|I would like to grow a Christmas tree type evergreen in a container on my deck; is this possible? What type of shrub do you recommend, and is a terra cotta pot a good choice? I live in Zone 5.
|Sure it's possible! It's also very attractive and something I have done myself. There are many dwarf conifers that will surely fit the bill. As luck would have it this summer, I put together a very nice half whiskey barrel filled with different shapes and sizes of dwarf evergreens for one of my best friends as a birthday present. I chose the following specimens, you could put together a similar grouping, or choose a single variety. Here they are: Picea abies 'Little Gem', reaches a height of approx. 1 ft. with similar spread; Picea glauca 'Rainbow's End' (also known as Dwarf Gold Tipped Alberta Spruce), grows to 3-4'; and, a variety of "Creeping Juniper" (Juniperus horizontalis) known as 'Mother Lode',it is only about 3" high, has a ground cover habit and should eventually spill over the sides. You could also consider Chamaecyparis obtusa 'Nana Lutea', Dwarf Canadian Hemlock, or Pinus peuce 'Arnold's Dwarf'.
A terra cotta pot would be fine as long as it is large enough, and if you keep in mind terra cotta containers are porous and dry out quickly. They are also prone to cracking during freeze/thaw cycles. You might be better off with wooden whiskey barrels or plasticpots made specially for outdoor plantings.
Regarding size of the pot - the best case scenario would be to plant in a container about twice as wide and deep as the rootball of the plant. Remember, those roots need a lot of room for expansion. Also, mulch the plant well to help insulate it from thawing during a warm spell--the soil in containers is exposed to warm air on all sides and warms up much faster than soil in the garden. If the plants warm up too much they could break dormancy and put out new growth too early. If you have several planters, cluster them together to create a more constant microclimate--you can even insulate the containers with hay.