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  • David Salman

Spring Garden Clean-up

March 20th is the spring equinox and is officially the first day of spring in 2021. Winter is retreating as we get excited about getting back into the garden. Here is a guide to help you prioritize your spring "To Do" list. Read on to learn essential gardening tips to do to get your garden ready for another growing season.

March Watering

While the mountains and the SF Ski Basin are getting some snow this winter, down here at 7,000 ft. elevation here in town and the surrounding areas, conditions are very dry. We need to water our gardens and last season's transplants. Don't turn on your drip systems and sprinklers as the freezing temperatures will damage them. Instead, use a sprinkler and hose to water when day temperatures are at least 45° F.

Set a timer and move the water every 30 to 45 minutes or longer so the ground gets good and damp. Any transplants in the ground 2 years or less must be watered every 2 to 4 weeks depending on how much sun hits the planting sites; the more sun the more frequent the watering. Be sure to disconnect the hose from the faucet and drain the hose after each day's use. We strongly recommend using the Dramm dial-a-pattern sprinkler, available from local hardware stores and garden centers around town. (See the sprinkler pictured.)

Get Your Tree & Shrub Pruning Done Very Soon

Deciduous Shrubs and Trees: The time for hard pruning of shade, fruit, and flowering trees and spring-blooming shrubs has passed once we reach the end of March. As a general rule of thumb, the primary pruning season is done once the leaf and flower buds begin to swell.

Summer blooming shrubs like Russian Sage (Perovskia), Blue Mist Spirea (Caryopteris), and Butterfly Bush (Buddleia davidii and hybrids) can be cut back in mid-spring.

* Russian Sage should be cut back hard in mid-spring, leaving stems 12 to 15 inches tall. This should be done every spring to keep them blooming heavily. This is also the time to dig up any "suckers" (new stems pushing up from the ground around the original plant) to keep your Russian Sage in bounds and prevent it from overtaking its neighbors.

* Blue Mist Spirea and Buddleia davidii should be cut back by 1/3 to 1/2 of their height every third year (not annually) to re-invigorate the shrubs and encourage blooming.

* Roses should NOT be pruned until later in spring. Early May is ideal. Pruning stimulates roses to grow, which is not what you want to do when the nights are still frosty in March and April. And don’t prune roses too hard—remove only the top 1/3 of the stems (or less), and thin out any crossed interior branches.

Clean Up Your Perennials

In late March and early April, it's time to cut back our perennials. Herbaceous perennials greet the spring with dead, above-ground stems and leaves. In general, these perennials will show you where to cut. Look for a low mound of new, green foliage at the base of the old dead stems, and cut off last year’s brown stems just above the new green foliage.

Evergreen perennials like Rosemary, Lavender, Iberis (Candytuft), Beardtongue (Penstemon), Hesperaloe (Texas Red Yucca), and others only need to have any winter-killed stem tips and leaves removed. Don't cut back evergreens to ground level like their herbaceous neighbors. Doing so will injure or kill these evergreens.

* Lavender (Lavandula)—The winter 2020-2021 weather has caused some die-back of the foliage and stem tips. So to get these ornamental herbs pruned for the new growing season, I'm recommending to cut the plants back hard this spring to prune off the winter die-back. We may need to cut them back by 1/3 of their height. But before you cut, wait until late March-early April when you can see tiny green leaves beginning to push out from the old woody stems. This will show you how much of the old branches have been damaged by winter cold/desiccation. Shear the plants with pruning shears to remove the dead branches cutting above where the new growth is emerging from the old stems. Leave a nice, rounded mound of stems and foliage. Remove any old, dead stems from the plant's interior.

*Beardtongue (Penstemon)—Cut back the old flowering stems and any lanky stems to leave a nice, rounded mound of evergreen leaves and stems. This will re-invigorate the plants and give the flowering stems a more even shape later in the season.

- Other evergreen perennials—Simply cut off any winter-killed stem tips and foliage to leave a nice, mounded plant.

Cut Back Ornamental Grasses

Mid-spring marks the time to cut back your ornamental grasses. There are two categories of grasses: cool season and warm season growers. They are handled differently during spring clean-up.

Warm-season grasses include Little Bluestem (Schizachyrium), Big Bluestem (Andropogon), 'Blonde Ambition' Blue Grama (Bouteloua), Muhly (Muhlenbergia), Prairie Switchgrass (Panicum), Chinese Maidenhair Grass (Miscanthus), Giant Sacaton (Sporobolus wrightii), and others. They should be cut back in April. Leave about 2 to 4 inches of stubble standing—tall growers should be left with about 4 inches and smaller growers should be left with about 2 inches. After removing the dead foliage, scratch out the grass clumps with gloved hands to remove old dead stems from the interior of the clump. This gives the new growth room to push up toward the sun.

Cool-season grasses, like Blue Avena Grass (Helictotrichon), Fescues (Festuca), Silky Thread Grass (Nassella), and 'Karl Foerster' Feather Reed Grass (Calamagrostis) have evergreen foliage that should not be cut to the ground unless the winter cold has turned the foliage completely brown. Instead, vigorously "comb out" dead leaves with gloved hands and clip off the dead leaf tips. Also, clip or pull off old seedhead stalks to remove them from the foliage and make room for the flowering stems that push up in late spring.

Divide Old Grass Clumps

If the interior of your established grass clumps seem to have a significant amount of dead stems, it’s time to dig up the clump and divide it. Typically this is necessary once every 3 to 4 years. Cut the clump into quarters and re-plant a piece into the same hole. While you’re there, be sure to enrich the soil with some compost and Yum Yum Mix to help replenish the soil’s nutrient levels. Make new planting holes for the other pieces of the original clump or gift them to a friend. Note that the landscaper left too much dead foliage on the grass after the pieces have been replanted, cut them back further so that only 2 to 4 inches of stubble remains.

Mow Your Native Grass

grama grass field needing to be mowed

If parts of your yard are covered in native grasses like Blue Grama (Bouteloua gracilis) and last summer’s seed heads are still standing, March is a good time to mow them off. Mowing will reduce fire danger later in the season when the winds kick up and the foliage gets crispy dry. Set the mower deck on the highest setting and go to it.

Feed the Soil

If you forgot to feed your soil last fall with an ample application of Yum Yum Mix, you can catch up now. Yum Yum Mix is an all-natural fertilizer specifically formulated for our northern New Mexico soils. My long-term experience with this fertilizer has demonstrated that it supports healthy, living soils and provides the essential nutrients that make all types of plants robust and resilient.

I like to spread it over the top of the soil and scratch it in with a hand cultivator or small, stiff hand rake.

Water Deeply to Flush Yum Yum Mix into the Soil Surface

Once the Yum Yum Mix has been spread and scratched into the soil’s surface, I like to use a sprinkler (on a calm, windless day) to moisten the ground and Yum Yum Mix. Moisture helps the soil organisms start to digest the ingredients and break them down. This enables the plants to utilize the nutrients later in the spring as their roots become active when the soil thaws out.


After watering, cover the area with a good 1- to 2-inch layer of whatever mulch you’re using. By thickening up the mulch layer, you will ensure that the sun and wind don't evaporate essential moisture, keeping it in the soil for the plants to use.

Mulching will also help to keep the soil cold, so your plants don’t wake up too early and suffer from late frosts that are a regular part of our erratic spring weather. Mulching under fruit trees is especially important for this very reason.

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