Growing asparagus is a labor of love as it takes multiple years before a decent harvest is achieved. Once the plants become well established you can expect a harvest of delicious and tender spears every year for the next 15 years or more. It's important to incorporate perennial vegetables into your garden design because they don't require constant soil disturbance like annuals. Maintenance usually consists of keeping the area weed free, mulching if necessary, and applying a good layer of high quality compost every year.
Site selection for asparagus is very important because the plants can grow and be productive for 15 years. Asparagus prefers loose, well-drained soil, with a pH around 6.5 to 7. Adding lime to the soil will benefit the asparagus greatly if you live in a region with very acidic soil such as the river valley of Western Oregon. Keep the asparagus bed well weeded and top with well-aged compost every year.
Most growers don't grow asparagus from seed because of the amount of time it takes to develop mature plants. We enjoy planting asparagus from seed because there are more varieties to choose from and it is very easy to do. Start seeds 12 weeks before the average last frost. For Western Oregon this is around the beginning of February. Plant seeds in a 72 or 96 cell tray, covering seed with 1/2" of soil. Keep seeds at 75 during the day, and 60 degrees at night. Germination should occur within 2 weeks. Plant outside in a "W" shaped furrow after all danger of frost has passed. Plant the seedlings in the middle of the "W" to assure good drainage for the roots. Gradually fill in the furrow as the plant grows.
Some seed companies offer dormant asparagus crowns that are two years old and have well established roots. Asparagus crowns can be planted earlier in the season, about 4 weeks before the average last frost date for your region. Dig a 6" deep and 6" wide furrow and place the crowns in at an 8" to 10" spacing. Spread the roots outward within the furrow. Cover the roots and buds with 3" of soil. As the spears emerge in spring continue to fill in the furrow until it is completely filled in.
Whichever planting method you choose it is important to not harvest any spears the first year of planting. Allow the fern-like fronds to grow and only cut them back once they have turned yellow in early winter. If you started your asparagus from seed, you will need to allow the leaves to grow without harvesting in the 2nd year as well. In the 3rd year, or the 2nd year if you planted crowns, harvest spears for about 2 weeks and then let the plants grow again. Gradually increase your harvest time each year as the plants get well established. You can harvest for 6 weeks each year when the plants have been planted for 3 or more years. Harvest the spears by cutting them off just below the soil surface when they are 6" to 9" long.
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