Planting Asparagus and Heirloom Varieties

Planting asparagus in a raised bed or in the backyard vegetable garden will pay dividends for years and years to come.


| March/April 2016



Asparagus

With older types of asparagus, a routine practice was to plant extra plants, and when it became evident which plants were females, rogue them out.

Photo courtesy Baker Creek Heirloom Seeds; www.RareSeeds.com

I love looking at the delicate beauty and play of light filtering through fine-leaved asparagus stalks in summer, especially as a backdrop to bolder-leaved plants and flowers. Few gardeners cultivate asparagus for this purpose, and it’s an added bonus to its springtime bounty of weird-looking edible spears.

Asparagus holds an almost unique position in the vegetable garden by being the only green vegetable in temperate climates which is routinely cultivated as a perennial crop. There are a host of other minor perennial vegetables and herbs – for example Jerusalem artichoke (Helianthus tuberosus), sea kale (Crambe maritima) or Chinese artichoke (Stachys affinis) – but none have the wide appeal of springtime asparagus. Because it is a perennial, it requires its own unique space, one that can serve as a relatively permanent bed for 20-plus years. It is a plant that enjoys solitude, disliking any weed competition or companion plants.

One key to great asparagus yields is an extremely well-prepared site. The new bed should be weed free, especially of any perennials, so depending on your situation, you may need to prepare the bed up to a year in advance. Asparagus generally prefers full sun. Covering the area with cardboard, organic mulch or black plastic can be helpful in smothering weeds. Asparagus prefers a fertile, reasonably well-drained, loamy soil. In most situations, very generous additions of compost, leaf mold and/or rotted manure are required. Since asparagus is a “permanent” crop, the investment of time and money is worthwhile.

When planting, incorporate a granular organic fertilizer for its long-term benefit. Rock phosphate is a beneficial source of slow-release phosphorus. If you have dense, clay soil, additions of sand, fine gravel, granite dust or greensand may be helpful.

The bed is often dug as a trench to a depth of 18 inches, and then backfilled. While asparagus requires adequate moisture, a well-made bed situated in a clay envelope can retain too much moisture, thus reducing aeration if there is insufficient drainage away from the bed. Raising the bed can help in dense soil conditions. Building a raised box may be an easier solution than deep digging, especially in heavy soil. The bed’s productive life will likely outlast your wood frame, which will need replacement at some point.

In its native habitats, asparagus is found growing in moist places and seashores, and is tolerant of saline conditions. You may have noticed wild asparagus growing in less than ideal sites. While it can grow in a variety of terrains, if you want good yields, you should optimize your growing conditions. Some old-timers say that additions of salt to the asparagus bed will help kill weeds. Because asparagus is salt-tolerant while other plants are not, this works in principle. I don’t recommend it, however, because it can harm the soil.





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