Asparagus is generally grown in open ground, and let me start by saying that this is also where it grows most easily. However, if you don't have space for asparagus in open ground, or if, for example, you have heavy clay soil that asparagus doesn't like, then growing it in a pot or container can be an option for growing your own asparagus nonetheless.
Asparagus are perennial plants that come back every year. In terms of growth, you can compare them somewhat to rhubarb. Every year you can harvest the foliage until midsummer (June 21st), after which you must stop harvesting from the plant. The foliage that grows after midsummer is important because the plant uses it to draw energy and store it in its roots. This ensures the root has enough energy to survive the winter and produce plenty of asparagus again in the spring. As perennials, asparagus and also rhubarb remain in the same spot in your garden for a long time. Asparagus can provide good yields for up to 20 years if you take good care of them. But because a lot of energy must be stored in the root, the root also needs enough room to grow well.
What kind of pot or container do I need?
In open ground, the asparagus plant can grow unhindered, but that is not the case in a pot or container. To give the asparagus plant enough space, you must use at least a pot or container with a capacity of 60 litres. The pot must be able to hold at least 40 cm of soil to grow asparagus properly. Many people use a 60-litre or even 90-litre mortar tub. The advantage of mortar tubs is that they have a good height-to-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 still grow well in width. A 60-litre mortar tub fits two plants; a 90-litre mortar tub fits three. But any other large pot or homemade container will of course also work just 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 light and well-draining soil, such as the sandy soil in which they are grown in open ground. So, ensure your pot can drain well, and in the case of a mortar tub, drill sufficient holes in the bottom of the tub. At the bottom of the pot, you can start with a layer of coarse gravel to help the pot drain well. Furthermore, fill the pot with high-quality potting soil and optionally supplement this with 1/3 compost.
Nutrition
After midsummer, asparagus needs a lot of energy to be able to sprout again every year and survive the winter well. The nutrients in the pot become depleted over time, so you must ensure they are replenished. This can be done by adding a fresh layer of compost to the pot every spring and providing some extra nutrition during the season in the form of organic granules or a liquid fertiliser that you can add to the watering can.
With the right pot, the right soil filling, and good-quality asparagus crowns, your asparagus will shoot out of the ground in the spring, but you will still have to wait a little while before you can harvest them. You can read more about that in this blog.
