Asparagus is delicious. The spears are also expensive. The stalks you buy at the store are usually shipped long distances and can’t compare to what you’ll harvest from your own garden. While asparagus has a reputation for being hard to grow, that’s mostly myth. They just take their sweet time before producing edible spears—but when crowns last 15 to 25 years, that patience pays off!
How Much to Plant
Asparagus plants are either male or female. It’s the spears (stems) that gardeners crave. Male plants are more productive because they don’t spend energy making seeds. All-male varieties or hybrids help ensure bigger yields. For a family of four, 20 crowns planted in a 20-foot row will provide plenty of asparagus each season.
Prepare the Bed Well
Since asparagus is a true perennial, place it in an area where it can grow undisturbed for decades. Pick a spot with full sun, and avoid areas where shade-loving weeds might encroach. In fall (before planting), dig in 3 inches of compost or well-rotted manure to the top 10–12 inches of topsoil and remove all perennial weeds. Test the soil’s pH—ideally, you want it at 6.5–7.5, as asparagus prefers neutral to slightly alkaline conditions. Apply lime months ahead if needed (December in the Northern Hemisphere/June in the Southern Hemisphere), since lime takes time to raise the pH.
Planting Asparagus
Plant dormant, healthy one-year-old crowns in early spring, as soon as the soil can be worked and after all major weed pressure is eliminated. Dig a furrow 6–10 inches deep and about 12 inches wide (deeper for heavy soils, shallower for loamy soil). Sprinkle a phosphorus-rich fertilizer (such as superphosphate or bone meal) directly in the trench, using about ½ pound per 10-foot row. Using the soil you removed from the trench, make hills of dirt that are 2-3 inches tall. Place crowns 12–18 inches apart, spreading out roots over the small hill of topsoil in the base of the trench. Do not let the roots touch the fertilizer. Cover with 2–3 inches of soil, then water in thoroughly.
Fill In the Furrow Gradually
As shoots emerge, gently fill in more soil around the plants, keeping shoot tips exposed, until the trench is level with the ground by the end of the first season. Consistent weeding early is critical: asparagus does not compete well with weeds, and weed pressure will reduce vigor and lifespan.
Once the trench is filled and the spears are four inches tall, mulch 2–3 inches deep to insulate roots, suppress weeds, and conserve moisture. Do not let the mulch touch the stems. Leave an inch collar of mulch-free space around the spear.
Fertilizing
Apply a balanced fertilizer (such as 10-10-10) before spears emerge in late winter to early spring—about 2 pounds per 20 feet of row, or according to your soil test recommendations. After harvest, side-dress with nitrogen (21-0-0) to promote strong ferns. Each year, add a few inches of compost in early spring to nurture crowns and soil health.
Watering
Asparagus roots run deep, but good production depends on regular water, especially during the establishment years. Provide about 1–2 inches of water per week during active growth, soaking the whole root zone. Don’t let soil get soggy, but never let it become bone dry either. Deep watering encourages crown development and hefty spears.
Harvesting
Begin light harvesting in the third season after planting crowns. Harvest spears when they are 6–8 inches tall and still tightly closed at the tip—larger spears tend to get tough. Cut or snap spears at ground level (not higher or lower). Stop harvesting when spear diameter decreases to pencil size or tips start opening. Let all remaining shoots “fern out” to replenish the crown for next year.
Preparing for Winter
Once the ferns yellow and die back after frost, cut them down to 2-inch stubs and mulch with compost or aged manure. Remove or compost ferns away from the bed to prevent pests from overwintering. Maintain a weed-free, mulched bed year-round for the healthiest plants.
White Asparagus
White asparagus is grown by mounding soil or mulch over the spear as it grows, Keep spears in total darkness while they emerge, preventing chlorophyll development. This blanching yields mild, tender spears, but requires regular effort to cover growing spears
Free Asparagus growing checklist download
Tip: For full, step-by-step details, see our dedicated All About Growing Asparagus guide.
If you have gardening questions, book a call or email me at stephanie@allaboutgardeningguides. I charge $25 for up to 15 minutes.
