How to Grow Asparagus in a Raised Bed
Because of its longevity, having a dedicated asparagus raised bed is a great plan. In this guide, we go over everything you need to know to start yours! You'll enjoy these perennial vegetables year after year.
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Asparagus is a long-lived perennial vegetable that grows in USDA zones 3 through 8. It requires rich, well-drained soil, consistent moisture, and minimal weed competition. What better place to grow asparagus plants than in a raised bed, where you can easily amend the soil with organic matter and control growing conditions from the start. Asparagus plants can live for up to 20 years, so planning the location of your asparagus raised bed carefully is essential.
One of the biggest benefits of planning an asparagus bed is the ability to manage the conditions asparagus prefers while keeping long-term maintenance simple and manageable. Asparagus can be grown from seed, but it is most commonly planted as crowns that are about two years old and have well-developed root systems.
With just a few simple steps, you can set yourself up for decades of productive gardening in an easy-to-reach raised bed. Growing asparagus in a raised bed also makes it easier to maintain soil quality and moisture levels over time. If you want to learn more about the benefits of growing asparagus in a raised bed, keep reading.
Small Modular Metal Raised Garden Bed Kit
Small Modular Metal Raised Garden Bed Kit – 15” Tall
Round Metal Raised Garden Bed Kit
Round Metal Raised Garden Bed Kit – 15” Tall
Why An Asparagus Raised Bed?
There are many reasons to grow asparagus in a raised bed garden.
Because you fill the raised bed yourself, you can use much higher-quality soil than you would for in-ground planting. It is easier to amend the soil throughout the entire bed from the start, giving you full control over how much compost you add and which soil amendments you use. Raised beds also provide excellent drainage, which helps protect the root system from rot and other moisture-related issues.
A raised bed is easier to manage on a daily basis because there are far fewer weeds, and those that do appear can be pulled by hand with ease. Taller raised beds also reduce the need to bend over. You can easily install drip irrigation or a soaker hose system, which cuts down on watering time and helps maintain consistent moisture levels.
Another advantage of a raised asparagus bed is the ability to fine-tune growing conditions specifically for asparagus. This includes your watering and fertilizing schedule, how and when you mulch, and the types of row covers you use throughout the season.
Raised beds warm up faster than in-ground soil, which gives asparagus an early start in spring. You can also use covers to speed up soil warming and protect plants from sudden temperature fluctuations, helping asparagus emerge sooner and grow more vigorously.
Beyond practicality, raised asparagus beds can add visual interest to your garden. Since asparagus is a perennial, it can serve as a featured planting. Position the bed where you can enjoy the airy, fern-like foliage in summer or use it as a natural conversation starter.
Finally, harvesting asparagus from a tall raised bed is far easier than harvesting from the ground. You can simply walk by and snap off spears as they reach harvest size, making the process quick and comfortable.
Asparagus Spacing In Raised Beds
Normally, you would plant asparagus crowns or seeds 18 inches apart in rows, which are then spaced several feet apart from each other. This protects the delicate root systems and allows the plants plenty of room to spread out, as well as space for you to walk along the rows and access your plants as you care for them.
In a raised bed, you do not have to space the rows so far apart. Because you can walk around your bed easily, there is no need for wide rows to access your plants. You can simply space the asparagus crowns 18 inches apart from every other plant. This allows for a greater density of plants in a smaller area while still providing plenty of room for future growth.
Tips For Growing Asparagus In Raised Beds
Here are some tips for growing asparagus in raised beds, and how to maintain them for epic harvests.
Location Is Key
Pick a location in your garden where you do not mind dedicating space to a perennial vegetable for many years. Whether you are growing from established crowns or starting from seed, you will be caring for and harvesting asparagus for a long time, so choosing the right spot matters.
Start with rich soil. Amend the soil with compost before planting to set the bed up for long-term success. Fill the raised bed generously with compost and organic matter, and do not skimp on this step. Asparagus will grow in this raised garden bed for many years, so investing in soil quality from the beginning pays off over time.
Planting Tips
Plant asparagus about 12 inches deep in the soil. Asparagus prefers rich soil and will deplete nutrients over time. Be sure to amend the planting area with organic matter and soil amendments such as compost if you have not already done so. Use a soil mix that is rich in organic matter.
Dig holes 12 inches deep and 18 inches apart. Place the crown or seed into the hole and carefully spread the roots out. Gently push compost over the roots and fill in the hole.
Asparagus can also be planted by digging a trench. Plant asparagus 18 inches apart in the trench and cover with compost and organic matter. The crown should be covered with several inches of soil, between eight and 12 inches. Fill the trench with compost and water deeply.
When starting from seed, you may want to start seeds in containers so they can develop larger root systems before planting out in the garden. Only plant seeds half an inch deep in the soil.
Protecting Young Plants
Protect your young asparagus plants. Do not let the crowns dry out while planting, and keep the bed well watered, especially during the first year. Establishing healthy plants in year one will set you up for stronger growth in the seasons that follow.
In a raised bed, you can easily set up floating row covers to prevent asparagus beetles and other pests from infesting plants before they are fully established.
In addition to floating row covers, you can install a cold frame over the bed in late winter to warm the soil ahead of spring planting. If you need to warm the soil quickly, black plastic can be used to trap heat from the sun. This approach will depend on the zone you are growing in.
If the summer sun becomes too intense, swap the floating row cover for shade cloth to protect the growing fronds.
Growing Your Asparagus
The asparagus plant needs time to establish its roots. When starting from seed, allow three seasons to pass before harvesting any spears. If you plant crowns, you can begin harvesting asparagus spears within the first two years.
Once planted, keep asparagus plants watered with about one inch of water per week. You can set up drip irrigation, a soaker hose, or even use buried clay pots to make watering easier and more consistent. In a tall raised bed, this is even more convenient since you will not have to bend over as much.
Do not waste space in your raised bed. While asparagus does not tolerate root competition well, you can use the space between plants to grow shallow-rooted crops such as spinach and lettuce. The asparagus fronds will provide light shade for leafy greens and help protect them from excessive sun. You can also grow herbs like basil and parsley, or companion plants such as marigolds and tomatoes, which can help repel asparagus beetles.
Weed Prevention
Prevent weeds from invading your bed by mulching deeply, filling any open space with companion plants or cover crops, and keeping the bed weed free by regularly hand pulling weeds before they take over.
It is better to hand pull weeds than to use any mechanical tools. Asparagus roots are delicate, and hand pulling helps protect them from accidental damage.
Regularly removing weeds prevents crowding and competition around the asparagus roots. If weeds are an ongoing issue, consider adding companion plants. Filling open spaces in the bed helps block weeds from establishing in bare soil.
Harvesting
Harvesting asparagus is almost an art form. In the first few years, you should harvest only a few spears within a two-week period. After that, allow the asparagus fronds to develop and do not harvest any more spears. If you harvest too many spears early on, the plant will not develop the strong root system it needs to survive long term.
In the following years, increase the length of your harvest period by one week each season. For example, in your third year, you can harvest spears for three weeks. After that, stop harvesting and allow the plant to grow out its fronds fully.
The longest you should harvest asparagus is ten weeks. Keep in mind that this is a plant that can live for decades, so giving it time to recover after harvest is essential for long-term productivity.
Post-Harvest Maintenance
Once you finish harvesting asparagus for the season, allow the tall fronds to grow out. This helps the plant store energy for the following year. When the fronds turn yellow, but before any red berries drop if you have female plants, cut the fronds back to within a few inches of the soil.
If you live in a climate with harsh winters, leave the fronds in place through winter for extra frost protection. In spring, remove the fronds and add them to your compost pile or dispose of them so overwintering pests do not become established.
After the fronds are removed and the soil begins to warm, top dress the bed with a layer of compost to support new spring growth.
Mulch heavily to retain soil moisture, but wait until the weather has warmed. Mulch can cool the soil, and asparagus needs warm soil to kickstart early spring growth.
Planting asparagus in a raised garden bed can be a rewarding long-term project with many advantages over growing at ground level. A well-planned asparagus bed helps simplify fertilizing, watering, and pest control while remaining easy to access and maintain, especially in tall raised beds. With these tips, growing asparagus successfully should be well within reach.
