How to Grow Asparagus and Keep It Thriving for Decades, According to Experts

Perennial vegetables are an elite group and are prized for their ability to produce a harvest year after year. Asparagus is one of these valued veggies, and, best of all, it's very easy to grow.

Like any vegetable, there are some important care instructions and considerations that you should know before planting asparagus. Here, we spoke with experts and gathered the best tips for a successful and delicious crop.

Types of Asparagus

Several varieties of asparagus are available on the market, ranging from heirlooms to hybrids and in colors such as green, purple, and more.

The Jersey series of asparagus, for example, has been discontinued despite its popularity, although it may still be possible to find it at certain garden centers and suppliers. Millennium is a hybrid that's gained popularity in the wake of the Jersey series. If you're interested in open-pollinated varieties, however, then you can't go wrong with the green Mary Washington or the violet Purple Passion. 

Planting 

Most experts recommend growing asparagus from a crown, which is a small root ball with sprouts and a long, trailing root system. It resembles a tiny octopus. 

Planting crowns is a bit like planting potatoes. Do it early in the spring, as soon as the soil is free of frost. It's usually advisable to dig a long trench, approximately 8 inches deep, and place your crowns in that trench with the sprouts facing up and separated by 12 inches or more.

You can refill the trench completely and bury the asparagus crowns under the full 8 inches of soil; you can also lightly cover the crowns with only a couple of inches of soil. Then wait until the asparagus shoots have sprouted about 2 inches high, add more soil, and repeat the process slowly until the trench is full.

Asparagus can also be planted from seeds, although this takes longer. If you decide to go this route, plant the seeds in the spring, about an inch deep, and keep weeds at bay during the tender first year. You can grow your initial seedlings in any location you'd like, and then dig up the crowns and move them later.

Care Requirements

Taking care of asparagus is all about providing the proper conditions, from water and light to soil and fertilizer.

Water

Asparagus doesn't have intense watering needs–about 1 or 2 inches of water per week will typically suffice.

Soil

Asparagus prefers soil with plenty of organic matter and that's well-drained, with an almost sandy-loam consistency. 

Fertilizer

Fertilization is usually needed prior to planting, but a soil test can help you determine nitrogen, phosphorus, and potassium levels. Fertilizing established beds in later years is often not necessary. 

Sun

Like many vegetables, asparagus does best if planted in full sun, where it can receive that critical six to eight hours of direct sunlight per day. 

Temperature

Asparagus grows well in summer daytime temperatures of about 70 to 80 degrees Fahrenheit. It thrives in climates with a definitive dormancy period and cold temperatures.

Harvesting

You can harvest the spears from established asparagus plants when they're about 8 inches tall. "Select a few spears while they're still under 12 inches and snap them off at the base where they naturally break," says gardening author Kathy Jentz. You can harvest as quickly as they produce—it's better than letting the shoots get too tall.

Partway through the growing season, you'll want to stop harvesting the spears and allow them to grow their wispy foliage for photosynthesis.

Ultimately, your established asparagus bed can produce veggies for 15 or 20 years. "Yes, digging an asparagus bed takes effort. Yes, gradually filling in the soil over the newly planted asparagus crowns [can take] weeks," says master gardener Charlotte Germane. "But when your work is done, you'll have homegrown asparagus stalks so delicious that you may find yourself eating the freshly-picked spears while standing next to the asparagus bed."

Common Mistakes

Asparagus are very easy to grow, but there are a few mistakes that experts see happen more often than not. Here's what they are, and how to avoid them.

Overharvesting

"The biggest mistake folks make when growing asparagus is to over-harvest it," says Jentz. "During its first few years, you need to not harvest any spears. Then, in the third year of growth, you can start to harvest up to half of the spears."

Ignoring Pests

Asparagus doesn't require much maintenance, but you should watch out for pest damage. "The most common insect that attacks asparagus is the asparagus beetle," says Jentz. "To prevent them, eliminate the asparagus foliage once it dies back in the late fall and dispose of it—as that's where this beetle overwinters."

Ignoring Weeds

If there's one thing asparagus dislikes, it's weed competition. Plan on keeping the beds weed-free— this is especially important during the early years, when the crowns are establishing.