Asparagus - Ask Extension
How do you overwinter asparagus growing in five gallon buckets
Knowledgebase
Asparagus #888182
Asked October 17, 2024, 3:30 PM EDT
How do you overwinter asparagus growing in five gallon buckets
Somerset County Maryland
Expert Response
If it's not possible to plant the asparagus in the ground, then all you can do is to insulate the root mass as best as possible and keep an eye on their watering needs. (Don't bring them indoors for the winter...they will not get the dormancy period they need to grow normally, nor would they get enough light to keep growing.)
Plants in containers, even when perfectly cold-hardy in the ground, run the risk of root damage or plant death when kept in a container during winter. This is because the root ball is entirely above-ground and less insulated from temperature fluctuations than they would be growing in the ground instead. Freeze-thaw cycles could injure or kill roots. Container potting soil also dries out faster than soil in the ground (both because it has less volume to store moisture, and because the mix is designed to drain well to protect root health), so plants in pots will need checking for watering during winter to make sure they don't get too dry if rain or snow is insufficient or too sporadic. While the plants themselves aren't using nearly as much water as in summer, the drier air, wind, and sun will still evaporate moisture from the container over time, so how often container-grown plants need checking for water is something you'll have to get used to as you monitor the plants, plus it will vary with the weather.
Just like you would in summer, feel the soil an inch or more (for a 5-gallon bucket, if full of soil, probably 2 or 3 inches) below the surface. If it's become somewhat dry to the touch at that depth, water well so the excess drains freely out of the bottom drain holes. (If the bucket doesn't have drainage, it should be given drainage by drilling holes in the base, or the plant clump moved into a different container that does have drain holes.) If the soil is still damp at that depth when checked, watering can probably wait to avoid over-watering the soil.
If you are able to transfer the plants into the ground, do so soon so they can establish some roots before shutting-down growth during the coldest temperatures. If you can't, or want to keep them in a container, use something around the pot to add insulation so the soil doesn't change temperature as rapidly. Anything adding mass around the bucket will help (bubble wrap or a foam wrap is not enough), such as bags of bark mulch, loose wood chip mulch, intact bales of straw, or even a mound of soil. One in-between alternative option is to "heel-in" the pot, meaning that it's essentially planted without removing the bucket, so the container can be lifted out of the ground in spring. (If the plants do so well that root growth comes out of the bottom drain holes and grows into the soil below, that can make spring removal more difficult, though not impossible.) This method may not work well, though, if the soil it sinks into isn't well-drained, as you don't want extra water backing-up and flooding the roots within the bucket if the soil can't keep up with drainage. Heeling-in potted trees and shrubs is one way that nurseries with unsold inventory overwinters their stock to minimize the risk of winter damage.
Miri
Plants in containers, even when perfectly cold-hardy in the ground, run the risk of root damage or plant death when kept in a container during winter. This is because the root ball is entirely above-ground and less insulated from temperature fluctuations than they would be growing in the ground instead. Freeze-thaw cycles could injure or kill roots. Container potting soil also dries out faster than soil in the ground (both because it has less volume to store moisture, and because the mix is designed to drain well to protect root health), so plants in pots will need checking for watering during winter to make sure they don't get too dry if rain or snow is insufficient or too sporadic. While the plants themselves aren't using nearly as much water as in summer, the drier air, wind, and sun will still evaporate moisture from the container over time, so how often container-grown plants need checking for water is something you'll have to get used to as you monitor the plants, plus it will vary with the weather.
Just like you would in summer, feel the soil an inch or more (for a 5-gallon bucket, if full of soil, probably 2 or 3 inches) below the surface. If it's become somewhat dry to the touch at that depth, water well so the excess drains freely out of the bottom drain holes. (If the bucket doesn't have drainage, it should be given drainage by drilling holes in the base, or the plant clump moved into a different container that does have drain holes.) If the soil is still damp at that depth when checked, watering can probably wait to avoid over-watering the soil.
If you are able to transfer the plants into the ground, do so soon so they can establish some roots before shutting-down growth during the coldest temperatures. If you can't, or want to keep them in a container, use something around the pot to add insulation so the soil doesn't change temperature as rapidly. Anything adding mass around the bucket will help (bubble wrap or a foam wrap is not enough), such as bags of bark mulch, loose wood chip mulch, intact bales of straw, or even a mound of soil. One in-between alternative option is to "heel-in" the pot, meaning that it's essentially planted without removing the bucket, so the container can be lifted out of the ground in spring. (If the plants do so well that root growth comes out of the bottom drain holes and grows into the soil below, that can make spring removal more difficult, though not impossible.) This method may not work well, though, if the soil it sinks into isn't well-drained, as you don't want extra water backing-up and flooding the roots within the bucket if the soil can't keep up with drainage. Heeling-in potted trees and shrubs is one way that nurseries with unsold inventory overwinters their stock to minimize the risk of winter damage.
Miri
