Asparagus, with its delicate spears and ferny foliage, is a garden gem that offers unparalleled flavor and beauty. For years, even as an experienced gardener, I hesitated to dedicate a permanent garden space to this perennial crop. However, discovering the joy of harvesting fresh, homegrown asparagus was a revelation. The taste and sweetness of asparagus straight from the garden far surpass anything store-bought, and the plants themselves, especially the female varieties with their ornamental red berries, add a unique charm to any garden. Whether you prefer roasting, steaming, sautéing, or blanching, asparagus is a versatile vegetable that becomes even more delightful with simple additions like garlic, lemon, or butter. If you’re considering growing asparagus in your own garden, this guide provides everything you need to know for a successful and rewarding experience.
You can also download my comprehensive How To Grow Asparagus? guide sheet for quick reference and easy access to this information.
While the red berries on female asparagus plants can be visually appealing, they actually divert energy from spear production. To maximize your asparagus yield, consider planting all-male varieties, which are specifically bred for higher productivity and spear quantity.
One of the most remarkable aspects of asparagus is its longevity. An asparagus patch can flourish and produce delicious spears for up to 20 years or more after initial planting. This makes it a truly worthwhile and long-term investment for any gardener.
Asparagus can be started from seed, but for most home gardeners, the quickest and most efficient method is to begin with crowns. Asparagus crowns are essentially one-year-old roots with developed buds. They are typically sold in packs of 25, and a standard pack of 25 crowns can yield approximately 20 pounds of asparagus spears annually once the plants are fully established.
Female asparagus plants produce visually appealing red berries, but these berries detract from spear production, making male plants a more productive choice for edible harvests.
Starting Asparagus from Seed: A Detailed Guide
While growing asparagus from crowns is generally faster, starting from seed offers a cost-effective alternative and can be quite rewarding. If you choose the seed route, ensure you source pathogen-free seeds from a reputable supplier. Asparagus seeds can remain viable for up to three years when stored properly in cool, dry conditions. However, for the highest germination rates, it’s best to use seeds within the first year of purchase.
Begin sowing asparagus seeds indoors approximately 12 to 14 weeks before your region’s last expected spring frost. To enhance germination, soak the seeds in water for a few hours prior to planting. In a clean seed-starting mix, sow the seeds at a depth of one-half to three-quarters of an inch. Maintaining a consistent soil temperature between 60° and 85° Fahrenheit (15° to 29° Celsius) is crucial for optimal germination, which typically occurs within 8 to 12 days.
Once seedlings emerge, place them immediately under grow lights. Insufficient light will cause them to become leggy and weak as they stretch in search of sunlight. About ten days before you intend to transplant your asparagus seedlings outdoors, begin the process of hardening them off. This acclimates them to outdoor conditions gradually. Start by placing them in a sunny spot for just one hour on the first day. Increase the sun exposure by an hour each day. By the end of the hardening-off period, usually around a week to ten days, the seedlings should be robust enough for transplanting into their permanent garden location in full sun.
Growing asparagus from crowns allows for harvesting spears a year earlier than starting from seed, but seed starting is a viable and economical method.
Optimal Location, Timing, and Planting Techniques for Asparagus
Choosing the right location for your asparagus is critical because it’s a perennial plant that can produce for two decades or more. Select a site that receives full sun (at least 6-8 hours of direct sunlight daily) to ensure vigorous growth. Asparagus foliage grows tall and fern-like, so position them where they won’t cast excessive shade on other sun-loving plants. The north side of your garden or a dedicated area where they can remain undisturbed for years is an ideal choice.
Asparagus thrives in soil with a neutral pH, ideally between 6.5 and 7.5. This pH range ensures the plants can efficiently absorb nutrients from the soil. Conduct a soil test through your local cooperative extension service to determine your soil’s pH level and receive recommendations for adjustments if necessary. A soil test will also identify any micronutrient deficiencies that should be addressed before planting.
Wait until the soil temperature consistently reaches at least 50°F (10°C) before transplanting seedlings or planting crowns outdoors. Using an inexpensive soil thermometer can provide an accurate reading of the soil temperature.
Plant asparagus crowns in early spring, except in very warm climates, where fall or winter planting is preferable.
For planting crowns, dig furrows that are 5 to 8 inches deep. Place the crowns bud-side up in the furrow, carefully spreading out the roots. In heavy clay soils, shallower planting is safer. Deeper planting is recommended in colder regions. Space crowns 8 to 14 inches apart within the row and maintain 3 to 6 feet between rows.
Initially, do not completely backfill the furrows. Cover the crowns with just 2 to 3 inches of soil at planting time. As the asparagus spears emerge and lengthen, gradually add more soil to fill the furrow completely. This trench planting method helps to blanch the lower portion of the spears and encourages strong root development.
Plant asparagus in a location with full sun and well-amended soil enriched with compost to promote optimal growth and spear production.
Exploring Asparagus Varieties for Your Garden
Garden asparagus all belongs to the same species, Asparagus officinalis. However, numerous varieties have been developed to offer different characteristics, such as tolerance to varying climates (cool or warm) and resistance to specific diseases. Asparagus spears can be green, purple, or green with purple tips, offering visual diversity in your harvest.
The green color in most asparagus comes from chlorophyll, while anthocyanin, a pigment, is responsible for the purple hues seen in the tips or entire spears of certain varieties. “White asparagus,” a delicacy popular in Asian and European cuisines, is actually green asparagus grown under mulch or soil. Depriving the spears of sunlight prevents chlorophyll development, resulting in tender, white spears.
Here are some notable asparagus varieties to consider:
- Erasmus: The first all-male purple asparagus variety. Known for its sweeter flavor and tender texture. Matures mid-early and thrives in zones 3-10.
- Guelph Millennium: An all-male variety developed at the University of Guelph in Ontario. Highly cold-tolerant and productive, producing tasty green spears. An RHS Award of Garden Merit recipient, well-suited for Canada and the northern United States.
- Jersey Giant: Part of the Jersey series of all-male varieties. Features medium to large green spears with attractive purplish bracts. Cold-tolerant and rust-resistant.
- Jersey Knight: Produces large, uniform green spears. Adapts well to most climates and exhibits high rust resistance. More tolerant to fusarium than many other varieties.
- Jersey Supreme: A high-yielding variety with slender green spears. Suitable for both cool and warm regions, and also rust-resistant.
- Mary Washington Improved: An open-pollinated green variety that offers improved spear production and tighter tips compared to its predecessor, while maintaining excellent flavor. Less heat-tolerant, best harvested before temperatures exceed 70°F (21°C).
- Pacific Purple: A British variety known for its flavorful and high-yielding nature. Produces extra-thick, deep-purple spears. If grown from seed, expect the first harvest after approximately 750 days. Rated for zones 3-9.
- Purple Passion: Features large-diameter purple spears that are sweeter and more tender than green varieties. Emerges later in the season, which can be advantageous in avoiding early frost damage. The purple color fades upon cooking.
- Spartacus: An all-male hybrid variety with green spears and purple-tinged tips. More productive than Jersey varieties, producing consistently long spears (over 9 inches). Well-adapted to both cold winters and warm summers.
Chlorophyll gives most asparagus its green color, while anthocyanin contributes to the purple hues found in certain varieties and spear tips. (Photo: Amy Prentice)
Watering Asparagus for Optimal Growth
Consistent and even watering is crucial for asparagus, particularly during the initial establishment phase and throughout the growing season. Avoid overhead watering as wet foliage can encourage fungal diseases. Water directly at ground level. Applying a layer of mulch around your asparagus plants helps to conserve soil moisture between waterings and acts as a barrier against soilborne pathogens.
Asparagus is exceptionally well-suited for drip irrigation systems. Drip lines can remain in place for many years, providing consistent moisture directly to the roots. This method ensures the soil stays consistently moist, which is vital for healthy spear development during the growing season.
Drip irrigation is a highly effective method for watering asparagus, providing consistent moisture and convenience.
Fertilizing Asparagus for Long-Term Productivity
Asparagus benefits from a steady supply of nutrients. Amend the soil regularly with well-rotted manure, compost, fish emulsion, or a balanced organic fertilizer. Applying organic mulch around the plants also contributes nutrients to the soil as it decomposes.
As perennial plants, asparagus will grow and produce for many years. Ensuring they have access to essential resources throughout their active growing periods is key to maintaining productive plants season after season. Fertilize in early spring before spear emergence and again after the harvest season concludes to replenish nutrients and support fern growth.
Managing Asparagus Pests and Diseases Organically
Asparagus can encounter certain pests and diseases, but these can be effectively managed by selecting resistant varieties and employing organic control methods. Using floating row covers over young plants can prevent many insect pests from accessing them to lay eggs. Row covers act as a physical barrier and, while they need to be removed as plants grow taller, they provide significant early protection. Maintaining weed-free beds, avoiding overhead watering, and using sanitized tools during harvest are also crucial steps in minimizing pest and disease problems.
Here are some common asparagus pests and diseases and organic management strategies:
- Asparagus Aphids: These tiny insects cause deformed and stunted growth by feeding on spear tips. Aphids are sap-sucking insects that can also transmit plant diseases. Their feeding excretes honeydew, which attracts ants and other pests. Control aphids by dislodging them with a strong stream of water or applying insecticidal soap.
- Asparagus Beetles: Both common and spotted asparagus beetles can be problematic. The common asparagus beetle is more damaging as it lays eggs and feeds directly on spears, causing deformation and damage. Spotted asparagus beetles also feed on spears but typically lay eggs on the fern foliage. Handpicking beetles, using row covers, and applying neem oil can help manage infestations.
- Cutworms: These caterpillars cause bent or crooked stems by feeding on roots and stems, often at the soil line. Cutworm larvae overwinter in the soil as eggs or larvae, so row covers are not effective against them. Consistent weeding and using cardboard collars around young plants can reduce cutworm damage.
- Japanese Beetles: Adult Japanese beetles can cause significant foliage damage, reducing photosynthesis and plant vigor, which in turn lowers productivity. Adults are about 3/8 inch long with metallic copper-colored wing covers and green iridescent bodies. Larvae are white grubs found in the soil. Control grubs with Bacillus thuringiensis galleriae (Btg), milky spore, and parasitic nematodes. Adult beetles can be handpicked or controlled with Btg. Refer to specific guides for detailed Japanese beetle management strategies.
- Fusarium: This soilborne or seedborne fungus causes various symptoms, including root rot, crown rot, and wilting. Ensure good soil drainage, practice crop rotation, and use disease-free seeds and crowns to prevent fusarium issues.
- Purple Spot: A fungal disease that causes sunken purple lesions on stalks and tan or brown lesions on foliage. Promote good air circulation, avoid overhead watering, and apply copper fungicides if necessary.
- Rust: A fungal disease characterized by orange spore masses on plant stalks. Choose rust-resistant varieties, ensure good air circulation, and use sulfur-based fungicides if needed.
Harvesting Asparagus at the Peak of Freshness
Your first asparagus harvest can begin in the second spring after planting crowns. If you started from seed, expect to wait an additional year before harvesting.
During the initial harvest season, harvest lightly, taking only two or three spears per plant to allow the plants to establish. In subsequent years, harvest pencil-thick spears when they reach about 6 to 8 inches tall. Continue harvesting as long as the spears are more than three-eighths of an inch in diameter. Signal the end of the harvest season when most new spears remain thin and the bud tips start to open and fern out. Allowing the remaining ferns to grow fully will replenish the plant’s energy reserves for the next season.
Harvest spears by either cutting or snapping them off near the soil level. However, snapping spears is often preferable. Grasp each spear between your thumb and forefinger and snap it near the base. The portion that breaks off in your hand is the tender, most desirable part to eat. The tougher, woody base of the spear is best left in the garden rather than discarded in the kitchen.
Asparagus is best enjoyed incredibly fresh, ideally on the same day as harvest or as soon as possible thereafter.
At the end of each growing season, after the ferns have turned brown and stiff (typically by fall), cut back the ferny growth to ground level. You can leave the cut ferns in place as a natural mulch. This is also a good time to test your soil pH and incorporate compost or other soil amendments. Finally, cover the bare soil with a layer of straw or shredded leaf mulch for winter protection and soil enrichment.
Harvest asparagus spears by snapping them off at the base to ensure you are only taking the most tender and edible portion.
Growing asparagus is a rewarding endeavor that provides fresh, flavorful harvests for years to come. With proper planning, planting, and care, you can enjoy the delightful taste of homegrown asparagus straight from your garden.
What are your successful asparagus growing tips? Share them in the comments below!
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Links & Resources
Note: Some product links below are affiliate links. See full disclosure at the end of the article.
Episode 094: How to Start and Care for Seedlings Indoors: My Steps for Success
Episode 99: Understanding Crop Rotation: The Basics and Beyond, with Jack Algiere
Episode 195: Identifying and Controlling Garden Pests Organically
Episode 204: Hardening Off and Setting Plants Up for Success in Spring
joegardener blog: Powdery Mildew Prevention & Control
joegardener blog: How Do I Grow Artichokes?
joegardener blog: How Do I Grow Beets?
joegardener blog: How Do I Grow Broccoli?
joegardener blog: How Do I Grow Brussels Sprouts?
joegardener blog: How Do I Grow Cabbage?
joegardener blog: How Do I Grow Cauliflower?
joegardener blog: How Do I Grow Herbs?
joegardener blog: How Do I Grow Melons?
joegardener blog: How Do I Grow Onions?
joegardener blog: How Do I Grow Peas?
joegardener blog: How Do I Grow Peppers?
joegardener blog: How Do I Grow Spinach?
joegardener blog: How Do I Grow Strawberries?
joegardener blog: How Do I Grow Summer Squash?
joegardener blog: How Do I Grow Swiss Chard?
joegardener blog: How Do I Grow Tomatoes?
joegardener blog: How Do I Grow Winter Squash?
joegardener blog: Japanese Beetle Prevention & Control
How Do I Grow Asparagus? one-sheet
joegardener Online Gardening Academy™: Popular courses on gardening fundamentals; managing pests, diseases & weeds; seed starting and more.
joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.
joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out.
joegardener Online Gardening Academy Growing Epic Tomatoes: Learn how to grow epic tomatoes with Joe Lamp’l and Craig LeHoullier.
joegardener Online Gardening Academy Master Pests, Diseases & Weeds: Learn the proactive steps to take to manage pests, diseases and weeds for a more successful garden with a lot less frustration. Just $47 for lifetime access!
joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.
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Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Rain Bird, Corona Tools, Milorganite, Soil3, Greenhouse Megastore, Territorial Seed Company, and TerraThrive. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.
About Joe Lamp’l
Joe Lamp’l is the creator and “joe” behind joe gardener®. His lifelong passion and devotion to horticulture has established him as a trusted and recognized figure in organic gardening and sustainable practices. This expertise is evident in his role as host and creator of the Emmy Award-winning PBS series, Growing a Greener World®, currently in its tenth season. Beyond his television work, Joe is actively involved in his raised bed vegetable garden and organic farm north of Atlanta, GA, where he gardens, plants, and enjoys time with his family.
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