The Long Wait for Asparagus

Seven hundred and thirty days until harvest. Two full years may seem like a mind-numbing length of time to wait. But consider that the result will be 15 to 20 years of fresh, tender asparagus, and all is forgiven. Although asparagus is harvested in the spring, winter is the time to select and to plant.

Asparagus is a perennial crop, and one of the few perennial vegetables that we grow. It’s typically planted bare-root in January and February, at the same time that bare-root fruit trees and roses go into the ground. Each plant is dormant and little more than a clump of roots.

Growing your own asparagus results in amazingly succulent spears. It also provides cooks with an opportunity to play with color. While most commercial asparagus is a rich green, in the garden you can fiddle with purple and white spears.

What to Select

Previous generations of home gardeners were limited to asparagus that had been created by East Coast breeders to withstand freezing winters and wet, humid summers. Names like Mary Washington, which was introduced in 1917, and Jersey Giants may come to mind.

But those varieties don’t perform as well on the West Coast. So researchers at UC Davis and UC Riverside developed asparagus plants that embrace mild winters and produce heads that don’t open with warming temperatures in spring.

Today, the gold standard for our climate is UC 157. It produces double the crop of Mary Washington, matures earlier and maintains tight heads.

Availability can be spotty. But with an asparagus bed lasting up to two decades, UC 157 is worth the hunt.

Purple asparagus is on the rise as well. Purple Passion was developed in Northern California by Brian Benson, who also created UC 157. Pacific Purple is a newcomer from New Zealand.

Neither produces yields as bountiful as UC 157. But the purples have a higher sugar content and are said to taste a little sweeter. And the spears are less fibrous, so you don’t snap off as much of the stalk prior to cooking. They do, however, turn green with heat.

As for white asparagus—it’s not a separate variety. Instead, the white results from a technique called blanching. Cover the emerging tips of green or purple asparagus with shredded leaves, peat moss or even plastic nursery pots to prevent sunlight from reaching them. This prevents the plants from producing chlorophyll, which normally turns the spears green or purple. That’s why if you dig around, you’ll see that below the surface the stems are white.

At Planting Time

Your asparagus is in this for the long haul, so don’t skimp on prep.

You’ll be planting the asparagus roots—AKA crowns—in long trenches. Loose, fertile soil is a must. Raised beds are ideal. Otherwise plan to build a few substantial berms.

Choose a spot that gets at least six to eight hours of daily sunlight. Asparagus needs sunshine to warm the soil when the slumbering roots begin to stir after the winter solstice.

The site may be within your vegetable garden or along a fence or wall where the asparagus’ ferny foliage can provide a filmy backdrop for ornamental plants. Strawberries should not have been grown there. They may have tainted the soil with rust, which can infect the asparagus.

Dig a trench one foot wide and eight to 10 inches deep. A dozen crowns—enough to feed a family of four—require a trench about 12 feet long, or two trenches six feet long spaced several feet apart.

Amend the soil that you’ve removed with a generous amount of organic material, such as compost, leaf mold, well-rotted animal manure, earthworm castings or peat moss.

Use the amended soil to shape a two-inch-tall mound of the amended soil down the length of the trench. Water thoroughly. Spread the spidery roots of each crown on top of the mound, spacing the crowns one foot apart. Add another two inches of amended soil, then water again.

Keep the bed moist. In a month or so, pale shoots should appear.

Let those tips grow an inch or two tall. Add soil, but don’t cover the tips. Chase the growth, adding soil bit by bit as the tips rise. But don’t bury the tips. They may rot if they don’t see the light of day.

Filling the trench may take a month or more. Continue to water regularly. As summer progresses, the tips will open, then produce tall, feathery, fern-like branches. In the fall, the foliage will yellow, while female plants produce red berries.

Wait to cut down the ferns until they’ve turned brown and begun to wilt. This allows the plants time to build up reserves of carbohydrates in their roots. More carbs translates to more vigorous roots and more prolific harvests.

The first spring after planting, harvest only one or two spears from each plant. Taking more will deplete the roots’ energy and subsequent crops.

The spears are ready when they reach six to eight inches high. Use a sharp knife to slice off the stalks at an angle just below the soil line. Cutting them flat may nick neighboring stems.

The Second and Third Spring

The second spring after planting, harvest any spears that are at least the diameter of a pencil.

By the third spring, new spears may be ripe every day of the season.

If you miss a few days and the tips open, don’t harvest those spears. Instead, let them leaf out. Stop the harvest completely when new spears decrease in size.

Keep the bed well watered year-round. Even if nothing is happening above ground, the roots need moisture to flourish.

After the annual trim, apply an inch or two of well-aged, fine-textured compost or other organic material to replenish nutrients and keep down weeds.

Your maintenance and patience has paid off, as you look forward to 15 to 20 years of fresh, tender asparagus.