Plant crowns November – January · Harvest spring, year 3 on · Phoenix / East Valley, AZ
Yes, you can grow asparagus in Phoenix, and right now is when you plant it. Asparagus is a perennial. You plant it once and it comes back every spring for years. The University of Arizona Cooperative Extension planting calendar for Maricopa County lists asparagus crowns from November through the end of January, so the job falls in the slow part of the gardening year.
The catch is patience: the real harvest starts in the third spring, and then the bed keeps producing every spring after that.
A quick note: I haven't grown asparagus in my own Gilbert garden yet, so I did some digging and pulled everything below from University of Arizona and University of California Extension research. If you've grown it here, I'd love to hear how it went.
UA Extension's Maricopa County calendar (publication AZ1005) marks asparagus for transplanting (crowns) at every planting date from November 1 through December 15, then again from January 1 through February 1. The "time to harvest" column for asparagus reads 2–3 years.
University of California guidance agrees: October through March is usually best for establishing a bed, and UC notes most nurseries carry 1-year-old crowns in the winter months.
One more thing to check: Extension says to plant after the soil reaches 50°F. A cheap soil thermometer pushed a few inches down tells you in seconds.
UA Extension's Yavapai County horticulture agent calls UC 157 probably the best variety for our climate. UA's "Vegetable Crops A to Z" adds that the University of California varieties like UC 157 are best adapted to our alkaline soils. UC 157 is also a main variety in California's low desert valleys.
You'll also see Jersey Giant, Jersey Knight, Jersey King and Mary Washington. Asparagus plants are male or female, and some hybrids are all-male, so they don't set seed that can turn weedy. If you can find UC 157, start there.
Local nurseries sometimes carry crowns in winter. If yours doesn't, this search shows mail-order UC 157 crowns. Buy the largest grade you can, and plant them soon after they arrive.
Search UC 157 crowns on Amazon →Affiliate link. I earn a small commission at no extra cost to you.
Most home gardeners plant crowns, the dormant root clusters sold in bundles. Nurseries label them "1-year," "2-year" or "3-year." UA Extension points out that they're all really one-year-old crowns grown from seed, just sorted by size. Bigger crowns have more vigor, so pick the largest, healthiest ones you can find.
Seed works too, but in the low desert UC says seedings take nearly two years to produce much. Crowns are the easier start.
This is the most important decision you'll make. UA Extension puts it bluntly: the bed "will be in that spot forever." Look for:
How much to plant: UA Extension says a 20-foot row or about 100 square feet of bed (about 20 crowns) is enough for a family of four, and a well-tended bed yields 8 to 10 pounds or more per 100 square feet.
Year 1: don't harvest anything. Let every spear grow into a fern. The ferns make the energy the roots store for next year's spears. UA Extension says to fertilize with nitrogen, keep the plants well watered, and keep 4 to 6 inches of straw, hay or leaf mulch on the bed to hold down weeds and keep the soil loose.
Year 2: just a taste. Each spring before spears come up, clear the old dead tops, weed, and fertilize. UA Extension's rate is 1.2 pounds of 5-10-10 per 100 square feet, with the same amount again in July. You can cut a few spears in year 2 (UC suggests a 3–4 week harvest at most, and less if the ferns were weak), then let the rest grow.
Year 3 and on: harvest for real. UC guidance is to cut daily or every other day for 8 to 10 weeks, then let the ferns take over for the rest of the year.
After harvest the bed turns into tall ferns. Your job is to keep them healthy through the heat:
Asparagus grows best between about 65°F and 85°F, and growth slows above 85°F, so expect the ferns to look tired in July and August. That's normal.
UC IPM explains that asparagus needs a growing period and a resting period. If cold or drought doesn't stop fern growth, the spears get spindly and weaker every year. With mild winters, water is the lever you control: UC's guidance is to stop irrigating in September or October so the ferns dry down and the plants go dormant.
Cut the ferns to the ground once frost browns them, or in January if they're still green, and rake them out. UC recommends throwing them away rather than leaving them on the bed, so pests don't overwinter in them.
Cut spears when they're 7 to 10 inches tall, slicing just below the soil line with a sharp knife. Spears get thinner as the season goes on. UA Extension's simple rule: never harvest a spear thinner than a pencil. Let those grow into ferns. If most of the spears come up thin, stop harvesting early that year. UC says that's the sign the plants are getting worn out.
Timing: spears start growing once the soil is above about 50°F. In California's low desert valleys, the commercial harvest season runs from December to early April. Warm weather makes spear tips open up early, which lowers quality, so plan on the spring heat ending your season.
Yes. UA Extension's Maricopa County calendar includes asparagus, and UC 157 suits Arizona's alkaline soils. The keys are a well-drained, weed-free bed, deep summer watering, and a fall rest.
In the Phoenix area (Maricopa County), UA Extension lists asparagus crowns from November 1 through February 1. Plant once the soil is at least 50°F.
Skip the first year, take only a few spears for a few weeks in year two, and start full 8–10 week harvests in year three.
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