Ted Smith

If you’ve lived in Park County for more than a season, you know that March in the Big Horn Basin is a masterclass in psychological warfare. One day we’re basking in 50-degree sunshine, and the next, the horizontal wind is reminding us exactly why we only see 7-10 inches of moisture a year. While it’s tempting to rush outside after several days of sunny, warm weather, gardening is a game of patience and preparation. This article is dedicated to helping you navigate our unique ‘Zone 4/5’ challenges — from protecting your soil from those relentless winds to picking the varieties that can actually handle a late frost in June. Grab your seed packets and a cup of coffee; it’s time to start planning.

1. Wake-up the soil early (but not too early)

As soon as the top few inches of soil thaw, gardeners can begin loosening beds with a garden fork. Avoid aggressive turning; our sandy-loam and clay-loam soils lose structure easily.

What to do now:

Remove leftover plant debris to reduce overwintering pest habitat.

Add 1–2 inches of compost — or Canadian sphagnum peat moss, which has a low pH of 3.0 to 4.5 and will effectively reduce soil pH.  

If you use low tunnels or cold frames, open them on warm days to prevent overheating.

Sharpen tools, clean pots in a 1:9 bleach solution, and check irrigation systems for winter damage.

2. Start cool-weather crops indoors

March is the ideal time to start hardy vegetables that thrive in the cool spring. Remember to use grow lights; our early spring sun isn’t always enough for leggy seedlings.

Start indoors now:

Cabbage, broccoli, cauliflower, Brussels sprouts

Onions (if you haven’t already)

Leafy greens like chard and kale

Transplanting will come later, but early starts help gardeners dodge our typical late-May frosts.

3. Start some warm-weather crops Indoors

Eggplant

Melons, squash

Peppers, tomatoes

Use grow lights; our early spring sun isn’t always enough for leggy seedlings.

Again, transplanting will come later, but early starts help gardeners dodge our typical late May frosts.

4. Hydrate your landscape trees

Even with snow still in the mountains, our valley landscapes remain critically dry. Evergreens especially lose moisture through winter.

If daytime temps reach 40 degrees F-plus:

Winter/spring watering is critical here. If the ground isn’t frozen, trees and shrubs likely need a deep drink in the root zone to prevent “winter kill” from our dry winds. It also reduces the risk of borers moving into drought-stressed trees.

5. Prune fruit trees before bud break

March is the final window to prune apples, pears, and plums.

Focus on:

Removing damaged, crossing, or inward-growing branches

Opening the canopy for airflow (helps fight fire blight)

Keeping trees at a manageable harvest height

Trim suckers at the base of the tree

Remove vertically growing water sprouts from scaffold (fruit bearing) branches — they waste energy and bear no fruit

6. Begin early weed control

Our primary spring weeds — Canada thistle, chickweed, field bindweed (morning glory), kochia and Russian thistle — are easier to control now.

Pull or hoe seedlings when they are tiny. Roots are shallow, and you’ll prevent thousands of seeds from forming later.

Be aware that some lawn care herbicides can harm shrubs and trees — particularly grapes, redbuds, maples, elms and conifers like pines/spruces are sensitive! 

In closing, you are invited to the third annual Harvest Wyoming Conference on April 25 at the Cody Holiday Inn. Online registration is required for this limited attendance free event. For more information: wyoextension.org/harvestwyo/.

(Ted Smith is the UW Extension Horticulture Program coordinator for Park County.)