Growing asparagus in raised beds is quite easy, and this guide would walk you through how to grow asparagus in raised beds. For some gardeners, the idea of waiting up to three years before they can harvest asparagus spears nudges them to take a pass on growing some. They assume it’s three years of backbreaking work. How wrong can they be? Asparagus is literally at the top of the pack of some of the easiest perennial veggies to grow.
The long time interval before harvest is correct though. But most of that time is filled with very little, routine, gardening tasks. And you don’t even have to do them daily.
Growing Asparagus in Raised Beds
Asparagus are perennial plants typically grown in zones 3 – 8. They thrive best in full-sunshine of at least 6 hours daily. But they wouldn’t do too badly in partial shade. Sunlight though is very essential for the roots to become established.
Though they are perennials that grow year after year starting from early spring, they also enter a period of dormancy in winter when they seem dead. Actually, they are only hibernating until the following spring. If everything is done right, you’d harvest the spears every year for up to 20 years before they enter the dormancy period.
How to Grow Asparagus from Cuttings
When it comes to growing asparagus in raised beds, a basic step of the process would look something like this:
- Build and prep the raised bed
- Get the asparagus crowns
- Plant the crowns
- Care and maintenance
- Harvest mature spears
Asparagus growers using raised beds would tell you building the raised beds and planting the crowns are the most difficult parts. After that, it is plain sailing to harvest the spears annually for over two decades.
We would now walk you through each of those stages.
Building and prepping your raised bed
First of all, we encourage you to take some time to figure out where the bed is going to be; and then put in the time and effort to prepare the raised bed. This is because that asparagus bed would be in that spot for 20 or more years. For this reason, consider building the asparagus bed where it won’t interfere with other garden activities.
Ensure that the raised bed is located where the soil is already rich with nutrients and free of weeds. If there are weeds, eradicate them. You can amend the soil with compost to get it up to the required standard. Adding perlite would also be great to improve drainage
The raised bed would now be built on this patch of land.
Stages of Growing Asparagus [From Seed/Crown to Harvest]
Constructing the raised asparagus garden bed
Since we are thinking long-term here, the type of lumber used for constructing the raised bed is important. You don’t want to use wood that decomposes easily. Old pine and red cedar are good choices.
Other woods you can use if you don’t have pine or cedar are cypress, redwood, and spruce. All these can survive the test of time.
One final point about the wood. Make sure it is untreated wood. Woods treated with chemicals can easily release these harmful chemicals into your soil.
In terms of the dimensions of your rectangular raised bed, that depends on how much asparagus you wish to plant. The wood itself should be 2 by 12 inches high. That means, the raised bed should be at least 12 inches high from the ground.
Filling up with soil
Fill your already built raised bed with soil. The preferred soil should be a great blend of rich loamy soil, compost, and lots of organic manure.
You can also add some slow-release, balanced organic fertilizer before planting. But if you added enough compost and manure to the soil, this won’t be necessary.
Some folks opt to get store-bought potting soil and simply add manure and other organic nutrients. This is also a great choice.
The heavy lifting is over. Now is time to plant your asparagus.
Planting your asparagus crowns
The best time of the year to plant asparagus is the beginning of spring when the soil has warmed up to about 50°F.
First, you want to put in the order for your asparagus crowns early from a reputable store. It’s best to schedule your asparagus crowns order so it arrives just in time for the planting season.
The are several species of asparagus. For your needs though, we recommend sticking male varieties such as Jersey Knight, Jersey Supreme, or Jersey Giant.
When you get the plants, they might be a little brittle and dry. Soak them in a bucket of water for one or a couple of hours before planting them.
There are two ways to plant the asparagus in the raised bed. The traditional way is to dig a 6 – 8 inches trench, place the asparagus crowns in the trench, and cover the asparagus with 2 inches of soil. Then a couple of weeks later, after sprouting, add another 2 inches of soil, repeat until the trench is filled up.
How to Grow Asparagus in a Container [Ultimate Guide]
While this method is okay, it takes time and you don’t really need it for raised beds.
The second method is quite easy and you’d be done planting your asparagus in a day.
Simply follow these steps:
1. Using your hand or a garden trowel, dig a hole about 6 inches deep and 8 inches wide on your raised bed
2. Placed an asparagus crown inside the hole with the roots downwards. Make sure the roots are spread nicely apart.
3. Cover the hole and asparagus completely with the garden soil.
4. Repeat step 3 with another hole about 18 inches from the first hole. Keep doing this until you’ve planted all the asparagus crowns making sure the plants are 18 inches apart.
5. It’s better to plant them in rows and the distance between each row should be about 18 inches too.
6. After planting, water your asparagus deeply. Be careful not to overwater. Stop when the water starts gathering at the top. Too much water or soggy soil can cause root rot. The water should drain down to the soil underneath the raised bed leaving the raised bed evenly moist.
7. Mulch the bed. You can use leaves and grass clippings. Then add a layer of hay mulch on top. The mulch helps to lock in the moisture in the soil and prevent the growth of weeds.
Quite easy right? All you need to do throughout the first growing season is to make sure the soil never gets dry. So you might want to test the soil moisture regularly by poking your fingers into it every few days.
If you live in a hot, dry region, you just need to water once a week or depending on the weather. But when it rains, there is no need to water.
Harvesting and post-harvest care
In the first season, you have two options: you can harvest the spears or allow them to grow out without harvesting. If you decide to harvest the spears, do it for about 4 weeks. Keep in mind that the spears at this stage are not the best version of what you want them to be.
If you decide not to harvest, simply allow the plants would grow out to their full height. The ferns, using the sun, produce energy that is stored in the crowns and roots beneath the soil. This energy is used to kickstart the plant in the next growing season.
In fall, the plants would turn brownish and the foliage above the soil would die off. This is the dormancy period. Simply snap off the stems leaving the roots and corns in the soil. Then add about 3 inches of your preferred mulch to prevent the growth of weeds. This is the winter care routine to follow annually after the growing season.
In the second growing season, your asparagus are now full established and would start producing nice, thick spears. The width of a matured spear should be more than half an inch at least before harvesting. The best size, width-wise, should be about the thickness of an adult’s pinky finger.
Start to cut the asparagus before the tip of the spears start to open up; that should be when they are about 6-8 inches high. If you allow the ferns to open up at the tip, it would become too woody to enjoy eating. Keep in mind that they grow fast, so keep eye on the asparagus garden. Harvest regularly to promote the production of more spears.
Use a pair of scissors or garden pruners to cut each spear just a few inches above the soil. You can even snap each one off with your hand if you don’t have these tools. Just remember not to pull the spears upwards to avoid stressing the asparagus roots.
After harvesting the matured spears for several weeks {about 8 weeks or so), quit harvesting and allow the asparagus plant to grow out. This is the period where asparagus is awesome as an ornamental plant. You’ll love the ferns.
Then simply switch to the winter care mode described above.
When spring comes around again, you can top dress the bed with about an inch of compost and manure. This gives the plants a rich base of nitrogen-rich and nutrient-packed soil to feed off throughout the growing season. Other materials you could use to enrich the soil include organic blood and bone.
Finally, water the bed deeply. The young sprouts would pop out of the soil in about a couple of weeks to restart the cycle. And this is all you have to do to ensure harvest healthy, fresh asparagus spears for the next couple of decades.
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Wrapping up
And there you have it! Growing asparagus in raised beds can be an exciting adventure and has many advantages over planting at ground level. A well-planned raised asparagus bed can solve several fertilizing, watering, and pest control needs. And it’s easy to access and maintain.
The hardest part is waiting. Even building the raised bed isn’t so difficult. Outsourcing this stage is an option if your carpentry skills are not great. And if you can hold out for just a couple of years tops, you’ll have an asparagus patch that produces tasty spears for up to two decades or more!
