If you want a productive asparagus patch that lasts for decades, you need to start with the right foundation. A critical part of that is knowing exactly how far apart do you plant asparagus. Proper asparagus spacing gives these perennial plants room to establish productive crowns for years. Crowd them, and you’ll get thin spears and weak plants. Give them too much room, and you waste valuable garden space. This guide will walk you through the precise measurements and methods to get your asparagus bed off to a perfect start.
How Far Apart Do You Plant Asparagus
The standard, recommended spacing for asparagus is 18 inches apart within the row, with rows spaced 4 to 5 feet apart. This measurement applies whether you are planting one-year-old crowns or starting from seed. This 18-inch spacing allows each mature asparagus plant enough space to develop a massive root system without competing with its neighbors for nutrients and water. The wide row spacing is crucial for two reasons: it gives you ample room to walk between the beds for weeding and harvesting, and it allows for excellent air circulation, which helps prevent fungal diseases like asparagus rust.
Why Asparagus Spacing Is Non-Negotiable
Asparagus is not like a tomato plant that you pull out at the end of the season. It’s a long-term investment. A well-cared-for asparagus bed can remain productive for 20 years or more. The plants you put in the ground this spring will be there for a very long time, so their initial placement is critical. Incorrect spacing leads to a host of problems that can shorten the life of your bed and reduce your harvest.
Consequences of Planting Asparagus Too Close
When asparagus crowns are planted too close together, they compete fiercely for resources. This results in several issues:
- Thin, Spindly Spears: The most immediate sign of overcrowding is the production of skinny spears, even on mature plants.
- Reduced Yield: Crowded plants produce fewer spears overall because they lack the energy reserves from insufficient root growth.
- Increased Disease Pressure: Poor air circulation from dense foliage creates a humid environment where diseases like fusarium crown rot can thrive.
- Shorter Bed Lifespan: The intense competition weakens plants over time, causing the bed to decline and become unproductive years earlier than it should.
Considerations for Planting Asparagus Too Far Apart
While less detrimental than overcrowding, giving asparagus too much space has its own downsides. The primary one is inefficient use of garden real estate. Asparagus plants spaced more than 18 inches apart in the row will still thrive, but you’ll be growing fewer total plants in your available area, which means a smaller harvest. The wide row spacing of 4-5 feet, however, should generally be maintained regardless, as it is essential for maintenance.
Step-By-Step Guide To Planting With Perfect Spacing
Now that you know the target measurements, let’s put them into practice. Here is the complete process for planting asparagus crowns with ideal spacing.
Step 1: Preparing the Planting Site
Site preparation is the most important physical work you will do for your asparagus. These plants demand deep, well-drained, fertile soil.
- Choose a Sunny Location: Select a site that receives at least 8 hours of full sun daily.
- Clear and Loosen the Soil: Remove all weeds and grass. Till or dig the soil to a depth of at least 12 inches.
- Amend the Soil: Asparagus loves rich soil. Incorporate a generous amount of compost or well-rotted manure into the entire planting area, not just the holes. Adding a balanced, slow-release fertilizer at this stage is also beneficial.
Step 2: Trenching for Asparagus Crowns
Asparagus is typically planted in a trench, which allows you to gradually cover the crowns as they grow. This method encourages strong root establishment.
- Dig the Trench: Dig a trench that is 12 inches wide and 6 to 8 inches deep. The length depends on how many crowns you have.
- Space the Crowns: Place the asparagus crowns in the trench, spacing them 18 inches apart from center to center. Spread the roots out evenly so they fan out laterally.
- Backfill Gradually: Initially, cover the crowns with just 2 inches of soil. As the spears grow over the first season, gradually fill in the trench with more soil until it is level.
Step 3: Setting Up Rows
If you are planting more than one row, measure carefully to ensure proper alleyways between them.
- Use stakes and string to mark your first row and trench.
- Once the first trench is dug, measure 4 to 5 feet from its center to mark the center of the next row.
- Dig the second trench parallel to the first. This wide alley is your permanent walking path.
Special Spacing Scenarios And Varieties
While the 18-inch rule is standard, some situations and specific varieties call for slight adjustments.
Spacing for Asparagus Grown from Seed
Starting asparagus from seed is more time-consuming but less expensive. The spacing goal is the same, but the process differs.
- Start seeds indoors 12-14 weeks before your last frost date.
- Transplant seedlings to a nursery bed, spacing them 3 inches apart.
- In their first full spring, transplant the young crowns to their permanent bed, using the standard 18-inch spacing. This extra year of growth is why seed-started asparagus takes longer to produce a harvest.
Spacing for Different Asparagus Varieties
Most common hybrid varieties, like ‘Jersey Knight’ or ‘Purple Passion’, conform to the standard spacing. However, some heirloom or particularly vigorous varieties may need more room.
- Vigorous Hybrids (e.g., Jersey Series): Stick to 18 inches. They are bred for strong, upright growth.
- Large Heirlooms: If planting a robust heirloom like ‘Martha Washington’, consider spacing crowns 20 to 24 inches apart for optimal growth.
- Male vs. Female Plants: Modern all-male hybrids (like Jersey Supreme) are more productive and don’t waste energy on seeds. They can be spaced reliably at 18 inches. Older varieties produce both males and females; the female plants produce red berries and can be slightly less vigorous.
Post-Planting Care For A Successful Bed
Correct spacing sets the stage, but ongoing care ensures your asparagus reaches its full potential.
Watering and Mulching Your New Planting
Consistent moisture is vital, especially in the first two years. Water deeply once a week if rainfall is insufficient. Apply a 4-inch layer of organic mulch, like straw or shredded wood, around the plants after the trench is filled. This suppresses weeds, retains moisture, and moderates soil temperature. Keep the mulch a few inches away from the emerging spears in spring.
Weed Control Strategies
Weeds are the primary competitor for young asparagus. Because the plants are widely spaced, weeds can easily move in.
- Hand-pull weeds carefully to avoid disturbing the shallow roots.
- Use a sharp hoe for the walking paths between rows.
- The mulch layer is your best defense, significantly reducing weed germination.
Fertilization Schedule
Feed your asparagus bed annually to support its heavy nutrient demands.
- Early Spring: Just as spears begin to emerge, apply a balanced fertilizer or one higher in nitrogen.
- After the Harvest: Once you stop cutting spears (around mid-June), apply another dose of fertilizer to support fern growth.
- Fall or Late Winter: A top-dressing of compost each year provides slow-release nutrients and improves soil structure.
Common Mistakes To Avoid With Asparagus Spacing
Even with the best intentions, gardeners can make errors that compromise their asparagus bed’s longevity.
Mistake 1: Ignoring Soil Preparation
Planting crowns in poor, compacted soil is a recipe for failure. No amount of correct spacing can compensate for a lack of deep, rich soil. The initial investment in soil amendment pays off for decades.
Mistake 2: Harvesting Too Soon
The greatest test of patience with asparagus is waiting to harvest. You must allow the plants to establish fully.
- Year 1: Do not harvest any spears. Let them all grow into ferns.
- Year 2: You may harvest lightly for 2-3 weeks.
- Year 3 and Beyond: You can begin a full harvest season of 6-8 weeks.
Mistake 3: Neglecting the Ferns
The ferny foliage that grows after the harvest is not just for looks. It is the engine of the plant, photosynthesizing and sending energy down to the crown for next year’s crop. Never cut down the ferns until they have turned completely yellow and died back in the fall. This is how the plant builds reserves.
Long-Term Maintenance Of Your Asparagus Bed
After the first few years, maintenance becomes simpler but remains important for sustained health.
Dividing and Renovating an Old Bed
If an older bed becomes overcrowded and production declines, you can dig up and divide the crowns in early spring before growth starts.
- Carefully dig up the entire clump.
- Use a sharp knife or shovel to divide the crown mass into sections, each with several healthy buds and roots.
- Replant the divisions immediately in a newly prepared bed, using the standard 18-inch spacing.
Seasonal Checklist for Asparagus Care
- Late Winter: Cut down and remove last year’s dead fern stalks before new spears emerge.
- Spring: Harvest, fertilize, and monitor for pests like asparagus beetles.
- Summer: Water during dry spells and ensure weeds are controlled.
- Fall: After ferns yellow, cut them down and add a layer of compost.
Frequently Asked Questions
Can You Plant Asparagus 12 Inches Apart?
While it is physically possible to plant asparagus crowns 12 inches apart, it is not recommended for a permanent bed. The plants will become crowded within a few years, leading to competition, thinner spears, and a potential decline in overall bed health and longevity. Sticking to 18 inches is the best practice.
How Much Asparagus Do You Get From One Plant?
A single, well-established asparagus plant (from one crown) can produce approximately 1/2 pound of spears per season over a 6-8 week harvest period. Yield increases as the plant matures, typically reaching full productivity around year 5 or 6.
What Is the Best Layout for Asparagus?
The best layout for a home garden is single rows spaced 4-5 feet apart, with crowns 18 inches apart within the row. This allows for easy access from both sides for harvesting and weeding. Some gardeners use a double-row system, with two trenches 18 inches apart and a 5-foot alley to the next double set, but this can make weeding the center more difficult.
How Deep Should You Plant Asparagus Crowns?
The initial planting depth for asparagus crowns is quite shallow. Place them in a trench so the top of the crown (where the buds are) is about 6 inches below the final soil surface. You then cover them with only 2 inches of soil initially, filling the trench in gradually as the plants grow during their first season.
Can Asparagus Be Grown in Raised Beds?
Yes, asparagus grows very well in raised beds, which provide the excellent drainage it requires. Ensure the bed is at least 12-18 inches deep to accommodate the deep root system. Spacing within a raised bed can follow the same 18-inch rule, but you may plant in a grid pattern since you won’t need wide walking paths between rows. Just ensure each plant has its allocated space.