Spring Garden Clean-up
If you are like me, the autumn clean-up in the garden often rolls over into spring. With warmer days bringing thoughts of planting, now is the time to finish up (or even begin) those garden clean-up chores. Start with cleaning your tools and sharpening blades if needed.
One preliminary note – the severe sudden cold that the Front Range experienced in November of 2014 will lead to damage of plants which will not become apparent until this spring in 2015. Temperatures dropped from the high 60’s to minus 14 degrees over 4 days causing damage to needles and bud on trees, possibly killing other garden ornamentals, and freezing roses down to the ground. See the following Landscape Health Bulletin from the Extension Service for details on trees and how they may be affected: https://plantclinic.agsci.colostate.edu/files/2014/06/Polar-vortex-bulletin-Feb-2015.pdf .
Since some deciduous trees and bushes are bare of leaves and some are still dormant, assess them now for pruning needs. Trim out branches that cross one another and rub together, or that were broken or damaged by wind or snow loads. It is better to wait on pruning such trees as birch, maple, walnut, and elms. They will often “bleed sap” when pruned in the spring and respond better to pruning in the summer after leaves grow and turn a full summer green.
Do not prune spring blooming trees and shrubs at this time. The flower buds were set in the summer or fall of the previous year and pruning will remove this year’s blossoms.
Cut back dead leaves on perennials and leggy stems on ornamental grasses. Trim woody perennials which only bloom on new wood, such as lavender or buddleia, after hard frost danger has passed. Remove and compost debris from dead annual flowers, the spent dry leaves from irises, and any remaining ground-fall leaves not being utilized for mulch.
Spring garden clean-up time is great for an early start on weeding. When the ground is soft and damp and the weeds are small, it is much easier to remove them than to wait until they are ready to swallow your ornamentals. Weed a little every time you tour your beds, and the job will not become overwhelming (we do hope.)
When perennials start to emerge, it is an ideal time to divide and transplant them. As you do so, assess your beds for the need for additional mulch. Also, now is a good time to check out any irrigation systems, particularly drip hoses and soaker hoses, for any leaks and holes needing repair. Add mulch where needed (or wait until you add any new plants to the beds) and edge beds anew.
What about soil amendments? Now is a good time for a soil test if you have not submitted one recently, particularly for ornamental and vegetable gardens. Test kits are available from your local extension office and some nurseries and greenhouses. A CSU fact sheet on soil tests is available at the following link: http://www.ext.colostate.edu/mg/gardennotes/221.html
Although it is tempting to trim all the dead wood on roses, it is best to wait until the end of April or early May. (The Denver Rose Society suggests waiting until the forsythia are blooming in your neighborhood.)
You should also get your containers ready for the gardening season. Clean out any dead plants, add additional container soil, if necessary, and start designing for spring. Consider some cool weather crops like lettuce or spinach for early containers.
Do you have a compost pile? Now is a good time to turn it and get it ready for use. If you have mature compost, you may wish to apply some to beds before mulching and planting. Wait for the soil to warm before planting tender annuals, generally around Mother’s Day in the Denver area. You can plant early cool-weather spring vegetables as soil conditions allow, usually as early as the beginning of April.
If you have early blooming bulbs such as crocus and tulips, do not cut the foliage from the spent blooms. The foliage is busy making food for next year’s bulbs and flowers.
These tips will get you started on a new canvas for your artful and fruitful spring and summer garden.
By Mary Beth Cooper, Denver County Master Gardener