Tall Asparagus Plants: How to Train Them for 6-Foot Spears

Growing a tall asparagus plant means transforming your garden into a lush, productive forest of spears—some reaching 6 feet or higher with the right care.

Imagine harvesting asparagus spears that tower over your head—taller plants mean bigger yields and fewer harvests. But growing asparagus to 6 feet isn’t just luck; it’s science, technique, and patience. Here’s how to train your asparagus crowns to reach their full potential while avoiding common pitfalls.

Most gardeners stop at the standard 3-5 foot range, but varieties like Mary Washington or Purple Passion can soar higher with the right soil, spacing, and support. The key? Start with well-drained, nutrient-rich soil and give each plant 18 inches of space to stretch upward.

In this guide, you’ll learn how to stake your asparagus, prune for vertical growth, and avoid the mistakes that keep spears short. Ready to turn your garden into a towering asparagus grove?

How to grow tall asparagus spears: soil, spacing, and support techniques

Tall asparagus plants aren’t just a novelty—they’re a game-changer for your garden. A 6-foot asparagus plant produces 3x more spears than a 3-foot variety, and with the right techniques, you can train your plants to reach their full height potential.

The secret lies in three foundational elements: soil quality, proper spacing, and structural support. Skip any of these, and your spears may flop instead of flourish.

First, let’s address the elephant in the garden: most asparagus varieties max out at 3-5 feet without intervention. But with Mary Washington or Purple Passion varieties—and the right care—you can push them closer to 6 feet.

The key is starting with a nutrient-rich soil that drains well, spacing crowns 12-18 inches apart, and adding support early to prevent lodging (when plants topple under their own weight).

Here’s the summary-table breakdown of what tall asparagus plants truly need to thrive:

Let’s start with the soil—this is where 90% of your tall-asparagus success begins. Asparagus roots spread deep and wide, so you need soil that’s loamy and well-draining. Amend your garden bed with aged compost or well-rotted manure to a depth of 12 inches.

A pH between 6.0 and 7.5 is ideal; test your soil and adjust with lime (to raise pH) or sulfur (to lower it) if needed. Clay-heavy soil? Mix in sand or perlite to improve drainage—waterlogged roots are a fast track to stunted growth.

Next, spacing is everything. Crowded asparagus plants compete for nutrients, leading to weak, spindly spears that never reach their full height. Space 1-year-old crowns 12-18 inches apart in rows that are 3 feet apart.

Plant them in trenches 8-12 inches deep—this encourages roots to grow downward, creating a stronger anchor for tall growth. Pro tip: Plant crowns perpendicular to the row (like a ladder) to maximize airflow and reduce disease risk.

Now, let’s talk support systems, because without them, your 6-foot dreams will turn into 3-foot flops. Asparagus ferns can get top-heavy, especially in windy conditions. Install bamboo stakes, wire cages, or trellises when spears reach 3 feet tall.

For Mary Washington varieties, use 3-foot stakes placed 6 inches from the crown and tie ferns loosely with soft twine to avoid damaging stems. If you’re growing in a windy area, opt for cages made of chicken wire—they’re sturdy and allow spears to grow freely.

Timing is critical when it comes to planting and spearing. Plant 1-year-old crowns in late winter to early spring, about 4-6 weeks before your last frost date. In Zone 6a, that’s typically March. Avoid planting in summer heat, as crowns struggle to establish roots.

For the first 2 years, resist the urge to harvest spears—let the plant focus on building a strong crown. Starting in year 3, you’ll see spears reaching 6-8 inches