How to Grow Asparagus in Arizona

When people visit my garden in spring, I ask if they know how asparagus grows. Most of them don’t. So I find a spear coming up out of the soil, pluck it off, and hand it to them to try. Raw and straight from the garden, it’s delicious.

You can grow asparagus in Arizona. I’ve grown it in my Mesa garden for more than 10 years, all from crowns. It’s a long-term crop. You wait a couple of years for your first real harvest, and then the same plants come back every spring. This fall I dug up my bed and replanted it, so I’ll also share what went wrong after a decade and what I changed.

How Asparagus Grows

Asparagus is a perennial. The spears you eat are new shoots coming up from an underground crown. In spring, I harvest the spears. Once I stop harvesting, the rest of the spears grow into tall, feathery ferns. Those ferns feed the roots through summer and fall, and that stored energy produces next spring’s spears.

In winter, the ferns turn yellow and the plants slow down. In a mild winter, mine sometimes stay green. Either way, I cut them back before spring growth starts.

Plan on two to three years before a full harvest. After that, a healthy bed produces for 10 to 15 years. Mine went a full decade before it needed attention.

Where I Grow Asparagus

Asparagus stays in one place for years, so choose the spot carefully. Good sunlight is essential. Mine grows in full sun, and it handles our summers fine. The soil needs to drain well, because crowns sitting in soggy soil can rot.

If you have heavy clay, a raised bed is the easier route. My post on the best soil for raised bed vegetable gardening covers what to fill it with, and these tips on choosing a raised bed garden location help you find a sunny spot.

Asparagus usually grows best in a bed of its own. The ferns grow tall in summer, so think about what’s next to that bed. In the right spot, you can use them to shade other crops during the summer.

Asparagus Crowns or Seeds?

I started my bed from crowns, and that’s what I recommend. Crowns are 1 to 2 year old asparagus roots. They give you harvestable spears about a year sooner than seeds. Seeds cost less, but you’ll wait at least two years before harvesting.

I don’t know which variety my crowns are. Jersey Knight and Martha Washington both do well in the low desert. All-male varieties such as Jersey Giant, Jersey Knight, and Jersey Supreme put their energy into spears instead of seeds, so they tend to produce larger spears. Purple Passion is a good choice if you want purple spears.

When to Plant Asparagus in Arizona’s Low Desert

Plant asparagus crowns from November through January. You can find crowns online and at local nurseries during that window. My guides on what to plant in November in the low desert and what to plant in January in the low desert list what else goes in at the same time.

If you’re starting from seed, start seeds indoors from August to November. Sow them ½ inch deep. They take about 30 days to germinate. Move the seedlings into the garden from November to January, once they’re about 3 inches tall. My post on how to start seeds indoors has the steps.

In colder climates, plant crowns in early spring when soil temperatures reach 50ºF.

How I Plant Asparagus Crowns

Dig a trench about 6 inches deep. Set the crowns in the trench about 12 inches apart, with the roots spread out and the buds facing up. Cover them with about 2 inches of soil and tamp it down gently. I don’t soak my crowns before planting. They go straight into the trench.

As the spears grow, add about 2 inches of soil every two weeks until the trench is filled back to the level of the bed. Stop there. When I dug up my bed this fall, my crowns were buried much deeper than they started. More on that below.

How Long Before You Can Harvest Asparagus?

The first couple of years take patience. Those early ferns build the root system that feeds you for the next decade.

If you start from seed, add another year before your first harvest. Only harvest spears that are at least ¼ inch thick, about the thickness of a pencil. Leave thinner spears to grow into ferns.

How I Harvest Asparagus

My spears start coming up in spring. During harvest season, I check the bed every few days and pick spears that are 6 to 10 inches tall with tight, firm tips. I pluck them off at the soil line. You can also cut them just below the surface with an asparagus knife.

Late spring heat slows everything down. Once the spears turn woody and the tips start opening before they reach full height, I stop harvesting and let the rest grow into ferns. My guide to spring gardening in Arizona covers what else is happening in the garden then.

My Asparagus Year, Month by Month

Here’s what my asparagus bed looks like through the year.

I water my asparagus on the same schedule as the rest of my garden, and it doesn’t need anything special in summer. My post on the best way to water raised bed gardens explains how I set that up. Once a year, I add a light layer of compost and a light layer of mulch. For feeding, I use a balanced organic fertilizer. I don’t use Epsom salt on my asparagus. Here’s my list of the best organic garden fertilizer options.

When I cut back the ferns, I cut them off at soil level. If they’re free of pests and disease, I use them as mulch on the bed. Wood chips or straw work too. Then I water the bed well. A dormant bed doesn’t need much water, but don’t let it dry out completely. This video shows how I cut back my asparagus bed for winter.

I used to add a thick layer of manure, as you’ll see in this video. After my crowns got buried, I switched to a light layer once a year.

What Happened to My Asparagus Bed After 10 Years

After about 10 years, I noticed my asparagus wasn’t growing as well as it used to. The bed was a hot mess.

This fall I dug down to find out why. The crowns had gotten too buried. I think I’d covered them too much over the years. I dug the crowns out, thinned out the plants, and replanted them in the same bed. Things are already growing better.

If an older bed is slowing down, check how deep the crowns are before you give up on it. Each layer of compost and mulch you add on top raises the soil over the crowns. Now I add one light layer of each once a year, and I check the depth every few years. I share more lessons like this in my post on raised bed mistakes.

Asparagus is one of the edible perennials in my desert garden. It takes patience to get started, but once it’s established, it comes back every spring.

Growing Asparagus FAQs