Asparagus is a perennial vegetable. Plant it once, and a healthy bed can feed you every spring for 15 to 20 years or more. It is one of the first crops of the year, ready when little else in the garden is.
The catch is patience. You need to wait two to three years for a full harvest. The roots need time to build up the energy to send up spears year after year.
When to plant asparagus
Plant asparagus crowns in early spring, as soon as the soil can be worked. Crowns are one-year-old roots, and they are the easiest way to start a bed. You can grow asparagus from seed, but it adds a year before your first harvest.
Where to plant asparagus
Choose your spot with care, since the bed will be there for many years.
- Full sun, at least 6 to 8 hours a day
- Well-drained soil, since asparagus roots rot in wet ground
- A soil pH of 6.5 to 7.0
- A spot at the edge of the garden, where tall summer ferns will not shade other crops
Clear out all weeds before you plant. Grasses and other perennial weeds are the hardest to remove later. Asparagus does not compete well with weeds, and they are hard to pull from an established bed.
How to plant asparagus crowns
- Dig a trench about 12 inches (30 cm) wide and 6 to 8 inches (15 to 20 cm) deep.
- Work compost into the bottom of the trench.
- Make a low mound of soil down the center of the trench.
- Set the crowns on the mound 12 to 18 inches (30 to 45 cm) apart, with the roots spread out down the sides.
- Cover the crowns with 2 inches (5 cm) of soil and water well.
- As the spears grow, keep filling in the trench a little at a time, until it is level with the ground by late summer.
Space rows 3 to 4 feet (1 to 1.2 m) apart.
When to harvest asparagus
| Year | What to do |
|---|---|
| Year 1 | Do not harvest. Let all the spears grow into ferns. |
| Year 2 | Harvest a few spears for 2 to 3 weeks, then let the rest grow. |
| Year 3 and on | Harvest for 6 to 8 weeks each spring. |
Pick spears when they are 6 to 8 inches (15 to 20 cm) tall and the tips are still tight. Snap them off at the soil line, or cut them a little below the soil with a sharp knife. In warm weather, spears grow fast, so check the bed every day or two.
Stop harvesting when most new spears are thinner than a pencil. That is the sign the roots need to rest and rebuild.
Caring for the ferns
After you stop picking, let the spears grow into tall, feathery ferns. Do not cut them. The ferns make food for the roots, and that food becomes next year’s spears.
In late fall, once the ferns turn yellow or brown, cut them down to the ground. Remove the old ferns from the bed to cut down on pests and disease.
Feeding and weeding
- Spread compost or well-rotted manure over the bed each spring.
- Mulch with straw or shredded leaves to keep weeds down and hold in moisture.
- Pull weeds by hand. Do not dig deep, since asparagus roots grow close to the surface.
- Water during dry spells, more in the first two years.
Best asparagus varieties
| Variety | Notes |
|---|---|
| ‘Millennium’ | Male hybrid, bred in Ontario, good for cold climates |
| ‘Jersey Knight’ | Male hybrid, high yields, disease resistant |
| ‘Jersey Giant’ | Male hybrid, thick spears |
| ‘Purple Passion’ | Purple spears that turn green when cooked |
| ‘Mary Washington’ | Heirloom, reliable, mix of male and female plants |
Male plants produce more spears. Female plants put energy into red berries and drop seeds that turn into weedy seedlings.
Common asparagus problems
- Asparagus beetles chew spears and ferns. They are small, with orange or red and black markings. Hand-pick beetles and wipe off the dark eggs on the spears.
- Thin spears mean the roots are tired. Harvest for a shorter time next year and feed the bed well.
- Crooked spears can come from beetle damage, wind, or frost.
- Weedy beds are the most common reason asparagus fails. Keep up with weeding and mulch.
More perennial crops
Asparagus pairs well with other crops you plant once and pick for years:
Looking for the houseplant? Asparagus fern is a different plant and is not edible.
Seed companies I like
These are the seed companies I order from for my own garden.
- Botanical Interests: beautiful packets with growing notes printed inside
- High Mowing Organic Seeds: certified organic, grown in Vermont
- True Leaf Market: big selection of hybrids, microgreens, and cover crops
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