With a little bit of effort, asparagus can be grown in a container, and this article would show you how to grow asparagus in a container.
Asparagus (Asparagus officinalis) is a hardy, perennial vegetable that serves as a wonderful addition to indoor gardens as well as permaculture food forests. They are typically cultivated in plant hardiness zones 3 – 10 for their tender edible shoots.
Generally, asparagus are planted outdoors in gardens because ample space is needed for the plants to flourish. However, it’s also possible to grow asparagus in pots or containers. This is a relief for avid gardeners who’d love to plant them but are limited to just balconies or indoor spaces.
The good news is that with several new cultivars available, growing asparagus in a container or pot is a lot easier than before. This article is a detailed guide on how to nail the process from seedling or crowns to maturity. Read on to learn everything you need to know on how to grow asparagus in a container.
How to Grow Asparagus in a Container
Compared to other kitchen garden plants, asparagus are slow-growers. It takes about 2 – 3 years for the plants to reach maturity when grown from seeds. And about a year or less when grown from crowns because they have a year or two headstart compared to seeds.
Like most plants grown in containers, there are vital steps to follow when planting asparagus in containers. These include choosing where to locate the container, picking the right container, deciding which asparagus variety to plant, soil considerations, and the proper plant management and care routine.
Growing Asparagus in Containers: Choosing the Location
Asparagus plants need at least 8 hours of daily exposure to full sunshine. For this reason, the ideal spot to should get this level of exposure to sunlight daily even in winter.
If you have to grow container asparagus indoors due to limited outdoor space, the best spot is most likely a window that receives the best exposure to sunlight.
However, while asparagus can thrive indoors, it would require cooler temperatures during winter for the dormancy period. This makes it vital to find a good location outdoors to relocate the container in winter.
Choosing the best Container to Grow Asparagus
Getting this right is probably the most important decision you’d make if you want the asparagus to thrive.
The average height of a matured asparagus is between 5 and 9 feet tall. The matured foliage can spread as wide as 3 feet. These dimensions are too large for the average container/planter.
So you are looking at very large containers of at least 20 inches in depth and 20 inches wide. You can go bigger because when it comes to using containers to grow asparagus, bigger is always better.
You can use terra cotta or plastic containers of the required size. Plastics are more popular: apart from being cheaper, they don’t break easily.
Finally, drill several drainage holes at the bottom of the container if it doesn’t have them. Without drainage holes, the plant becomes susceptible to fatal diseases.
Asparagus Soil Requirements
To get the best results, fill the pot with a high-quality potting mix. Don’t use garden soil.
Potting mix can be purchased from the local garden store or a commercial farm. The ingredients to look for in a good potting mix include compost, peat moss, vermiculite, and perlite.
However, if you don’t have access to a garden store, you could make a potting mix at home. The are several useful guides online on how to make a good potting mix suitable for your needs. You’d be surprised how easy it is.
Use a pH test kit to ensure the soil pH is between 6.5 and 7.5. Amend the soil as desired to either decrease or increase the pH if the test result shows the soil pH is outside that range.
Sulfur can be used to lower the pH while you can use lime to increase the pH. These ingredients can also be purchased from a garden store near you with instructions on how to use them to amend the soil.
Finally, consider adding compost to the soil. This helps to improve soil drainage while making more organic nutrients available to the asparagus.
Best Time to Plant Asparagus in Container
Spring is the best time to plant asparagus. You might think of starting earlier if the growing season in your region is comparatively short. You could plant the seeds indoors and then transplant the seedlings when they are about 3 inches high. And if you go down this route, wait until the last frost before transplanting the seedling outdoors to your containers.
Asparagus plants grow from spring right through to fall and then hibernate in winter. Though it goes dormant in winter, it would resume growing again in spring because the roots don’t die out during the dormant stage.
How to Plant Asparagus in Containers
Asparagus can be grown in containers from seeds or existing crowns. With seeds, it takes at least 2 years for the plant to reach maturity, while it takes about a year less to reach maturity with crowns.
The first consideration though is choosing the right asparagus variety to plant.
Choosing asparagus variety to grow in a container
Though any asparagus variety would thrive in a container with the right care, male asparagus is recommended. Compared to female asparagus, male varieties like Mary Washington, Jersey Giant, Jersey King, and Jersey Knight, produce bigger spears and better yields.
Also, female varieties tend to expend energy on seed production leading to smaller spears. Another factor that counts against females is that the produced seeds easily sprout into new seedlings leading to overcrowding.
Finally, many of the new male asparagus hybrids are designed to be cold-tolerant and better at resisting fusarium and rust.
Planting asparagus seedlings in a container.
- Get the seeds from the local garden store or nursery. You can also order them online.
- Soak the seeds in warm water for about 24 hours. This promotes faster germination.
- Dig a hole about half an inch deep. Place a seed in each hole and cover it with the potting soil.
- Spray water on the soil. Never allow the soil to become dry; always ensure the soil is moist.
The seeds would germinate in about 2 – 3 weeks. The plant would take the next year growing and developing strong roots.
- Ensure the container is located in a spot with the ideal temperature range (65 – 85°F) of growing asparagus.
However, if you live in a region where summers are very hot and dry, look for a location that is sheltered from the midday sun so that each plant gets only filtered light at this time of the day.
Planting asparagus crowns in a container.
- Dig a small trench about 18″ wide and 8″ deep. It has to be this size to give enough room for the crowns to rest.
- Place the crowns, root first, into the hole. Ensure the roots are spread out while doing this.
- Cover the crowns with about 3″ of the potting soil.
- Water the crowns deeply. Keep watering until excess water drains out of the drainage holes.
Taking Care Of Asparagus in Containers
Asparagus thrives best with 6 – 8 hours of daily exposure to full sunlight. Though it can grow in partial shade, growth would be slower.
You want the temperature to be at around 65 – 85°F. Anything below that would be detrimental to the production of spears. Above that range, you can expect to harvest matured asparagus with subpar quality and flavor.
In the first few years of growth, asparagus needs lots of water. Endeavor to keep the soil moist frequently.
Check for soil moisture level daily by sticking a finger about 2 inches into the soil. If the top of the finger feels dry, the soil needs more water.
When watering, don’t stop until water starts flowing out of the drainage holes. This deep watering technique ensures water reaches all parts of the soil to promote the development of a robust root system.
If you have a few containers, a watering can would be adequate. But consider setting up an irrigation system with a timer if you have many containers since manual watering might be tedious.
Early mornings are the best times to water asparagus. This ensures that your asparagus absorb the needed water before losing some of it to evaporation in the afternoon sun.
Finally, aim to achieve a balance between underwatering and overwatering. Too much water (soggy soil) can lead to root rot that is very fatal to asparagus.
Asparagus plants are generally nutrient-hungry. That’s why it was important adding compost and manure while preparing the pot. In terms of additional nutrients, adding compost or manure around the plant once a month would be great.
If you have to use inorganic fertilizer, consider using a balanced formula (NPK 5-10-10, 10-10-10, or even 15-15-15) around the plant. Do this in spring immediately after planting. The asparagus would use that for several months.
Remember to read the instructions carefully before applying your fertilizer.
Harvesting your container Asparagus
The right time to harvest the asparagus depends on whether seeds or crowns were used to grow them. If you started with seeds, it would take at least 2 years, while starting with crowns takes at least a year.
In the first year, you can harvest the matured spears for about 2 – 4 weeks when they are between 6 – 9 inches high. In subsequent years, harvesting could last 8 weeks in the growing season.
When you are ready to harvest, simply use a sharp knife, a pair of garden scissors, or pruners to cut the spears at the base. Don’t cut below the soil to avoid damaging the roots.
The stem below the soil would grow new spears that you can harvest throughout the growing season.
Asparagus plants are usually grown in the garden. But for those with no garden space, growing asparagus in a container is an option. Fortunately, with the availability of many hybrid asparagus varieties suitable for container growing, the whole process from young sprout to matured plants is easier.
The plants take about two years to mature depending on whether seeds or crowns were used as starters. However, unlike garden asparagus that can be harvested for up to 10 years, asparagus grown in containers stop producing new spears about 3 years after maturity.