Growing asparagus in a raised bed requires a location that receives at least 8 hours of full sun each day. Once you’ve chosen a location, construct a raised bed in whatever size you desire—asparagus plants only need 2 square feet each so they can be grown in small spaces. Fill your raised bed with a mix of soil, compost, and potting soil. Then, plant one-year-old asparagus root crowns. Provide them with 1–2 inches of water weekly. Once the plants have established themselves, you can begin harvesting asparagus from your garden.
Can Asparagus Survive in Raised Beds?
Not only will asparagus survive in a raised bed, but it will also thrive there. Planting asparagus in a raised bed allows you to plant in high-quality soil that you control. This means you can create a well-draining environment that eliminates crown rot and other common asparagus diseases.
- Asparagus grows extremely well in a raised bed.
- Planting in a raised bed allows you to mix fertilizers into the soil for added growth.
- Planting asparagus in a raised bed helps to prevent crown rot and other diseases.
Although asparagus can be grown directly in the ground, a raised bed allows you to create a controlled environment with well-fertilized soil so your new asparagus plants receive a jump start. Planting in a raised bed also makes it easier to implement special tactics to keep weeds out of your asparagus.
7 Steps to Grow Asparagus in Raised Beds
Everything you need to know about growing asparagus in a raised bed is covered below. From where to position a raised bed, to the ideal dimensions for an asparagus bed, how far apart to plant asparagus, and how to care for your plants. Just follow the steps below to grow amazing asparagus.
Pick a Sunny Location
Asparagus needs 8 hours of full sun daily. So, whether you are constructing a new raised bed or using an existing bed, plant in an east, west, or south-facing location. Avoid planting in an area where the raised bed is cast in heavy shade during the morning or early afternoon.
- Asparagus thrives when it receives at least 8 hours of direct sunlight per day.
- Choose a sunny location for your raised bed.
- Avoid planting in areas shaded by buildings or trees.
Ideally, asparagus should receive uninterrupted morning sun and at least some direct sunlight in the afternoon. All-day direct sun is also good for asparagus, so you don’t need to worry about providing shade in most conditions.
How Big Should a Raised Bed Be for Asparagus?
The size of the raised bed you use for asparagus depends on how much asparagus you want to grow. Each plant needs 12 inches (30 cm) of space from the sides of the bed and all other plants for adequate growth. Additionally, rows of asparagus should be planted 24 inches (60 cm) apart. This means you can plant up to 14 asparagus plants in an 8-foot by 4-foot raised bed. A 4-by-4 raised bed can accommodate up to 6 asparagus plants.
- Asparagus can be grown in large or small raised beds since they only need 12 inches (30 cm) of space from raised bed walls and other plants.
- An 8-by-4 raised bed can support 16 asparagus plants, which will produce a very large harvest.
- You can plant asparagus in a raised bed alongside tomatoes and other vegetables.
You do not need to fill your raised bed with asparagus only. Asparagus grows well alongside many other vegetables. In fact, planting asparagus and tomatoes together in the same bed can benefit your plants. Tomatoes produce a natural compound called solanine that drives off pests such as asparagus beetles.
How Deep Does the Soil Need to Be for Asparagus?
Asparagus requires very deep soil, but it can be grown in raised beds 12–24 inches (30–60 cm) tall. To do this, just make sure there is no barrier between the bottom of the raised bed and the soil below. This allows you to fill the raised bed with high-quality soil that will feed young asparagus plants, but it also allows asparagus to send its deep roots far into the soil.
- Asparagus needs deep soil but does not need a very tall raised bed.
- Because asparagus roots can grow as deep as 15 feet (4.5 meters), do not put any barrier beneath your raised bed.
- A 12–24-inch tall (30–60 cm) raised bed is perfect for asparagus.
- The upper soil of the raised bed will feed young asparagus, boosting plant health.
- No barrier between the raised bed and the soil below allows asparagus to grow deep, healthy roots.
You may be surprised to learn how deep asparagus roots can grow. They can reach depths of 15 feet (4.5 meters). Since raised beds are not this tall, it’s essential that you do not put any landscape fabric at the bottom of your raised bed. Putting any sort of barrier beneath your raised bed can stop the roots and cause your asparagus to suffer.
Asparagus requires soil rich in nitrogen, potassium, and phosphorus in order to thrive. To accomplish this, follow these steps for filling your raised bed with soil:
- Pour 100 pounds (45 kilos) of topsoil into the raised bed.
- Add 50 pounds (23 kilos) of aged compost to your raised bed.
- Add 10 pounds of potting soil mix with vermiculite to the raised bed.
- Mix the ingredients together with a rake, hoe, or shovel.
- Repeat until the bed is filled almost to the top.
- Add 1 pound of this balanced fertilizer for every 100 square feet of raised bed.
- Water the fertilizer into your soil mix.
By gradually adding and mixing your soil ingredients, you will end up with a bed of well-mixed, high-quality soil. A high-quality topsoil is a good start, but the compost and fertilizer provide much-needed nutrients to asparagus. Plus, the potting soil improves drainage and prevents waterlogged asparagus.
Asparagus must be planted in spring. Because asparagus is a hardy plant, you can plant in early spring, as soon as the danger of frost has passed. While you can grow asparagus from seeds, you’ll get a harvest sooner by buying and planting one-year-old bare root crowns. These crowns grow best when they are soaked in room-temperature water or compost tea for 5 minutes prior to planting. Then, dig a hole deep enough for the roots and leave the crown exposed above the soil.
- Plant asparagus in early spring, 1–2 weeks after the last spring frost.
- One-year-old bare root crowns are the best choice for planting in your raised bed.
- Soak the roots of the asparagus in water or compost tea for 5 minutes prior to planting.
- Dig a hole large enough for the roots and plant them, leaving the crown exposed.
- Space asparagus plants 12 inches (30 cm) from raised bed walls and neighboring plants.
- Allow 24 inches (60 cm) of space between rows of asparagus.
Plant your asparagus crowns in rows, with 12 inches (30 cm) between each plant. The asparagus plants should also be 12 inches from all walls of the raised bed. If you are planting more than one row of asparagus, space the rows 24 inches (60 cm) apart.
How much water your raised bed asparagus needs depends on the age of the plant. If you plant one-year-old bare root crowns in your bed, provide 1–2 inches (2.5–5 cm) of water per week for the first year. Then, reduce watering to 1 inch (2.5 cm) per week after the first year.
- Water raised bed asparagus with a soaker hose for best results.
- 15–30 minutes of watering once per week is typically enough for asparagus.
- Bare root crowns typically require additional water for the first year after planting, until they become established.
Be sure to read our detailed asparagus watering guide for more information. However, 15–30 minutes of watering with a soaker hose once per week is ideal for asparagus grown in a raised bed. Make sure to increase the watering frequency if your asparagus begins to yellow or wilt.
Wait to Harvest
Patience is a must when growing asparagus. For the first 2 years after planting your asparagus, do not harvest any of the spears your plants grow. This waiting period creates stronger asparagus plants that produce far more spears long-term. However, asparagus is well worth the wait.
- Do not harvest newly planted asparagus for the first 2 years.
- Beginning in year 3, harvest asparagus spears when they grow 4–10 inches (10–25 cm) tall.
- Break asparagus spears off by hand or cut them off at ground level to harvest.
- Do not leave any stubs of asparagus spears standing above ground level after harvesting.
Once your asparagus has been allowed to grow for 2 years, begin harvesting in year 3. Harvest asparagus when the spears are 4–10 inches (10–25 cm) tall. It’s best to harvest them by hand by breaking or cutting the spears off at the soil level. Don’t leave any stubs poking above the soil. By following this process, you’ll get an abundant harvest for many years. Each asparagus plant can produce spears for up to 20 years.
How Do You Raise Asparagus in a Raised Bed?
To grow plenty of asparagus in a raised bed, follow this process:
- Build or repurpose a raised bed in a location that receives full sun for 8 hours per day.
- Your raised bed can be large or small—each asparagus plant only needs 12 inches (30 cm) of space from walls and other plants.
- Do not put a barrier between the bottom of the raised bed and the soil below—asparagus grows roots that extend as far down as 15 feet (4.5 meters).
- Fill your bed with a soil mix of 6 parts topsoil, 3 parts aged compost, and 1 part potting soil.
- Plant one-year-old asparagus root crowns in rows with 12 inches (30 cm) between plants and 24 inches (60 cm) between rows.
- Water asparagus plants with up to 2 inches (5 cm) of water per week for the first year. Then, reduce watering to 1 inch (2.5 cm) per week.
- Do not harvest asparagus spears for the first 2 years after planting. Beginning in year 3, you can start harvesting.
Asparagus is a hardy plant that can survive harsh winters and bounce back year after year. Even better, established asparagus is very hard to kill. By following the steps in this article, you’ll create a low-maintenance asparagus bed that produces fresh vegetables for 15–20 years.