Asparagus is generally grown in the open ground, and let me start by saying that asparagus grows easiest there. But if you don't have room for asparagus in the open ground, or if you are on heavy clay, for example, which asparagus doesn't like, then growing in a pot or container can be an option to still grow your own asparagus.
Asparagus are perennials that return every year. In terms of growth, they can be compared to rhubarb. Every year, you can harvest the foliage until the longest day (June 21), and after that, you may no longer harvest from the plant. The foliage that grows after the longest day is important because the plant gets energy from it and stores this energy in its roots. This gives the root enough energy to survive the winter and to produce plenty of asparagus again in the spring. Asparagus and rhubarb are perennials, so they stay in the same place in your garden for a long time. Asparagus can produce well for 20 years if you take good care of them. But because a lot of energy has to be stored in the root, the root must also have enough space to grow well.
What kind of pot or container do I need?
In the open ground, the asparagus plant can grow unhindered, but in a pot or container this is not the case. To give the asparagus plant enough space, you should use a pot or container with a capacity of at least 60 litres. The pot should be able to contain at least 40 cm of soil in order to grow the asparagus well. Many people use a 60-litre or even 90-litre mortar tub. The advantage of mortar tubs is that they have a good height/width ratio and are not too expensive. The containers are exactly high enough to plant the asparagus at the right depth, and the roots can also grow well in width. Two plants fit in a 60-litre mortar tub, and three plants fit in a 90-litre mortar tub. But another large pot or homemade container will of course also work fine, as long as they have a minimum capacity of 60 litres and are at least 40 cm high.
Filling the container
You now have the right pot or container, but what are you going to fill it with? Asparagus likes airy and well-draining soil, such as sandy soil in which they are grown in the open ground. So make sure that your pot can drain well, and in the case of a mortar tub, drill enough holes in the bottom of the tub. At the bottom of the pot you can start with a layer of coarse gravel to allow the pot to drain well. Then fill the pot with quality potting soil and if necessary fill it with 1/3 compost.
Power supply
Asparagus needs a lot of energy after the longest day to be able to grow again every year and to survive the winter well. The nutrients in the pot are depleted over time, so you have to make sure that they are replenished. This can be done by putting a fresh layer of compost on the pot every spring and providing some extra nutrition during the season in the form of organic granules or a liquid nutrition that you can give with the irrigation water.
