Asparagus Planting Guide

Asparagus Planting Guide

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Asparagus is a perennial vegetable that is best suited for cooler areas. It is grown for the spears, or the stem of the plant. A well-tended planting yields 8-10 lbs. per 100 square feet or 24 lbs. per 100 feet row. Asparagus plants can last up to 15-25 years if well cared for. It does not do well if summers are extremely hot and long and winters are mild. Asparagus is grown from either seed or from 2-year old roots. It takes 3 seasons from the time the seed is planted until you can harvest, and 1 season from the time the roots are planted to harvest. The best production occurs in its 6 and 7th year and continues to do well until the 12-15th year. After the 15th year there is approximately a 5% decline in yield every year after.

How do you plant asparagus?

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Asparagus prefers to be planted in deep, fertile, well-drained soil with Direct, FULL sunlight (7-8 Hours). They struggle in heavy clay soils, so it is essential to amend your soil for the best possible drainage, or to construct raised beds to alleviate the problem entirely. Make sure asparagus are planted in an area where the roots will not be disturbed. Be aware: asparagus roots can have up to a 40-50% loss when transplanted, even if done correctly and during the best planting season (March-April).

To plant transplanting roots, dig trenches 6-12 inches wide and 6-12 inches deep leaving rows 4-6 feet apart. Amend soil in the trenches with organic matter and a well-balanced fertilizer such as “That’s All it Takes” or Hi-Yield Bone Meal. To plant by seed, sow seeds directly into the soil ½ inch deep in April or May. Roots produce quicker and are most commonly planted in March and April. To plant from roots, place the root crowns 12-14 inches apart in the trench and cover with ONLY 4 inches of soil. Each time the asparagus stalks break through the soil, cover with another 2 inches of soil and continue this process until the trench is filled. Use Bush Doctor Kangaroots root stimulator for healthy and vigorous root systems. It will make your plants bigger, stronger and more productive if used 2-3 times per year for the first 2 years.

Varieties of asparagus

Here at Anderson’s Seed & Garden we sell 3 varieties: Jersey Giant asparagus as 2-year old roots and Mary Washington asparagus as seeds. These varieties produce large, dark green spears with good disease resistance and productivity. Purple Passion asparagus, another 2-year root, is another of our favorites – the lavender spears it produces are large, tender and absolutely delicious.

How often should you water asparagus?

Asparagus prefers infrequent, deep watering every 7-10 days. Make sure the top 1-2 inches of soil is dry in between waterings to prevent waterlogged soil, which can lead to root rot. Thick mulch may be applied around the roots to retain moisture and keep weeds out.

How should you fertilize asparagus?

Optimum pH is 6.5-7.0, which is slightly more acidic than what we have here in Cache Valley. Before planting asparagus, till in 2-3 lbs. of "That’s All it Takes" complete fertilizer per 20 feet of row. For established beds, scatter 1-2 lbs. per 20 feet row. In the fall, spread 2-3 inches of organic matter over the soil and work it into the soil carefully not to damage the established plants. It is essential that you fertilize and irrigate after harvest concludes in the late Spring to provide nutrient and water for the plants to recover.

Common problems with asparagus plants

Weeds and grasses are the most common problems in Asparagus. Keep the weeds pulled or hoed from the bed and use mulches to keep weeds from re-growing. You cannot spray asparagus with an herbicide during the first year. After the first year of true growth you can use a selective herbicide to control the grass, like Hi-Yield Grass Killer. It won’t affect the asparagus, but will kill all the grass that has invaded the plants. Aphids, asparagus beetles (which chew and twist spears), and rust beset asparagus plants. Choose varieties resistant to rust. Discourage beetles by removing all debris from the growing bed in fall, and knock or handpick the beetles off the asparagus plants and apply High Yield Garden Pet & Livestock insecticide, containing permethrin. Repeat applications as long as the beetles or larvae are feeding. Also treat in late summer and early fall to prevent the beetles from overwintering on the stems and re-infesting the next year’s crop below the soil surface.

When should you harvest asparagus?

Do not harvest the asparagus crop until after the first season if you have bought 2-year old roots, 3 years if growing from seed. Allow the unharvested spears to fern and to bush out. After these dry and turn brown, remove them.  A good general rule for harvesting asparagus is the 2-4-6 rule. Harvest for 2 weeks the second year, 4 weeks the third year, and 6 weeks the fourth and following seasons. There are a few different methods for harvesting asparagus. Cut the asparagus 1-2 inches below the soil. Or, snap the stems off right above the soil surface. To store asparagus, wash the spears and either store in water or in zip-lock bag in your fridge for a few days. Another method is to blanch the spears and store them in the freezer.

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