Growing Asparagus From Seed
All About Asparagus
One of the few perennial vegetables, asparagus can produce annual springtime harvests for up to 20 years. Packed with flavor and nutrition, asparagus can be steamed, roasted, grilled and used in soups and other recipes.
Rich in antioxidants and nutrients, asparagus has many health benefits. It contains properties that: protect against cancer, heart disease, aging, inflammation, fungi, viruses, birth defects, osteoporosis, arthritis, hair loss, and depression; detoxify the body; and act as an aphrodisiac.
Asparagus takes two to three years to really produce an edible, strong crop--so growing asparagus is a lesson in patience. You do not get the swift satisfaction of planting a pole bean and watching it go from seed to harvest in two months. To successfully grow asparagus, a bit of research pays off. You will have the joy of eating a delicious batch of freshly steamed asparagus from your own yard if you choose your variety carefully, plant it in the right amount of sunlight, and start with disease-free roots, such as Gurney's selection of Asparagus Plants & Crowns.
Many asparagus varieties are available for home gardeners. Because asparagus plants are monoecious (each individual plant is either male or female), you might want to consider choosing a variety that is either all male plants or mainly male plants for asparagus growing. Male asparagus plants yield more harvestable shoots because they do not put their energy into producing seeds. Try Gurney's Jersey Supreme Hybrid Asparagus or Jersey Knight Hybrid Asparagus; both are all-male, high-yield varieties. For something a little different, especially if you are gardening with kids or grandkids, choose Purple Passion Asparagus. The stalks are larger and sweeter-tasting than most varieties and the purple color is intriguing (stalks will turn green when cooked).
How to Plant Asparagus Seed
While asparagus can be grown from seed, it takes at least three years to get from seed to harvest. Most gardeners choose to order one-year-old root crowns to start their asparagus garden. Because your asparagus plants are perennials, they will occupy a spot in your garden for up to 20 years. Select a location with this in mind. Here are some more asparagus planting tips:
- Select a site where the asparagus plants will receive 6-8 hours of direct sunlight daily. While some ask if asparagus can grow in the shade (it can tolerate some shade), it prefers full sun. Asparagus grows best in well-drained, sandy soil with a pH of 6.5 to 7. Very wet soils or areas with standing water will rot the roots. If you have clay soil, amend it with compost or aged manure to improve its drainage. Because asparagus is often planted in early spring, prepare the asparagus for planting in the fall. When considering how much space you need, take into account how far apart to plant asparagus. The general rule of thumb is 12-18 inches.
- If planting asparagus seeds, the asparagus seeds can be started indoors or directly sown in the prepared garden bed in the spring. Sow asparagus seeds 1 inch deep and 2-3 inches apart. Rows should be 12-18 inches apart. Asparagus seeds can take three weeks to germinate, so be patient.
- If planting asparagus crowns, prepare an 18-inch trench filled with 6 inches of compost followed by 6 inches of rich topsoil. Prior to planting, we recommend mixing Gurney's Asparagus Food into the soil.
- Soak the crowns in water for 20-30 minutes before planting.
- Spread the crowns over the soil and cover them with 2 inches of soil. If planting in the fall, fill the trench completely.
- When the spears emerge and are about 3 inches tall, add another two inches of soil. Continue doing this throughout the spring until the trench is filled and you have a slight mound above the soil line.
- A less time-consuming method is to fill the trench completely after planting. If the soil is too heavy, though, the spears may have trouble pushing through the soil and emerging. This method works best with sandy, loose soils.
- Once the plants have emerged and the trench is filled, a light mulch can suppress weeds and conserve moisture in the soil.
How to Grow Asparagus from Seed
Whether growing asparagus from seed or crowns, you generally have to wait two years or more before harvesting spears. During the first few years, focus on getting your asparagus plants off to a healthy, strong start. Here are some other tips for growing asparagus.
- Asparagus requires regular fertilization. We recommend using a plant food that is specific to asparagus, like our Gurney's® Asparagus Food. This slow-release fertilizer adds nutrients to the soil as needed.
- Each spring, apply 3-5 pounds of fertilizer per 100 square feet and work the fertilizer into the soil before growth starts. Repeat fertilizer application after the first harvest is complete.
- Check the makeup of your fertilizer to be sure your asparagus gets plenty of phosphorus and potassium. You can provide those nutrients by adding bone meal and wood ash to the soil. Pellet fertilizers are fine, but make sure you combine them with organic matter. A top-dressing of these materials after harvest and in the fall will help ensure good growth.
- Keep your asparagus bed free of weeds. A thin layer of mulch is one of the best ways to suppress weeds.
- After harvest, after asparagus flowering and through the fall, leave the asparagus plants alone. Let them just do what asparagus do naturally! If your asparagus turns yellow, don't worry, that's normal. Even as it yellows, the foliage is still feeding the plant, so don't cut it back until it totally dies back. At that point, usually in early winter, remove all remaining foliage. This will protect your plant from pests and diseases.
- In early winter, cut the tops back and add mulch to help prevent deep freezing and sudden changes in soil temperature.
Asparagus Care and Maintenance
Asparagus thrives in most grow zones that have winter ground freeze or dry seasons. The general exceptions are Florida and the Gulf Coasts. In addition to providing asparagus plants with fertilizer and water and keeping the area weed-free, you should also be on the look-out for common asparagus pests and diseases.
Pests and Diseases
The most common asparagus pest is the appropriately named asparagus beetle. They can feed on the spears, leaving brown scars or marks, or feed on the shoots, causing them to bend over like a shepherd's crook.
Cutting back the foliage in early winter helps control asparagus beetles. Other control methods include hand picking them off the plants and putting them in soapy water to kill them. Using beneficial insects or garden insect control are other options.
Common asparagus diseases include rust, fusarium wilt and crown rot. Selecting disease-resistant asparagus varieties helps control these.
The best protection against asparagus pests and disease is to keep your plants healthy and strong through feeding, weeding, and mulching.
How to Harvest Asparagus
Limit the first harvest to one or two cuttings by mid-June of the second year. A full crop can be harvested the third year after planting when the spears are 6-10 inches tall. If planting 2-year crowns, you should harvest a good supply the second year. Harvest for 6-8 weeks only, or until about the first of July in the North.
The spears are generally ready for harvest when they are 6 to 10 inches tall. Harvest the spears before flower buds at the tips begin to open. As the spears get taller, they get woody and less tender. Here's how to harvest asparagus in garden: snap or cut spears at ground level to avoid injuring new growth.
While growing asparagus is a lesson in patience, it pays off with a crop that returns year after year. The key to growing this perennial vegetable is to select and prepare a good site, to plant it properly and to put the care and time into the plants during the first few years. You and your family will be rewarded with tender spears for many years to come.