Winterizing Perennials


With respect to the following question I asked before, I live in Sarnia in Southwestern Ontario.

Please advise if and when should I be moving the following potted plants to the garage over the winter:

1) Hosta.

2) Hens & Chicks.

3) Perennial Dwarf Sweet William.



Hostas (Hosta spp.), Perennial Sweet William ( Dianthus barbatus) are hardy herbaceous perennials. They do not produce wood and the stems will die back when the temperature drops below 0C. Hardy herbaceous perennials produce growth at the ground level that forms hardy buds  or a vegetative crown that survives over winter. Hens and Chicks (Sempervivum spp.)are hardy succulent perennials . All the above mentioned perennials  can be removed from their containers transplanted and  over wintered in the garden bed.

If on the other hand you would like to overwinter the perennials in their containers there are 4 different techniques that can be used.

Overwintering success with container perennials is dependent on the ability to insulate the roots in the container. Plants that are grown in containers are exposed to colder temperatures ( at least 2 zones colder)  than those that are grown in the ground.

Method 1, Trench: Dig a trench deep enough so your tallest container is level with the soil lne. Group all your containers together in this trench and fill it with soil.Do this in late fall. Burying the pots will help insulate the roots. Spread evergreen boughs or leaves on top of the containers for insulationDig up the pots in the early spring, or the roots will start to grow out the drainage holes.

Method 2, Knock over the pots: Place planters on their side and group all the planters together in a sheltered area. Cover the pots with leaves to provide extra insulation. This is a particularly good methood for Hostas.Hostas that are usually not lost to the cold but late winter freeze thaws which kills the newly emerging shoots.

Method 3, Bring inside: Store the perennials in their continers in a cool indoor location, eg. a wall in the garage.  It has to be a cool location or the plants will not over winter properly. Move them in the late fall and give one final watering.

Method 4, Protected Location: Move the containers to a protected location outside, such as under an overhang on the eastside of the house. Group the pots close together as possible. Avoid putting the containers on raised structures such as decks because exposure to air below the surface will dry out the roots even faster, killing the plants.

I suggest you contact Sarnia-Lambton Master Gardeners Association who may be more helpful with local issues. They can be contacted .