Asparagus is a long-lived perennial vegetable that grows in USDA zones 3-8. It requires rich, well-drained soil, consistent moisture, and no weed competition. What better place to grow asparagus plants than in a raised bed where you can easily fill it with organic matter and control the planting conditions! Asparagus can easily live for 20 years, so you will need to plan the location of your asparagus raised bed carefully.
The benefit of planning out your asparagus bed is that you can easily control many of the conditions that asparagus plants like, and make the maintenance of your bed over the long term easy to keep up with. Asparagus can be started from seed, but it is most commonly planted in the garden as crowns that are two years old and have long roots.
With a few simple steps, you can set yourself up for decades of gardening in an easy to reach raised bed! Growing in a raised bed will help you control the soil quality and moisture over time as well. If you would like to learn about the benefits of growing asparagus in a raised bed, then keep reading!
Why An Asparagus Raised Bed?
There are many reasons why you should grow your asparagus in a raised bed garden.
Soil quality: Because you fill the raised bed yourself, you are able to use a much higher quality soil than what you would be using for in-ground planting. It’s much easier to amend the soil in the entire bed from the start, and you have complete control over how much compost and which soil amendments you add. Additionally, the soil in a raised bed will have good drainage, which protects the root system from rot.
Ease of care: A raised bed is easier to manage on a day-to-day basis because there are much fewer weeds in a raised bed, and they can be hand-pulled easily. Taller raised beds will also require less bending over! You can easily install drip irrigation or a soaker hose system that will reduce the time you have to spend watering your plants.
Protection for perennials: Asparagus will come back year after year, so you can easily protect them in a separate bed. This means if you need to use raised bed covers to protect the plants from pests or wildlife, you don’t have to worry about harming any other plants near them.
Optimizing for your plant type: Another benefit of a raised asparagus bed is that you can optimize the conditions just for asparagus without having to worry about other plants near them. This could include things like your watering and fertilizing schedule, when and how much you mulch, and the types of row covers you use over your plants.
More rapid soil warming: This is important because asparagus is often one of the first crops to emerge in early spring, but it needs warm, sheltered soil to do so. By planting in a raised bed, your soil will warm up faster than in ground, and you can use different covers to speed up the warming process and protect the plants from any sudden temperature changes. This helps give your asparagus a head start over plants that are in the ground.
Style: In addition to being functional, raised asparagus beds can also add style to your garden! Since asparagus are perennial, they can be a featured plant in your garden. Consider placing your asparagus bed somewhere where you can show off the wispy asparagus “ferns” in the summer season, or use them as a fun conversation starter!
Longevity: One reason why using a raised bed is useful, especially a modular style made out of galvanized steel like the beds in the Epic Gardening store, is because metal beds can outlast wood beds. A wooden bed will eventually rot and disintegrate. However, metal beds, especially well-made ones, should last for decades… just like your asparagus plants!
Ease of harvest: Last but not least, harvesting asparagus from a tall raised bed is much easier than picking it from the ground. In a tall bed, you can just walk by and break spears off as they grow!
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 plant lots of room to spread out, and room for you to walk along the rows and access your plants as you care for them.
In a raised bed, you don’t have to space the “rows” so far apart! Because you can walk around your bed easily, there is no need for large 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 allowing 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. There are not many specialized supplies you will need.
Location Is Key
Pick a location in your garden where you don’t mind dedicating space to growing a perennial vegetable for a long time. Whether growing an older plant or starting from seed, you will be caring for (and harvesting) this plant for a long time.
Start with rich soil. Amend your soil with compost before you even plant your plants. That way, you are setting yourself up for success! Fill the bed with compost and organic matter. Make sure you don’t skimp on this part as asparagus will grow for a long time in this raised garden bed.
Plant asparagus about 12 inches deep in the soil. Asparagus likes to grow in rich soils, and will deplete the nutrients over time. Be sure to amend the planting area with organic matter and soil amendments like compost if you haven’t already done so. Use a soil mix 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 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 8 and 12 inches. Fill the trench with compost and water deeply.
When starting from seed, you may want to start your seeds in containers so they can grow bigger roots before planting out in the garden. Only plant seeds half an inch deep in the soil.
Protecting Young Plants
Protect your young asparagus plants. Don’t let the crowns dry out while you are planting, and keep the bed watered well, especially during the first year. Establishing healthy plants in the first year will set you up for greater growth over the following seasons.
In a raised bed, you can easily set up floating row covers over the bed to prevent the asparagus beetle or other pests from infesting your plants before they are established.
In addition to using floating row covers, you can set up a cold frame over the bed in late winter to warm the soil for spring as needed. If you need to warm your soil up quickly, use black plastic to trap heat from the sun. This will depend on which zone you are growing in.
If the summer sun gets too hot for the asparagus, swap your floating row cover for some 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 you harvest any spears. If you plant crowns, you can harvest asparagus spears within the first two years.
Once they are planted, keep your asparagus plants watered with about 1 inch of water per week. You could set up drip irrigation, a soaker hose, or even use buried clay pots to make watering more convenient. In a tall raised bed, this will be even easier because you won’t have to bend over!
Don’t waste space! Asparagus hates root competition, but you can use the space between your plants to grow shallow rooted crops like spinach and lettuce. The asparagus fronds will shade the leafy greens and protect them from too much sun. You can also grow herbs like basil and parsley, or marigolds and tomatoes, which help repel asparagus beetles.
Prevent weeds from invading your bed by mulching deeply, filling any open space with companion plants or cover crops, and make sure the bed is weed free by regularly hand-pulling weeds to stop them from taking over.
It’s better to hand pull weeds than to use any special machinery. Asparagus roots are delicate, and you want to protect them from any damage.
Regularly pull any weeds to protect the delicate asparagus roots from crowding or competition. Consider planting companion plants if you struggle with weeds, as filling the bed with plants will block out weeds from growing in empty spaces.
Harvesting asparagus is like an art form! In the first few years, you want to harvest just a few spears within a two week period. Then, allow the asparagus fronds to develop, and don’t harvest any more spears. If you harvest too many spears early on, your plant won’t develop the strong root system it needs to survive.
In the following years, increase the number of weeks that you harvest spears for by one week. For example, in your third year, you could harvest spears for three weeks, but after that, you should stop and allow the plant to grow out its fronds.
The longest you should harvest your asparagus is ten weeks. Remember, this is a plant that can live for decades, so you want to give it time to recover from the harvest!
Once you harvest your asparagus for the season, let the tall asparagus fronds grow out. This allows the plant to store energy for the next year. Once the fronds turn yellow, but before any of the red berries fall off (if you have female plants), cut the fronds within a few inches of the soil.
If you live in a climate with harsh winters, leave the fronds in place during the winter for added frost protection. In the spring, remove the fronds and add them to your compost or dispose of them so you don’t allow overwintering pests to establish themselves.
Once you remove the fronds and the soil is warming up, top dress with a layer of compost to feed your new spring growth.
Mulch heavily to keep moisture in the soil, but wait until the weather is warmer, because mulch will actually cool down the soil temperature. Your asparagus needs warm soil to start its early growth in the spring.
And there you have it! Planting asparagus in a raised garden bed can be an exciting adventure and has many advantages over planting at ground level. A well-planned asparagus bed can solve several fertilizing, watering, and pest control needs. It is easy to access and maintain, especially in tall raised beds. With these tips and tricks, it should be fairly easy to grow this crop!