fertilize beds with a fertilizer formulated for garden beds (evenly numbered like 10-10-10 or 15-15-15 or similar) that includes iron, sulfur and other micronutrients.
  4. Spread agricultural sulfur (slow release pellets) that is good for our Idaho alkaline soils. It lowers the soil pH and makes existing nutrients in the soil more available to plants.
  5. Spread compost on all beds and rake with a garden rake to get the compost and fertilizer worked down through the bark mulch. Refresh mulch in areas where needed. The best mulch for our area is shredded bark. We have lots of wind in the Magic Valley (Twin Falls area) and the shredded bark mats down and doesn’t blow away.
  6. If we’ve had a dry winter and spring, be sure to water well—it’s especially critical for plants that are not well established (planted within the last year). We have an average of only 12 inches of rainfall in our area of Idaho (called a “high mountain desert”), so plants that are not native or drought tolerant need regular deep watering.

Favorite volunteer activities

Last summer we landscaped a group home for women recovering from addiction. The recovery organization moved a donated house onto a lot and we were challenged to meet the city requirements for landscaping. They had no budget, so all plant material and supplies were donated. I donated the landscape design and the Magic Valley Master Gardeners supplied the expertise as team leaders working with 75 volunteers (including families with young children). All trees and shrubs were planted in one day. It was extremely rewarding working with the volunteers, the staff and the residents to pull this project together.

Idaho gardeners’ biggest challenge

We have many, but the most common are alkaline soils, lack of moisture and extremes of temperature. Alkaline soils bind nutrients and can lead to iron chlorosis. Our soil is commonly described as “sandy loam” because it’s derived from ancient lava flows. The drainage is typically acceptable but requires the addition of nutrients (the value of adding extra sulfur cannot be overstated) and organic matter. The dairies in our area process waste into wonderful compost that is perfect organic material and easy to apply. The lack of moisture is solved by automatic irrigation systems, which most homeowners now have. The best way to reduce evaporation during our very hot summers is to use drip lines in garden-bed areas and use spray heads only in lawn areas. Reducing the size of lawns reduces the amount of water needed; turf grass is the highest water user. We deal with temperature extremes by using plants adapted to our zone, understanding the microclimates to make wise choices about site selection, mounding tender plants in the winter and adding supplemental moisture in the summer.

About Sharon

I’m co-prsident of the Magic Valley Master Gardeners. I started gardening beside my mama when I could only crawl. Actually, all I was doing was playing in the dirt but, in retrospect, I learned that gardening was calming to the spirit and the rewards many: vegetables frozen and canned to be used year round, flowers to beautify our home and for indoor bouquets, trees and shrubs to give shade under which to play and picnic, green grass serving as a mattress on the many summer “campouts” for my sisters and myself.

I have an acre of landscaping surrounding my home, which is also my office that I use as demonstration gardens for clients. Most clients tour my landscaping at some point as it is a benefit for them to see what trees, shrubs and perennials I’m recommending for their home.

When preparing to open my own landscape design studio five years ago, I took the Master Gardener course. It was invaluable for its comprehensive approach to all horticulture topics and I continue to use their many publications as a resource for my clients. My husband also appreciates the benefits of gardening, but he enjoys adding hardscapes to compliment the plant material. He has built a deck overlooking the Snake River canyon, a stream water feature, and a large pergola for the honeysuckle.

Idaho Master Gardeners