Growing Asparagus from Seed

by admin | May 22, 2019 | Gardening

One year when I was homeschooling my granddaughter in the 9th grade, we planted asparagus from seed in January to see if we could get asparagus more economically than paying for asparagus roots.  The kitchen windowsill was crowded with 25 seedling starts. We decided to order 25 Jersey Giant roots as we wanted to see which might perform the best over the years, our seedlings or the nursery roots.

  One of the few perennial vegetable crops, asparagus comes back year after year, producing pounds of succulent spears for 15 to 20 years or more. In fact, when it comes to productivity, asparagus is difficult to top. A modest planting of 25 all-male crowns (dormant roots) will yield up to 20 pounds of edible spears per year.  We were aiming for 50 plants as it was recommended that 25 plants would provide a year’s supply of asparagus for one person, and we were a two-person household that enjoy asparagus.

Asparagus plants (Asparagus officinalis) are unusual because they’re dioecious, which means some plants are male while others are female. Although both male and female asparagus plants can produce flowers, only the female plant produces fruit, which are small red berries that you’ll see clinging to asparagus ferns in the summer. Potentially you’ll harvest up to three times as many asparagus spears from male plants compared to females, an advantage that becomes especially apparent after the second or third year the plants are in your garden.

Choosing Crowns

In addition to our homegrown seedlings, we ordered 25 one-year-old, healthy, dormant plants, called crowns, available from reputable growers.  The 25 Jersey Giant plants we grew from seed is a cultivars that produces only male plants. Since these all male cultivars were developed by Rutgers University in New Jersey,  “Jersey” is usually part of the variety’s name.

These hybrids also tend to be more tolerant of warmer regions than older varieties, which usually grow in U.S. Department hardiness zones 4 through 8. For example, the cultivar “Jersey Giant” grows in USDA zones 3 through 10, while “Jersey Supreme” grows in USDA zones 2 through 9. The cultivar “Jersey Knight” is a vigorous cultivar that’s a good choice for humid areas, because it’s resistant to fungal disorders. It also does well in heavy, clay soils and grows in USDA zones 4 through 8.

Other Benefits

Male asparagus plants also tend to start producing spears earlier in spring than female plants, another benefit of an all-male plot.  Asparagus plants are perennials that usually live about 20 years, but male plants tend to live longer that female plants, probably because they expend less energy and use less stored nutrients during their life span.

Because male plants don’t produce fruits, an all-male plot won’t become filled with “volunteer” seedlings from dropped fruits. These seedlings tend to be inferior to carefully bred cultivars and also compete with adult plants for nutrients.

Creating a Bed

My granddaughter and I used a cinder block edging to enclose our asparagus bed which over the years has been a wonderful container planter garden surrounding the asparagus bed.  Over the years I’ve planted mint, tarragon, basil, peppers, roma tomatoes, Aunt Molly’s ground cherries, petunias, nasturtiums, four o’clocks, iris, lavender, violas and other small plant varieties in the two wells created by the cinder block when turned on its side and filled with soil.  The cinder blocks keep the other plants from invading the asparagus bed and create a living moat to complement the asparagus ferns after the spring harvest.

DIG YOUR BED

We dug down into the bed about 8 inches and covered the area with a mat of newspapers before planting the crowns.  The newspapers create a weed barrier to discourage invasion of noxious weeds and will decompose over time. 

Asparagus likes to be well fed so add compost or your chosen fertilizer to the prepared bed and work it into the trench-like rows where you will be placing and planting your crowns. 

Place the crowns 6 to 8 inches deep.  The actual “crown” – the knotty mass where all the roots join together – is planted face up. This is where the asparagus spears will emerge from, pushing their way up through the ground for harvest.  To plant the crowns, spread the roots of the crowns out on the bottom of the trench. Space plants about 12 to 15 inches apart, so they will have room to grow. Then fill the trenches with the soil dug out of the new bed.

The asparagus seedlings were easier to plant as we just transplanted them in their grow pots into the bed.  Over the years mulch, compost, fertilizer, leaves, and straw will add to the depth of the asparagus bed and be contained by the cinder blocks.

Water

The most necessary step for nearly all gardening projects: watering!  When first planting your asparagus crowns, give them a good, deep watering immediately after planting, and water more sporadically throughout the first season as needed (especially during dry periods and in hot, arid regions). Keep the water up to your bed during the growing season and pick daily as asparagus becomes fibrous if left to grow bigger.

Harvest

Stalks look good? Then it’s time to pick them – an easy task.  I use a sharp kitchen knife and cut the spear at ground level.  The best time to pick asparagus is during the morning and first half of the day.  On warmer days, you’ll see stalks getting taller and taller by the hour – so you’ll want to get them while they’re the optimum length, with bud tips still closed!

The next day and throughout the rest of the season (ideally spring until mid-June, or summer solstice at the latest), keep an eye on your bed every morning for stalks. 

I store the asparagus like I would flowers.  After cutting I put them in a vase, glass or pitcher with a little water in the bottom for the asparagus to slurp and put them in the refrigerator until I cook them.

Mulch

After watering, it’s a wise choice to mulch over your patch or row with a thick layer of organic matter – straw works best here. This adds a little extra nutrition, protection through cold weather, moisture retention, and reduction of weeds for less competition (and bigger spears).  I mulch with lawn clippings when I mow.  Keep watering your bed during the growing season and pick daily as it becomes fibrous if left to grow bigger.

Soil Amending

When fronds have not gotten too tall or crowded yet in their site, side dressing plants with compost or natural fertilizer will ensure that your plants get the adequate energy they’ll need to produce more delicious stalks next year – maybe even bigger ones!

Winter is Coming

When the ferns start to die off and turn yellow in autumn, cut them back to just above ground level. Cutting back green foliage can damage and shock the plant, rendering it less productive. Cover the plants with a good layer of compost for the winter.  I used vermipost (worm poo) to feed my asparagus bed,  The autumn leaves make a great mulch for the asparagus’ winter quilt,   

The asparagus wasn’t ready to eat the year that we planted it, but the next year we had several asparagus dishes. Ten years later we are enjoying an abundance of asparagus.  For our taste we have a sufficient supply for the year.  It is easy to freeze. Just wash, cut into 2-3 inch pieces, fill a sandwich bag, and put in the freezer.

My husband’s family homesteaded in eastern Colorado.  No one has lived on the homestead since the 1960’s, but we still find asparagus ferns from Grandma’s kitchen garden when we visit the farm.  I look forward to asparagus harvests for years to come.

This book has come just in time for me. As a long time gardener, I have an established rhubarb patch along with an asparagus bed. Come spring I’m swamped with these vegetables. This book has some interesting recipes for both of these veggies and I’ll be trying them very soon.

Pests and Diseases

While a hardy, hassle-free perennial, asparagus does suffer from some pests and diseases. While some of these only cause minor damage and not too much stress, it’s important all the same to check up on any potential issues from time to time.

A decimated asparagus patch will take a lot more time, work, and patience to restore to its former glory (sometimes even requiring fresh crown plantings) compared to the efforts required to ensure good pest management!

Pests

Asparagus Beetle

These are usually orange or orange-red and black, sometimes spotted, and they consume asparagus tips and ferns while laying eggs as well.

They can be removed with sprays (preferably organic), or introduction of a high population of natural predators (like some wasp species and lady beetles).

Asparagus Miner

A small black fly that damages stems especially, giving them red, unappetizing markings.

Removal and suppression are helped by early removal of foliage in winter – as well as burning to reduce any carry-over larval population into next spring. Sprays (preferably organic) are available as well.

Japanese Beetle

Iridescent-green or coppery-brown, these scarab-like beetles destroy above-ground foliage.

These can be kept away from your crops with preferably organic sprays, pheromone traps, or the introduction of natural predators (for example by attracting birds, or letting chickens run through the mature patch).

DISEASES

Fusarium Rot

A fungus that afflicts root, crowns, and lower stems, it creates unattractive, damaging patches of red on stalks, yellows above-ground foliage, and reduces yields.

As this happens to stressed plants, preventive measures are the only key to avoiding the problem: ensuring adequate watering, reducing pests, avoiding crown damage, and avoiding close rotation with previous crowns are all necessary practices.

Purple Spot

Purple spots on stalks and brown damage to ferns are the result of another fungal culprit.

Preferably organic sprays may help with spread. To prevent it, remove died-back foliage as early as possible, especially through burning.

Rust

This effects the foliage only and appears as a change of color to yellow and brown, leading to foliage loss.

Burning and early removal of foliage is a great preventative, as well as ensuring that crowns are planted with ample space for maximum airflow, to reduce the spread of disease after removal of infected plants.

Fusarium Wilt

Fusarium wilt is a common vascular wilt fungal disease.  Fusarium wilt affects many plant types, but tomato gardeners know this deadly, soil-borne disease especially well. Also known as stem rot, it moves into plants through their roots. From there, it clogs the plant’s passageways, blocking the flow of water, nutrients and vital juices until a plant wilts and eventually dies. 

Its first signs are yellowing and wilting on one side of the plant – a leaf, single shoot, branch, or several branches. Yellowing and wilting move up the plant as the fungus spreads. Interior of main stem (when split) shows discolored streaks from plugged water-conducting tissue.  Over time, many plants succumb and die, while others just perform poorly and produce few flowers or fruit.

Because of the contagious and tenacious nature of the fungus, control of fusarium should start with a few evasive procedures. Preventing the fungal wilt is preferable to most fusarium wilt treatments. 

Once fusarium wilt infects a plant, there is no effective treatment. Remove and dispose of affected plants immediately; don’t compost this garden refuse. Whenever possible, remove and replace fusarium-infected garden soil.  If fusarium wilt hits your garden, don’t plant the same or related plant types in that area for at least four years.  Depending on your climate, it may be possible to control fusarium wilt by “solarizing” your soil. This involves covering it with plastic so it reaches very high temperatures over a long period.

Happy, healthy gardening and gardens to you.