Asparagus is a plant that has been places, with a history that dates back to the dawn of man. Primitive hunter gatherers seeking something fresh after a long winter were likely the first to chance across asparagus spears. Now, anyone from the health conscience to people looking for a quick, delicious meal can enjoy asparagus straight from the supermarket.
But why settle for store-bought spears when you can grow highly ornamental and nutritious plants in your own yard? In this article, you’ll find information about how to:
- Select the appropriate asparagus varietiesDetermine an appropriate location for your asparagus bed
- Prepare a bed for planting
- Care for asparagus until they mature
- Control pests and diseases
- Harvest and store your asparagus
- Find tasty asparagus recipesLearn about a few of the more interesting aspects of asparagus and its history
Asparagus (Asparagus officinalis) is actually an offshoot of the lily family and related to several of our best garden vegetables (onions, garlic and chives) and favorite ornamentals (Easter lily, Asiatic lily, belladonna and amaryllis). While the focus of this text is mainly on the varieties of asparagus you can actually eat, we’ve also included a few ornamental varieties for those who simply want an attractive container plant.
Preparing a Bed for Asparagus
Asparagus thrives in well-drained soils that get full sun for at least six hours per day. It’s important to note that asparagus can grow in a variety of soils — from sandy loam to clay. But, the area you select must be well-drained and prepared correctly (see bed preparation below).
Planting asparagus in poorly drained soil — especially poorly drained clay — would be the equivalent of flushing several twenty-dollar bills or more (depending on the size of your crop) down the commode. (Unfortunately, I have personal experience in this area that I’d rather not share.) Imagine spending hundreds of dollars on a properly laid out bed of good quality asparagus plants and the appropriate compost, amendments, mulch, etc. only to lose your asparagus – along with hours of hard work – to the pitfalls of poorly drained soil.
You must check drainage — both internal soil drainage and surface runoff — to make sure your beds don’t get wet feet. Surface drainage is rather straight forward. Simply don’t place the beds in a sinking or low-lying area, or where excess water runoff occurs during a rain. If you can’t plant anywhere else, plant in raised or mounded beds. Then, create trenches to divert the excess water away from your plants.
Internal drainage is a little trickier to deal with and test. For this test, make sure the area you’re testing is moist. If it isn’t, water the area as you would water a fully planted garden bed (or until the soil is moist to about one-foot deep). The next day, dig a hole (or several) about one-foot deep in the areas where your asparagus is to be planted and fill each hole with water. Check the next day to see if the water in the holes has drained away. If the water is gone, especially in clay soil, your drainage should be just fine for asparagus beds. If water is still standing in the hole, you will more than likely need to create a raised bed.
You will need to use your own judgment to determine whether or not the water test was accurate. For example, if your region is experiencing extreme drought or unusual weather conditions, your soil may have drained faster (or not drained as fast) as it would have in normal conditions.
Important asparagus culture info — A unique concern with asparagus is that it accumulates the heavy metal arsenic. Asparagus has an affinity for arsenic and adds it to its growing tissue, usually in such small quantities that it is actually good for you. Just enough arsenic is good for the heart, but too much is dangerous.
You only need be concerned if the area you’re considering for planting has come into contact with CCA (chromated copper arsenate) treated lumber. A few wood shavings or scrap pieces of CCA-treated lumber left near the asparagus bed site should not be a problem. However, large amounts (a shovel full or two) of CCA sawdust or scrap pieces spread or buried near your asparagus beds could make your asparagus poisonous.
Another, far lesser problem is arsenic accumulation in old cotton fields. The cotton crops of old were sprayed with calcium arsenate, and the residue is still hanging around. This should not be a problem unless there was a significant concentration where you placed your asparagus plants.
Bed preparation, planting and cultural requirements
Remember when your parents and teachers told you time and again that patience is a virtue? Well, you’ll definitely need to heed that advice if you plan to be an asparagus grower! It can take up to three years to produce a decent harvest of asparagus spears, even when you select plants older than 1 year, which is not recommended. Adequate bed preparation will go a long way toward ensuring a timely and successful harvest. Likewise, cutting corners will almost certainly lead to profound regret.
Planting asparagus in well-drained, raised beds in trenches no deeper than six inches works best. The beds can be prepared for the asparagus several months before you set out the plants. You will have to add more fertilizer at planting time when you plant asparagus in beds that have been sitting around for awhile.
To prepare your beds for planting, a test of your soil’s fertility and pH is essential. It will help you determine which additives, and how much of each, your bed requires. One of the more interesting aspects of asparagus culture is its fondness for soil that is near neutral or alkaline (high pH), not acidic. Soils with an acid pH of less than 6.5 can stunt — or even kill — asparagus. If your soil is too acidic, you’ll need to apply the appropriate amount of lime as indicated by your soil test. If your soil is alkaline, you may still need to apply an appropriate amount of sulfur, Epsom salts or products high in micronutrients like seaweed and Garrett juice.
Buying and applying amendments should be based on what your soil test results recommend. Soft or colloidal phosphate is good for just about any soil type and can be spread right onto the crowns during planting to give them a boost. Don’t forget to apply all of the needed nutrients, not just a few. Asparagus tends to like phosphate, but just because it likes more phosphorous doesn’t mean it can live without the other nutrients. Always apply some nitrogen, potassium, and other micronutrients, (see below for good fertilizer choices) preferably organic.
The area in which the amendments should be applied in the asparagus bed should be about 4- 5 feet wide and at least 5 feet in length for two plants, adding about 1 1/2 feet of bed length for every plant added. There should be at least 1 1/2 feet of bed after the last plant at each end of the asparagus bed.
It’s important to note that you should not remove your native soil and fill with other material. This can cause a sink that will fill with water and cause root rot. Also, you shouldn’t add a foreign type of soil to your bed or furrows (e.g., sand to clay or clay to sand). This can pack the soil or create a sink for water to collect. Use only native or a similar type of soil to raise your bed.
If the soil is very acid (below 5.5), an application of lime tilled into the area around the asparagus bed would help prevent the growing roots from reaching acid soil. Adding 3 to 6 inches of well decomposed compost, manure or other similar organic matter is the first thing you should apply to any asparagus bed. Commercial producers don’t always do this but it is definitely beneficial.
It is usually best to make the compost yourself, but your local garden center will sell it by the bag. You may want to research the best ways to produce compost before buying a system – otherwise, you may end up with supplies that are ill-suited to your needs.
You’ll want to avoid manure from auction barns or other places where animals could have eaten bermuda hay sprayed with Graizon, Picloran, or 2-4-D. Believe it or not, potent herbicides can pass through an animals digestive track and last for years in the soil! More important, they can be fatal to your asparagus. Dairy manure is often a safe choice, just be sure.
Do not till organic matter down deeper than eight inches, especially in clay soil. This can cause bad decomposition and produce things dangerous to your plants, not to mention its also a lot of back-breaking labor that you don’t need.
Cornmeal, especially horticultural grade cornmeal, is a good amendment for asparagus because there is lots of evidence that it kills Fusarium, the disease that causes rot in asparagus. Apply it at the rate of 20 lbs per 1,000 square foot of bed area.
Adding a product that contains Mycorrhizal fungus such as Gardenville Mycorrhizal fungi, can help your asparagus absorb phosphate and protect it from diseases.
Once you’ve assembled and applied the appropriate additives, they should be tilled around 6-8 inches deep into the native soil or raised bed.
Asparagus should be planted when the soil temperature is at or above 50 degrees. Planting in colder, wet soils could cause root rot. Generally, those in zones 7 and southward should plant in January and February, zones 5 and 6 should plant in March and April, while zone 4 dwellers should plant April and May. Check your gardening reference books or ask local nurserymen or agriculture office/extension agents to find the best time to plant in your area. (Asp pic 5-” Asparagus plants fresh out of the bag”)
Make sure to soak the asparagus roots, whether just the crowns or transplants with foliage, in a liquid seaweed solution or other biostimulant rich in micronutrients like Great big plants or Garrett juice for about thirty minutes prior to planting. This will help prevent transplant shock and keep them moist until you have finished burying and mulching the bed.
Ideally, asparagus roots should be planted no more than 6 inches deep and 1-1/2 feet apart in the middle of bed rows that are 4-5 feet wide. Remember, if your soil drains poorly, you’ll need to plant your asparagus in raised beds with 6 to 8 inches composed of native soil and the appropriate amendments. If planting in raised beds, you’ll want to include the soil in the raised bed when measuring how deep to plant. In other words, plant your roots 6-8 inches deep from the surface of the raised beds. Going deeper — especially in clay — could be deadly.
If planting asparagus from transplants that already have foliage, plant them at the same depth as you would bare crowns. As they grow, cover their stems until the soil level is even with the rest of the beds. Be careful that you don’t drown the plants by letting the trench fill with water.
Place the asparagus in the trench or hole. Spread the roots gently, taking care not to break any stalks that might be trying to grow. There is no need to worry about which end of the asparagus is pointing up or down. Asparagus plants will grow and eventually right themselves if planted upside down.
Spread about a fourth of a cup of the appropriate phosphate fertilizer(see fertilizing), or a handful of soft phosphate around and on the asparagus crowns before they are covered with soil.
Cover the asparagus with soil up to the top of the bed. You do not need to slowly cover the plants as they emerge. Just cover them up all the way.
Apply a layer of mulch. It is important to keep your plants adequately mulched. Make sure you maintain around three to six inches of mulch over the entire bed, except when you have just planted your bed. Keep heavy mulch away from where the first shoots will be coming up or slugs, crickets or other pests could get the first spears. After they have emerged and begin to leaf out you can mulch almost (three inches away) up to the stems.
If you can find it, the best mulch is your local shredded tree trimmings, partially finished compost, decomposed leaves or decomposed hay.
You’ll want to stay away from Bermuda grass hay for mulch, unless it contains a mixture of other plants (clover, rye, or other forbs) and you know with certainty that it has not been sprayed with herbicide. Bermuda grass is often sprayed with very powerful, long lasting herbicides that can kill plants for years!
Water your plants in well with about one to two inches of water and then spray any liquid amendments over the planting area.
Protect your planting from pests and critters if needed. A large dog can really mess up a new asparagus bed. Fencing or thorny clippings usually work well for this. Whew, that was a long section, but if you followed it the asparagus should be set on the right track to a good harvest in two to three years.
Asparagus plants can be classified as male, female or male hybrid plants. Male plants generally produce more spears than female plants — sometimes three times more spears than female plants — and they don’t produce seed that can spread throughout the garden. There are also rust- and fusarium-resistant varieties, rust and fusarium rot being two diseases common to asparagus.
Some varieties of asparagus have been used reliably for decades. In fact, certain varieties have been planted and harvested for nearly a century. But, many of the new varieties are equally delicious, more productive and even more disease-resistant. While the varieties below are perhaps the easiest to find, your local university extension, nursery or agricultural extension officer will be able to tell you what grows best in your area.
Basic wild asparagus – This can be started from seed and planted into a bed after one year of nursing it in a growing area for transplanting. While this variety may be tasty, it has little, if any, disease resistance. Additionally, success with wild asparagus seedlings is often mixed.
Mary and Martha Washington – These very old stand-by dioecious varieties (female or male) are rust-resistant. While these are out-produced by the modern male hybrids varieties, they are still tasty and reliable plants. They can, however, seed out to other areas in the garden.
Jersey Giant, Jersey Prince, Jersey Knight – These male hybrids are rust- and fusarium-resistant. Because they don’t seed out, you won’t have to worry about seedling plants sprouting throughout your yard and potentially spreading disease. These do very well in the north, but should also do well in southern climates.
UC-157 – Developed by UC Davis, this variety is recommended for southern climates. It has been bred for rust- and fusarium-resistance. Additionally, this variety is easy to start from seeds.
It’s usually best to get asparagus crowns from a local supplier, rather than from a mail order catalog. This gives you the ability to check the roots to make sure they are healthy before you purchase them. Local suppliers also tend to stock varieties appropriate for your area. (I recently bought Mary Washington roots from our local Wal-Mart.) If you are not able to purchase roots locally, try to find a respectable asparagus supplier. Also, avoid buying large, mature plants (two years or older) with the hope that you will get a jump on asparagus spear production. Older plants may need a couple of years to recover from transplanting.
Certified disease-free seed is another way to start asparagus, but it can take up to an extra year to get transplantable crowns. If starting from seeds, set them out in seed trays and let them grow roots to the bottom of the trays. Then, bump them up to larger containers to grow to about 8 inches tall. Once they are large enough, transplant them to the garden site.
Alternately, they can be seeded directly into the prepared planting bed. After a few months, they should reach a size suitable for transplanting into a nursery row or directly into beds. Check your climate zone for the appropriate seeding and transplanting times.
In case you ever wondered, the asparagus “ferns” you often see are, in fact, really asparagus, but they are not edible (as far as I know). A couple of ornamental favorites include:
Asparagus Densiflorous – The basic asparagus fern. A good hanging basket and pot plant, it grows from spring until the first hard freeze. It can take some freezing weather, but it is not nearly as cold-hardy as the edible asparagus. Some people try to save favorite or special plants from year-to-year, but if you keep them in the house, they will drop needles everywhere.
To prevent this problem on a plant that must be indoors, give it good light and use a weak fertilizer like seaweed, terra cycle or Great Big Plants at regular or lower-than-normal rates. Also take care not to stress your plants from too much or too little watering. To avoid these problems, you may want to try passive systems such as self-watering pots or soil water crystals can help prevent this from happening.
Asparagus setaceus – This is a very unusual climbing asparagus (up to 10 feet) with attractive white flowers and black berries. It also has a few thorns, so be careful where you place this plant in the house. The only place it can grow permanently outdoors is in the Deep South (zone 9 and warmer).
Ongoing care of asparagus plants
Now, here’s where your patience will play an important role. Once your plants are in the ground, you can just sit back and enjoy taking care of them — for the next two to three years! Here are a few tips:
Fertilizing and watering
Water newly established plants deeply around once a week to two weeks. Always adjust for weather and the soil condition. Never just water on a schedule, the plants can be killed if watered when already wet. Fungal and bacterial diseases can overwhelm young asparagus plants if they are watered too frequently in moist or cloudy climates.
Once established, asparagus is relatively drought tolerant and only needs infrequent, deep watering through the summer. It does need more frequent watering in dry climates with low humidity. Water asparagus before the first hard freezes in your area if there has been little rain and the soil is not moist around the asparagus bed. Don’t drown them, just give them around an inch of water to prevent them from drying out over the winter.
Make sure the plants are mulched with three to six inches of mulch at all times of the year. See the bed preparation section for more information on mulch selection.
How to fertilize the asparagus after it’s in the beds largely depends on how well-established the plants are, the size and maturity of the plants and whether you are done harvesting spears for the year. Always reference the original soil test.
Nitrogen fertilizers should be applied more heavily to plants in their first two years of growth that are still being established and aren’t being harvested. You can also use fertilizers higher in nitrogen just after you’ve finished harvesting spears on older plants to promote top growth. However, too much nitrogen applied to established plants before a harvest can cause lots of weak, fast-growing spears to form on the plants. To avoid this problem, use organic or slow-release nitrogen fertilizer such as bone meal, cottonseed meal, liquid fish or meal, or hasta gro lawn.
In general, asparagus should be fertilized with more phosphorous, and not as much nitrogen, before and during the spear harvesting. Fertilizers such as bone meal, rock phosphate, Superphosphate (NOT triple superphosphate), HastaGro plant, Mega green, etc. should work for this purpose. Use Superphosphate in alkaline soil and rock or brown phosphate in acid soil. Soft (colloidal) phosphate can be used in any soil.
If your soil test calls for potassium, use sul-po-mag, potassium sulfate, granite or greensand. You can also use muriate of potash (potassium chloride) in small quantities.
Avoiding and controlling pests and diseases
Asparagus beetle – (Crioceris asparagi) This lousy pest produces larva who love to eat asparagus stems. You can control them with various natural sprays derived from plants, such as pyrethrum, spinosad, neem, or d-Limonene. You may also be able to control them with beneficial nematodes, applied early in the spring (when temperatures are above freezing) or in the fall. You can find beneficial nematodes at many mail order insectaries across the country.
Rusts (Puccinia asparagi) – This fungus attacks the stems first and then goes after the rest of the plant. It appears in the form of small rust-like flakes on the surface of the asparagus. Its flakes grow and finally burst, releasing a cloud of spores that will infect other asparagus. This can be deadly to your plants, but only if the infection is allowed to become severe. If your plant is attacked, spray or dust the infected stems lightly with sulfur, garlic or a fungicide (preferably organic) such as Greencure, which may work on rust. Then, burn, toss or hot-compost the stubble after it has died back in the winter.
Applying cornmeal at 20 lbs per 1,000 sq. ft. over the infected area may help prevent this disease from returning.
Asparagus grown in moist climates with frequent mists, rains or a wet spring season will be more prone to asparagus rust. Talk to your local gardening experts to see if you live in a rust-prone area and, if so, plant a rust-resistant variety. Mary and Martha Washington are both bred for their resistance to rust. While Martha Washington is more rust-resistant, Mary Washington is the better plant overall.
Fungal and bacterial rots (fusarium sp. and others) – These and other rots caused by poor drainage are the most serious long-term problem with homegrown asparagus, but the good news is that it is a disease you can prevent. In order to prevent these rots from taking hold of your asparagus, you need to plant them in well-drained soil that gets full sun, or in properly prepared raised beds. Always make sure the beds drain well and don’t “pond” in wet weather. If drainage is the problem, there are only two things you can do. Fix the drainage on site or move the beds to a more appropriate location and start over. If you already have a problem with fungus, try cornmeal (which both absorbs water and deters fungus). This can be applied at 20 pounds per 1,000 square feet.
If you’ve done everything right, you can expect to reap the benefit of full, firm, hardy spears during the springtime of your asparagus’ third year. These older plants should be able to give you 4-8 weeks of good spears over 1/2 inches in diameter and larger. For home harvesting, simply snap off the spear as close to the ground as you can.
Cutting asparagus spears with a knife is not that important, and it really doesn’t help too much with the yield size. Avoid cutting with a knife below soil level if you don’t know where the crown is located. Once the asparagus spears are 3/8 inches, stop harvesting, fertilize appropriately (see above) and let your plants start to grow their beautiful foliage for the next season’s crop.
You can harvest some spears the second year, but be careful not to harvest for too long (no more than 4 weeks). If the spears are smaller than 3/8 inches round, stop harvesting. The best time to harvest asparagus is when spears are 4 to 10 inches tall. If your spears are tough or the heads are not tight and have begun leafing out, they have grown too tall and old for harvesting. In some areas, you might have to harvest every day to prevent the spears from getting woody or fibrous.
If spears become fibrous and you are not near the end of your harvesting season, cut them off and let new spears grow in their place. You could also just leave these spears to develop and cut others that grow around them. The idea is that the developing spear may help feed other spears and increase the harvest. Allowing the foliage to grow may also cause future spears to get tough faster or just stop as many from coming up. You will have to try it out for yourself to see which idea works.
Inadequate spears can indicate underlying problems. Thin spears can be a sign of over-harvesting or lack of fertility. Tough spears can be a sign that your plants are not getting enough nutrition or water, or that the beds need to be renovated (more mulch, slow release/organic fertilizer, compost, etc.)
Asparagus can be frozen for extended periods, cut or whole. To store, blanch fresh asparagus for up to two minutes (depending on the spear size). Then, immediately place the spears in cold water until cool (a few minutes). Finally, drain your spears, wrap them tightly in plastic food wrap and place them in the freezer. They should keep for several months while you find the time to make something delicious with them.
For short-term storage solutions, some sources suggest wrapping thoroughly washed asparagus in air-tight plastic and placing a moist paper towel over their cut ends in the vegetable crisper. I have had luck with just the moist paper towel layers wrapped around the cut tips. The asparagus I have stored in this manner last up to two weeks.
If you thought asparagus was only served steamed or canned, you are in for a surprise! It can be pan fried, added to stew, used as a key element of frittatas and much more. Asparagus by itself does not take long to cook (5-10 minutes, depending on the spear thickness). Overcooking may cause mushiness. In general, when using asparagus, the bottom 1/2 inch of the stem should be removed because it tends to be tough and not easy to eat. When it comes to asparagus recipes, a couple of my personal favorites include:
Low-carb asparagus frittata
1/4 cup onions, chopped
1/2 teaspoon salt
7 asparagus spears, tough ends snapped off, and cut into 1-inch pieces
5 large eggs, lightly beaten
1 cup Monterey jack cheese or 1 cup cheddar cheese.
Heat olive oil in a 10 inch oven proof pan over medium high heat. Add onions and salt, and cook, stirring occasionally until softened, about 3 minutes. Add asparagus, reduce heat and cook, covered until it is barely tender, about 6 minutes. Pour in eggs and cook until almost set, but still slightly runny on top, about 3 minutes. Sprinkle cheese over eggs and put in oven to broil until cheese is melted and browned, about 3 minutes. Remove from oven and slide onto a serving plate; cut into wedges.
One bundle asparagus
1/4 cup olive oil
Parmesan cheese grated (add to taste)
Pre-heat oven to 350. Place just enough asparagus to cover the bottom of a coverable oven save dish and add the olive oil. Spread the parmesan cheese over the asparagus, cover, and place in oven for approximately 30 minutes depending on the oven and the desired tenderness.
Interesting, but strange facts about asparagus
Asparagus makes your urine smell weird. No, you aren’t crazy — after eating asparagus, many people can still smell it later! Natural compounds in asparagus break down in the body to form Methylmercaptans or Methanethiol — the jury is still out on the exact compound our bodies produce, which gives your urine this unique aroma.
Strangely, the smell is produced by the same class of chemicals responsible for the foul odor produced by skunks, and some people are unable to smell the chemical due to a genetic variation!
Asparagus is a mean, green, cleaning machine.
Asparagus has the unusual ability to absorb arsenic and some other heavy metals from the soil in large quantities. Several species of asparagus are currently being researched and tested for environmental cleanup. Asparagus can give you gout (if you eat a ton of it)! Compounds called purines in asparagus break down in the body to form uric acid, the compound that causes gout. Unfortunately, some people do get gout from asparagus, but typically only after consuming large amounts of asparagus — perhaps several pound a day!
What the heck does “asparagus” mean? The word comes from the ancient Greek or Persian word “asparag” which means sprout. It was given this name because it is one of the earliest — if not the earliest — harvestable fresh vegetable in many parts of the world. Socrates and the Spartans ate asparagus. The Greeks where probably the first to cultivate asparagus in large quantities. It was a favorite for improving health and vigor of people after the winter.
No sensitive, young eyes should read the following paragraph!
The Greeks saw the asparagus spear, like they saw so many other aspects of their world, as a phallus — any children reading this should ask their parents. Because the Greek culture was obsessed with the phallus, they believed almost anything similarly shaped was a symbolic representation of the phallus. Even the columns of many of their buildings where carved to look like them. Their fondness for the phallus naturally led them to develop a fondness for the asparagus spear.