If you’re a gardener in Minnesota, knowing when to plant asparagus is the first step to a successful perennial bed. For optimal spring growth, timing your planting with our specific climate is absolutely essential.
Getting this right means your asparagus crowns will establish strong roots before winter and reward you with vigorous spears for decades. This guide walks you through the perfect schedule and simple steps for Minnesota growers.
When To Plant Asparagus In Minnesota
This headline is your golden rule. In Minnesota, you have two primary planting windows: early spring or late fall. The spring window is by far the most common and recommended for beginners.
Your target is to get those crowns in the ground as soon as the soil is workable. This typically means late April through mid-May, but it truly depends on your location and the weather each year.
Understanding Your Minnesota Planting Zone
Minnesota spans USDA hardiness zones 3a to 5a. This range affects your exact planting date.
- Zones 4 & 5 (Southern MN): Aim for mid to late April. The soil thaws and warms a bit earlier here.
- Zone 3 (Northern MN): Plan for early to mid-May. Wait for the frost to leave the ground and the soil to dry slightly.
The best indicator isn’t the calendar, but the soil itself. Go outside and grab a handful. If it’s thawed, crumbles easily, and isn’t waterlogged, it’s time to plant. Trying to work cold, soggy soil will damage its structure and harm your crowns.
Why Fall Planting Is a Risky Alternative
Some experienced gardeners plant asparagus in late fall, just as the crowns are going dormant. The goal is for them to settle in over winter and sprout first thing in spring.
In Minnesota, this is a riskier move. If you try it, you must time it perfectly—about 4-6 weeks before the ground consistently freezes, often early October. The danger is that a warm spell could trigger growth that is then killed by a hard freeze, wasting the crown’s energy. For most people, spring planting is the safer, more reliable choice.
Choosing the Right Asparagus Variety
Your planting date is crucial, but starting with a variety suited to cold climates sets you up for sucess. Look for these hardy, proven types:
- Jersey Series (Jersey Knight, Jersey Giant, Jersey Supreme): All-male hybrids that produce more spears and are very cold-tolerant.
- Purple Passion: Offers beautiful purple spears and a slightly sweeter flavor; it’s surprisingly winter-hardy.
- Mary Washington: A reliable, old-fashioned heirloom variety that handles cold winters well.
Purchase healthy, one-year-old crowns from a reputable nursery. They should be firm, grayish-brown, and have numerous thick roots.
Step-by-Step Planting Guide for Spring
Follow these steps to give your asparagus the best possible start. Proper planting is an investment in the future.
1. Site Selection and Soil Prep
Asparagus needs full sun—at least 8 hours daily. The bed must have excellent drainage to prevent crown rot. This is a perennial crop, so choose a spot where it can grow undisturbed for 15+ years.
Prepare the soil in the fall before spring planting, if you can. Work in a generous amount of compost or well-rotted manure. Aim for a soil pH between 6.5 and 7.0. You can test your soil and amend it accordingly.
2. The Trench Method: How to Plant Crowns
- Dig a trench 12 inches wide and 8-10 inches deep.
- Create a 4-inch high mound of soil down the center of the trench.
- Space the crowns 12-18 inches apart along the mound, draping the roots down the sides.
- Cover the crowns initially with just 2-3 inches of soil.
As the spears grow through the season, you will gradually fill in the trench with more soil until it’s level by fall. This deep planting protects the crowns and encourages strong root development.
3. Immediate Aftercare
Water the planted crowns thoroughly. Keep the soil consistently moist (but not soggy) during the first growing season. Apply a light layer of straw mulch to supress weeds and retain moisture.
Caring for Your Asparagus Bed the First Two Years
Patience is key! You must not harvest any spears in the first year. In the second year, you can pick a few for just 2-3 weeks. This allows the plant to build a massive, sturdy root system.
- Weeding: Weed carefully by hand, as asparagus roots are shallow and easily damaged.
- Watering: Provide 1-2 inches of water per week during dry spells.
- Fertilizing: Top dress with compost each spring and again after harvest once established.
In late fall, after the ferns have turned yellow and died back, you can cut them down to ground level. This helps prevent disease from overwintering. Adding a fresh layer of mulch after cutting back is a good idea for winter protection, especially in zone 3.
When to Finally Harvest Your Asparagus
The long-awaited reward begins in the third spring. When spears are about 6-8 inches tall and as thick as your finger, you can start harvesting.
Use a sharp knife to cut them at or just below the soil surface. The harvest season lasts for 6-8 weeks. Always stop harvesting by early July to let the plant recharge its energy for next year by growing its ferny top.
Common Problems and Solutions in Minnesota
Even with perfect timing, you might face a few challenges.
- Slow Emergence in Spring: Don’t panic. Cold, wet springs can delay spears. They will appear when the soil warms sufficiently.
- Asparagus Beetles: Hand-pick the orange and black adults and crush their black eggs. For severe infestations, use neem oil.
- Rust or Fusarium Wilt: Choose resistant varieties (like the Jersey series) and ensure good air circulation by not overcrowding plants.
FAQ: Your Minnesota Asparagus Questions Answered
Can I grow asparagus from seed in Minnesota?
Yes, but it adds two extra years to establishment. Start seeds indoors in late winter and transplant seedlings in summer. You’ll wait an additional year before your first light harvest compared to using crowns.
What if I miss the ideal spring planting window?
You can plant potted asparagus crowns later in spring or early summer, but they will require more attentive watering. Avoid planting during the hot, dry months of July and August. Late summer planting is possible if you can keep them well-watered, but spring is still best.
How do I protect my asparagus over a Minnesota winter?
After cutting back the dead ferns, a 4-6 inch layer of straw or shredded leaves applied after the ground is frozen is excellent insulation. This prevents damaging freeze-thaw cycles. Remove most of it in early spring as the soil begins to warm.
Why are my asparagus spears so thin?
Thin spears in an established bed often indicate fatigue from over-harvesting the previous year or a need for nutrients. Ensure you stop harvesting on time and apply compost annually. In young beds, thin spears are normal for the first full harvest season.
Getting your asparagus planting schedule right in Minnesota is the foundation for a low-maintenance, high-reward crop. By focusing on that early spring window as soon as your soil is ready, choosing a hardy variety, and planting with care, you’ll be set for many springs of delicious, homegrown asparagus. The wait is worth it.