resources : Gardening Information : Spring

More Flagstaff Gardening Info: Spring | Summer | Winter

Early Spring

Pruning. This is a good time to complete any dormant pruning left over from last fall. Wait until blooming is complete before pruning spring-flowering trees and shrubs. Ideally, prune after the coldest temperatures start rising so that the newly exposed tissues won’t freeze and tear, but before bud-break so the sap doesn’t run from the cut.

Fertilizing. As spring bulbs start to emerge, apply a high-phosphorus fertilizer before it rains so the moisture will carry nutrients to the root zone (or water the fertilizer in).

Starting Seeds. It’s time to plan your flower and vegetable gardens so that you can determine when to start seeds indoors for transplanting later. Remember to rotate crops from last year’s locations to minimize disease and nutrient deficiency problems in the soil. Start cool-weather crops that need 8 weeks or more before transplanting.

Maintenance. It’s a good time to maintain garden tools. Sharpen blades, shovels, hoes, mowers, and other cutting tools. Oil moving parts on machinery. If you are starting seeds indoors or in a greenhouse, prepare sites and check systems.

Pest Control. On days warmer than 45 degrees, apply dormant oil spray to control scale insects that can cause significant damage to trees and shrubs later in the growing season. Inspect the bark of willows and aspens in particular for pests.


Mulch. Remember the mulch placed over tender perennials last fall? It’s time to start removing protective materials. The primary benefit of mulch is to keep the ground frozen longer in the spring, preventing the soil from repeatedly freezing and thawing. However, if left on too long after the temperatures begin to rise, mulch prevents light and air from reaching new buds and slows the warming of soil. Plants may stay dormant longer than necessary and those sensitive to moisture may rot. When really cold nights seem to be over, start pulling the mulch back. Leave some nearby so that if temperatures drop again you can put it back in place for the night.

Fertilizing. Trees and shrubs are beginning to put on new growth. Fertilize evergreen trees, perennials, and shrubs. If the soil is dry enough to work, you can add organic materials to your garden.

Starting Seeds. It’s time to start warm-weather transplants. If you have space, start some extra seeds a few weeks after the first batch, in case a late frost nips your plants after you put them in the garden.

Maintenance. If you left dried seed heads on flowers or shrubs last fall, it’s time to remove them as well as faded spring bulb flowers. Also remove thatch from lawns.

Late Spring

Mulch. Remove remaining winter mulch but leave a thin layer around the base of plants to protect them from drying spring winds.

Watering. If spring is dry, be sure to water to your plants. Depending on soil type, plants should receive a total of 2 inches of water per month, whether by rain or by water you provide. Occasional deep watering is preferable to frequent shallow watering. Be especially diligent about watering plants that have been in the ground less than 2 years, as they are still developing root systems.

Planting. Monitor nighttime temperatures to determine when it is warm enough to begin to set out and direct seed the cool-weather crops.

Maintenance. Weeds will be starting to grow. Eliminate them early to save time later. The most effective method is to remove roots with your favorite weed-digger. It is time to start using organic-based herbicides that work best on young plants.