When To Plant Asparagus In Colorado

If you’re a gardener in Colorado, knowing when to plant asparagus is the first step to a successful perennial bed. The optimal spring planting times are crucial for giving your crowns the best start in our unique climate.

Asparagus is a long-term investment, often producing for 15 years or more. Getting the timing right in Colorado means working with our unpredictable springs, varying elevations, and occasional late frosts. Let’s break down the best schedule for your area.

For most Colorado gardeners, the ideal window for planting asparagus crowns is from early April to mid-May. The key signal is soil temperature. You should plant when the soil is workable and has warmed to about 50°F.

This typically happens after the last hard frost but before daytime temperatures get consistantly hot. Planting too early in cold, wet soil can cause the crowns to rot. Planting too late stresses the plants with immediate heat.

How Colorado’s Climate Affects Your Planting Date

Colorado isn’t one single climate. Your specific timing depends heavily on where you live.

Front Range Urban Corridor (Denver, Colorado Springs, Fort Collins): Aim for mid-April to early May. The last frost date is usually around May 5th, but soil often warms enough a week or two before that.
Western Slope & Lower Valleys (Grand Junction, Palisade): You can often plant earlier, in late March or early April, thanks to milder winters and warmer springs.
High Mountain Regions (Above 7,000 feet): Wait until late May or even early June. Soil takes much longer to warm up at higher elevations. Patience is essential here.
Eastern Plains: Target late April, but be prepared for wind protection. The soil can warm quickly, but frost dates can be variable.

Preparing Your Asparagus Bed: A Critical First Step

Since asparagus lives for decades, bed preparation is the most important work you’ll do. It’s best to prep the bed in the fall before your spring planting, but early spring works too if the soil isn’t frozen.

Choose a Sunny Site: Select a spot with full sun—at least 8 hours daily. Good drainage is non-negotiable; asparagus hates wet feet.
Dig Deep: Asparagus roots penetrate deeply. Till or dig the soil to a depth of 12 to 15 inches.
Amend the Soil: Colorado soil is often heavy clay or sandy. Mix in a generous amount of compost or well-rotted manure. Aim for a loose, fertile, and well-draining texture.
Check pH: Asparagus prefers a slightly alkaline soil, between 6.5 and 7.5. Colorado soil is often already in this range, but a simple test can confirm.

Step-by-Step Planting Guide

Once your soil is ready and the timing is right, follow these steps.

1. Selecting and Soaking Crowns

Purchase fresh, firm, one-year-old crowns from a reputable source. Before planting, soak the crowns in lukewarm water for 15-20 minutes. This rehydrates them and gives them a boost.

2. The Trench Method

This is the traditional and recommended way to plant asparagus.

Dig a trench 12 inches wide and 6 to 8 inches deep.
Create a small mound of soil down the center of the trench, running lengthwise.
Place the crowns on top of the mound, spacing them 12 to 18 inches apart. Drape the roots down over the sides of the mound.
Cover the crowns initially with just 2 to 3 inches of soil.

3. Gradual Filling

As the shoots begin to grow through the initial soil cover, gradually add more soil to the trench. You’ll fill it in completely over the course of the first growing season. This method allows the young stems to strengthen without being burried to deep to soon.

Caring for Your New Asparagus Plants

The first two years are about building a strong plant, not harvesting.

Watering: Water deeply and consistently, about 1-2 inches per week. Deep watering encourages deep root growth, which is vital for drought tolerance in Colorado.
Mulching: Apply a 3-inch layer of straw or shredded wood mulch. This conserves moisture, suppresses weeds, and moderates soil temperature.
Weeding: Weed carefully by hand. Asparagus doesn’t compete well with weeds, especially when young.
Fertilizing: In early spring and again after the growing season ends, side-dress with compost or a balanced fertilizer.

The Waiting Game: When to Harvest

Resist the temptation to harvest too soon! This is a common mistake.

Year 1: Do not harvest. Let all the ferns grow to feed the crown.
Year 2: You can harvest very lightly for 2-3 weeks if the spears are robust. If they’re thin, wait another year.
Year 3 and Beyond: Harvest spears for 6-8 weeks in spring. Stop when spear diameter starts to shrink to pencil-size.

Always allow the remaining spears to grow into tall, leafy ferns after you stop harvesting. These ferns are the engine that produces next year’s crop.

Common Mistakes to Avoid in Colorado

Planting too deep initially: Using the trench method prevents this.
Overharvesting too early: It weakens the plant for future years.
Poor site selection: Not enough sun or poor drainage leads to failure.
Ignoring winter care: After the ferns die back in fall, cut them down to the ground and add a layer of mulch for winter protection, especialy in colder zones.

FAQ: Asparagus Planting in Colorado

Can I plant asparagus from seed in Colorado?

You can, but it adds an extra 2-3 years before your first harvest. Starting with one-year-old crowns is much more efficient and gives you a head start.

What are the best asparagus varieties for Colorado?

Choose male hybrids like ‘Jersey Knight’ or ‘Millennium.’ They are more productive and don’t waste energy on seeds. They also tend to be more cold-tolerant, which is a plus here.

Is fall planting an option?

It’s generally not recommended in Colorado. Our winters can be harsh and unpredictable, which can heave or damage newly planted crowns. Spring planting is the safer, more reliable choice.

How do I protect young shoots from late frost?

If a hard frost is forecast after spears have emerged, cover them with a layer of straw or a frost cloth overnight. They are more tender than the established crown itself.

Getting your asparagus planting time right in Colorado sets the stage for decades of delicious spring harvests. By aligning your schedule with local soil temperatures and following through with careful bed preparation and patience, you’ll be rewarded with a low-maintenance, high-yielding perennial vegetable that thrives in our Rocky Mountain conditions. Remember, the work you do in the first season pays off for years to come.