Asparagus is a crop that rewards patience with abundance. It’s flavorful and highly nutritious, rich in fiber, iron, and antioxidants. And for over 2,000 years, gardeners have valued asparagus for its remarkable long-term harvests.
This guide walks you through everything you need to know to plant asparagus once and enjoy harvests for decades to come. You’ll learn how to:
- Choose the best variety.
- Establish asparagus in the first two years.
- Use the trench ridge method.
- Build stronger crowns by backfilling.
Step #1: Pick Your Planting Location
Because asparagus is a long-lived perennial that comes back every year, choosing your planting site is a long-term decision.
The best sites provide enough sun and air to build strong crowns, with soil that provides adequate nutrients and proper drainage. A gentle windbreak is helpful, as long as it doesn’t block sunlight, and you’ll want to avoid areas that get foot traffic.
If you get these fundamentals right, most of your work in the future will simply be routine maintenance.
The Best Soil for Asparagus
Once you’ve selected your plant’s long-term location, it’s time to prepare the soil. Your garden soil will need to be amended before planting to ensure a neutral pH, loose soil, organic matter, and fertilizer.
Drainage is critical, as asparagus crowns decline quickly in wet soil. The soil should never hold standing water, since roots can grow as deep as 6 feet.
If your soil is heavy clay or tends to stay wet, build a raised bed 12–18 inches deep using a blend of topsoil, compost, and coarse sand to improve drainage.
How to Prepare Your Soil
- Test First: Take a pH reading with an at-home kit and aim for a pH of 6.5 to 7.5.
- Adjust If Needed: If your soil’s pH is low, apply lime or wood ash; if it’s high, apply sulfur or organic material.
- Add Organic Matter: Work in 3 to 4 inches of aged compost using only fully composted manure.
- Loosen Deep: Double-dig or loosen soil to a depth of 12 to 15 inches.
- Apply Pre-Plant Fertilizer: Add a balanced slow-release fertilizer (e.g., a 10-10-10 formula) or organic alternatives like bone meal.
Step #2: Choose Crowns or Seeds
The next decision you’ll need to make is whether you will start growing asparagus by purchasing crowns or seeds.
Most growers start with bare-root crowns instead of seeds. Crowns are one- or two-year-old asparagus plants that already have root systems.
If this is your first asparagus bed, I recommend starting with crowns. Planting crowns offers a head start over seeds, allowing you to harvest three years after planting rather than four or five. For most gardeners, that time savings is worth the crowns’ slightly higher cost.
Do keep in mind, though, that seeds and crowns both require a cold dormancy period. This is an important consideration when selecting varieties and planning your planting schedule.
For another crop that grows from underground structures and benefits from careful early establishment, read our guide on how to grow ginger here.
How to Start Asparagus from Seed
Asparagus seeds can be purchased or saved from established beds.
Starting asparagus from seed has two primary advantages:
- Seeds are more economical.
- They give you access to a wider range of varieties.
However, seeds do need several years before harvest. Raising seedlings also requires more hands-on time.
If you’re sourcing seeds from existing asparagus plants, female plants produce red berries in late summer or fall. Each berry contains one to five black seeds. To save seeds, you’ll need to harvest fully red berries, mash them to release the seeds, rinse away the pulp, and allow the seeds to dry completely for one to two weeks.
After drying, the seeds will need to be cold-treated (stratified) before planting.
5 Steps to Start Asparagus from Seed
- Place seeds between damp paper towels in a sealed bag.
- Refrigerate for two to four weeks.
- Sow seeds in trays about 12 weeks before your last frost date.
- Maintain soil temperatures at 70 to 75 degrees Fahrenheit.
- Harden seedlings off gradually over seven to 10 days before transplanting.
- Transplant seedlings outdoors once they reach 10 to 12 inches tall and all risk of frost has passed.
How to Choose Healthy Crowns
If you’re starting with asparagus crowns, the quality of the crown directly affects the productivity of your bed.
Purchase your crowns from a reputable nursery or mail-order supplier that stores them properly in cool, dry conditions. Crowns sitting in a big box store at room temperature will deteriorate quickly.
Plant crowns that come in the mail within one to two days of arrival. If you can’t plant them immediately, keep them in a cool, dark location loosely wrapped in slightly damp paper, never sealed in an airtight container.
Signs of a Healthy, Bare-Root Crown
- Firm, Plump Roots: No soft spots, sliminess, or disease
- Multiple Buds: Intact and undamaged where spears emerge
- Full Root System: Fans outward in multiple directions
- No Shriveling: Deep shriveling shows improper storage
Expert Tip: One-year-old crowns are preferred over two-year-old crowns because they experience less transplant shock. They’ll adapt more easily to new soil conditions than older crowns with established root systems.
Step #3: Pick Your Asparagus Variety
Traditional asparagus varieties produce seeds that become a mix of male and female plants. Female plants use their energy to make seeds instead of spears, leading to a weedy bed full of asparagus seedlings.
Modern all-male hybrid varieties use all of their available energy on spear production, yielding three times the spears of older varieties. They’re also more vigorous and disease-resistant.
Wondering which asparagus variety to choose? The Jersey series, developed by Rutgers University, remains the most recommended for most growers.
3 Popular Jersey Asparagus Varieties
- Jersey Knight: Delivers reliable, high yields across a wide range of climates.
- Jersey Supreme: Emerges earlier than Jersey Knight, making it well-suited to short growing seasons.
- Jersey Giant: Produces large, thick spears with excellent flavor and slightly better cold tolerance.
3 Varieties for Extreme Heat or Cold
- Millennium: Bred for winter hardiness and able to withstand deep freezes (Zones 3–4).
- UC 157: Adapted to warmer regions (Zones 7–9), with mild winters.
- Apollo: Another reliable option for warm climates with consistent spear production.
Step #4: Plant Your Crowns
Once you have your crowns, planting them correctly is not complicated. However, the details matter if you want your crowns to settle in and begin spreading roots.
When to Plant Asparagus Crowns
Bare-root crowns should be planted in early spring, as soon as the soil is workable and has warmed to at least 50 degrees Fahrenheit at planting depth. In most temperate regions, this means you’ll plant your asparagus between mid-March and mid-May.
Use a soil thermometer to check: Push it down to 6 to 8 inches for an accurate reading at crown depth.
If you’re transplanting seedlings that were started indoors, wait until all frost risk has passed and nighttime temperatures are consistently above 40 degrees Fahrenheit.
Dig a Trench
Using a spade or garden fork, dig a trench 6 to 8 inches deep and about 12 inches wide down the length of your bed. As you dig, set the soil aside; you’ll need it for backfilling.
In heavy clay soil, reduce the depth to 4 to 6 inches to improve drainage.
If you’re planting multiple rows, space trenches 3 feet apart to give each row’s root system room to expand.
If you’re exploring other crops that rely on structured row and trench planting, check out our guide on how to grow onions here.
Create a Ridge and Place Your Crowns
- Create a raised ridge of soil running down the center of the trench.
- Shape the ridge mound so it sits 3 to 4 inches high.
- Center each crown on top of the mound, with the buds (where the spears emerge) facing upward.
- Drape the roots naturally down both sides of the mound.
- Never fold, bend, or crowd the roots to fit a flat-bottomed trench.
- Space crowns 12 to 18 inches apart.
As you’re placing your crowns, you can adjust spacing to suit your available space:
- Use 12-inch spacing for faster bed fill.
- Use 18-inch spacing for full mature size over 10 to 15 years.
- For most gardens, compromise at 15 inches.
Step #5: Slowly Backfill the Trench
After positioning your asparagus crowns, cover them with 2 to 3 inches of soil, just enough to anchor them and protect the buds. Leave the trench partially open as you firm this first layer gently with your hands to eliminate air pockets.
Water thoroughly so the soil settles around the roots. The soil should be damp, not soggy.
As spears grow, gradually add more soil about 2 inches at a time. Just make sure to always leave spear tips exposed above the soil. Continue this throughout the first growing season until the trench is full and level with the surrounding ground.
Once your trench is completely backfilled, apply a 3- to 5-inch layer of mulch across the entire bed. Wood chips or shredded leaves work well.
Step #6: Manage Asparagus in the First Two Years
The goal of growing asparagus in the first two years is simple: Build strong crowns.
During this period, you won’t harvest any spears. Instead, the goal is to allow all spears to grow into full, ferny foliage. The bigger and fuller the fern growth in year one, the stronger the crowns (and the larger your harvest) will be.
Once the bed is established, asparagus is relatively low-maintenance. The same seasonal routines you build early — watering, mulching, feeding, and weed control — can continue with minimal change year to year.
How to Properly Water Asparagus
Asparagus needs consistent moisture during active growth periods to bolster spear quality and crown strength. Aim to water about 1 to 2 inches per week during the growing season.
Drip irrigation is ideal, but sprinklers work well if used in the morning (you want foliage to dry quickly).
Once ferns die back in fall, watering is rarely needed unless conditions are extremely dry.
Weed Control and Mulching
Mulch is the primary tool for weed suppression in asparagus beds, and it reduces the need for cultivation that can damage shallow crowns. It also:
- Conserves moisture.
- Moderates soil temperature.
- Adds organic matter over time.
To apply mulch correctly, you’ll need to pull it back from emerging spears. Apply 3 to 5 inches in most regions, or 6 to 8 inches in cold climates. Refresh the mulch after ferns die back in fall.
As the bed matures, summer fern growth should shade the soil and suppress many annual weeds. Perennial weeds should be removed as soon as you see them. Avoid using pre-emergent weed control products, which can harm or even kill your crowns.
Fertilization
Your fertilizing routine should stay mostly consistent from year to year. You can adjust based on soil tests and product availability throughout the years. Test soil every 2 to 3 years to check pH and nutrient levels.
Follow this fertilizer schedule for asparagus:
- Early Spring: Apply balanced fertilizer before spears emerge.
- Midsummer: Apply a low nitrogen fertilizer (5-10-10) after harvest.
- Early Fall: Apply balanced fertilizer as ferns begin to turn yellow.
If organic matter like compost is available, that should be your first choice for fertilizer.
Step #7: Watch for Common Pests and Diseases
Good garden hygiene prevents most pest and disease problems in asparagus beds. Fall cleanup is important, though, as removing dead ferns eliminates overwintering sites for asparagus beetles.
In spring and early summer, check plants regularly and handpick asparagus beetles when numbers are low. If infestations increase, spray plants with neem oil or Spinosad (a naturally derived insecticide from a soil-dwelling bacterium).
Watch for asparagus rust in midsummer, which appears as orange-red spots on ferns. Remove all infected growth and immediately improve airflow. However, choosing to plant rust‑resistant asparagus varieties provides the best long-term protection.
Managing long-lived plants always requires consistent prevention strategies, so learn how to grow and care for hydrangeas in our guide here.
Step #8: Harvest Your Asparagus
Harvesting is the reward for all the work and patience of the previous years. Done correctly, especially in the early seasons, harvesting keeps your asparagus bed productive for decades to come.
At the beginning of year three, spears will come up thicker and stronger than in previous seasons. This increase in size is your signal that the crowns have stored enough energy to support harvesting.
When to Harvest Spears
Harvest asparagus spears when they are 6 to 8 inches tall and the tips are still tight and closed. At this stage, they are tender and have the best flavor.
If the tips start to open and look feathery, the spear is past its prime and will be tougher.
Check your bed daily during the harvest season. During warm weather, spears can grow up to 10 inches in 24 hours.
How to Harvest Asparagus
There are two common harvesting methods:
- Snap: Hold the spear near the base and bend it until it snaps naturally at the tender point.
- Cut: Use a sharp knife to cut the spear at or just below the soil surface.
It’s best to harvest in the early morning, when spears are firm and full of moisture.
Once you’ve harvested asparagus spears, plan to use them immediately for best flavor. Fresh asparagus can be eaten raw straight from the garden.
Alternatively, you can store spears upright in a little water in the refrigerator.
When to Stop Harvesting
Your asparagus spears’ thickness will tell you when to stop. As long as new spears emerge thick and strong, harvesting can continue.
When new spears start coming up pencil thin, stop harvesting that crown and let the spears grow into ferns. Continuing to harvest thin spears weakens the crown and shortens the lifespan of the bed.
Asparagus Harvest Length by Year
As your asparagus bed matures, the harvest time will gradually increase:
- Year 3: Harvest for 2 to 4 weeks.
- Year 4: Harvest for 4 to 5 weeks.
- Years 5 and Beyond: Harvest for 6 to 8 weeks, but never more than 8 weeks.
After harvesting ends each year, let all remaining spears grow into ferns. These ferns replace the energy that was used to make the spears you harvested and prepare the plants for spring.
Fall and Winter Asparagus Care
Fall cleanup and winter preparation work as a single, continuous process. Cleanup removes diseases and pests from your asparagus, while mulching protects crowns through winter.
When the first hard frost hits and the ferns turn yellow and dry, wait to cut them down until they are completely dead. This natural dieback allows the plant to move nutrients from the ferns back into the crown.
About one to two weeks after that first frost, cut all ferns down to about 2 inches above the soil and remove them from the bed. Do not compost the removed ferns unless your compost pile gets very hot (140 to 160 degrees Fahrenheit), since the debris can harbor asparagus beetles and disease.
After cleaning up, water the bed if the soil is dry, then apply your winter mulch. At this point, the crowns are dormant and storing energy for the next spring.
Winter Protection by Zone
- Zones 5–6: Apply a 3- to 5-inch layer of mulch to insulate while still allowing airflow.
- Zones 3–4: Increase mulch depth to 6 to 8 inches. Before the coldest weather arrives, place burlap or row cover fabric over the mulch.
- Zones 7 and Higher: A light mulch layer is enough to retain moisture and suppress weeds.
Managing Freeze–Thaw Cycles
In colder regions, temperature fluctuations can be as damaging as the cold itself.
- Freeze–thaw cycles push crowns closer to the surface.
- Adding a layer of mulch moderates soil temperature.
- Reduce soil movement to keep crowns protected and anchored.
Remove Mulch Gradually in Spring
Removing winter mulch too early can slow soil warming and delay spear emergence. Instead, remove it gradually to allow the bed to transition smoothly from dormancy into active growth.
Here’s how to make the change when spring arrives:
- Watch for emerging spear tips.
- Pull thick mulch back gradually to let soil warm evenly.
- Leave a thin layer for weed control and moisture retention.
Refreshing an Old Asparagus Bed
Once your asparagus has been growing for years, most beds hit peak productivity between years five and 10. This is when you’ll get thick, abundant spears with very little maintenance.
At full maturity, a healthy bed delivers a consistent harvest window of 6 to 8 weeks each spring. Over time, however, even well-maintained beds naturally decline and will need a refresh.
Signs Your Asparagus Needs a Refresh
When productivity drops, the bed provides clear signals that a refresh is needed:
- Spears are consistently thinner than a pencil.
- The harvest window shortens year over year.
- Fewer spears emerge despite normal care.
- Soil tests show big pH changes or nutrient depletion.
How to Refresh an Aging Bed
Refreshing your asparagus bed is best done in early spring before any new growth emerges.
- Carefully divide mature crowns, ensuring each division has several healthy buds and a strong root system.
- Replant divisions into freshly amended soil.
- As you plant, work in generous amounts of compost.
- Check soil pH to confirm it’s in the 6.5 to 7.5 range.
After replanting, avoid harvesting from the divisions for at least one full growing season. This rest period allows the crowns to re-establish and rebuild stored energy.
Starting a Second Bed
Alternatively, if your original asparagus plants are still producing, you can establish a new bed using newer, improved varieties. New cultivars are introduced regularly, often with better disease resistance or climate adaptability.
This staggered approach helps avoid gaps in harvests. While the new bed establishes itself, the older bed remains productive, allowing you to phase it out gradually once the replacement reaches maturity.
Final Tips for Success
One of asparagus’s greatest advantages is that it’s a long-term crop. Plant it well, care for it, and it will give back year after year. If you invest extra care at the beginning and play the long game (and resist the urge to harvest too early), strong crowns will develop.
As seasons pass, your asparagus crowns will grow stronger, and your harvests will grow bigger with less effort. Pay attention early, let the plants guide your timing, and the garden will do the rest.
Happy growing!