Asparagus is a long-term investment: a well-made bed can produce every spring for 15 to 20 years or more. It is a perennial vegetable grown from crowns, and it needs patience at the start, because you wait a couple of years before harvesting. In return, it needs little work once established. This page covers preparing the bed, planting crowns, care through the year and how to harvest spears.
Asparagus at a glance
| Type | Vegetable |
|---|---|
| Season | Perennial |
| Sun | Full sun |
| Plant spacing | 12 in |
| Row spacing | 48 in |
| Per square foot | 1 |
| Seed depth | 6 in |
| Days to maturity | Harvest from year 3 |
| How to start | Plant 1-year crowns in early spring in a trench; harvest lightly from the third year |
| Water | 1 in per week |
These are the same numbers our plant spacing, square foot and harvest date calculators use. See every crop in the plant database.
When to plant asparagus
Plant 1-year-old asparagus crowns in early spring, as soon as the soil can be worked, usually 2 to 4 weeks before your last spring frost. Asparagus needs a winter cold period to rest, so it grows best where the ground freezes or at least gets cool in winter.
Asparagus can also be grown from seed, but it adds a year before harvest. Find your dates with the frost dates by ZIP code tool.
How to plant asparagus
- Choose the spot carefully. The bed will be there for many years. Pick full sun at the side of the garden where the tall summer ferns will not shade other crops.
- Clear weeds thoroughly. Remove perennial weeds completely before planting; they are very hard to clear from an established bed.
- Dig a trench. Dig a trench about 6 to 8 inches deep and 12 inches wide, and work compost into the bottom.
- Plant the crowns. Set crowns in the trench at the spacing in the table above, roots spread out, and cover with 2 inches of soil. As spears grow during the first summer, gradually fill in the trench until it is level.
- Choose all-male varieties. They put energy into spears rather than seeds and give higher yields.
Caring for asparagus
Keep the bed weeded, especially in the first two years, and mulch to suppress weeds and hold moisture. Water about an inch a week in the first two years and during dry spells after that. The garden watering calculator turns this into gallons.
After harvest each year, let the spears grow into tall ferns. The ferns feed the crowns for next year, so do not cut them in summer. Cut them down once they turn brown in late fall or early spring. Feed with compost or a balanced fertilizer each spring and again after harvest ends.
Companion plants
| Grow nearby | Tomatoes, parsley, basil, marigolds, strawberries |
|---|---|
| Keep apart | Onions and garlic; potatoes |
Tomatoes and asparagus are a classic pairing: tomatoes are said to deter asparagus beetles, and asparagus is said to discourage root nematodes that attack tomatoes. Parsley and basil grow well alongside. Check other pairings with the companion plant finder.
Common problems
| Problem | What you see | What to do |
|---|---|---|
| Asparagus beetle | Spotted beetles and gray larvae on spears and ferns | Hand-pick beetles and larvae, and clear old ferns in fall to remove overwintering sites. See the pest identifier. |
| Thin spears | Spears are pencil-thin and few | Crowns are weak or overharvested. Stop harvest when spears get thin, let ferns grow all summer and feed the bed. |
| Fusarium crown rot | Weak, yellowing plants and reddish-brown crowns | Plant healthy crowns of resistant varieties in well-drained soil. Do not replant asparagus in an old bed. |
| Rust | Orange or rust-colored spots on ferns | Grow resistant varieties, space for airflow and remove infected ferns in fall. |
| Weeds | Grass and weeds crowding the bed | Clear weeds before planting and keep the bed mulched. |
Not sure what you are looking at? The plant problem identifier ranks likely causes from the symptoms you see.
When and how to harvest
Do not harvest in the first two years after planting crowns, so the plants build strong roots. In the third spring, harvest for 2 to 4 weeks. From the fourth year on, harvest for 6 to 8 weeks each spring, stopping when most new spears are thinner than a pencil.
Pick spears when they are 6 to 8 inches tall and the tips are still tight. Snap them off at the point where they break naturally, or cut them just at the soil surface. In warm weather, spears grow fast, so check daily. Stand spears upright in a little water in the fridge and use within a few days.
Plan your asparagus
- Plant spacing calculator: how many plants fit your bed
- Planting calendar: sowing and transplant dates for your frost dates
- Frost dates by ZIP code: your last spring and first fall frost
- Harvest date calculator: when your crop will be ready
Frequently asked questions
How far apart should I plant asparagus?
Space asparagus 12 inches apart in rows 48 inches apart. In a square foot garden, plant 1 per square foot.
How deep do I plant asparagus crowns?
Plant 1-year-old crowns about 6 inches deep in a trench, with the roots spread out. Cover with 2 inches of soil, then fill the trench gradually as the spears grow.
How long does asparagus take to grow?
Asparagus planted as crowns is harvested lightly from the third spring, then for 6 to 8 weeks each spring from the fourth year. A bed can produce for 15 to 20 years or more.
How much water does asparagus need?
About 1 inch of water a week, from rain and watering combined. Water regularly in the first two years and during dry spells after that.
Should I cut back asparagus ferns?
Not in summer: the ferns feed the crowns for next year. Cut them down once they turn brown in late fall or early spring.