|I purchased a Japanese Yew which I want to leave in a large planter on our patio. Will it thrive there and how fast do they grow?
If you purchased a Monrovia yew, it may be either Taxus cuspidata 'Monloo' (Moderate- to slow-growing, flat-topped form to 30 inches high, 8 to 10 feet wide) or Taxus x media 'Densiformis' (a slow grower to 3 to 4 feet tall and 4 to 6 feet wide). Both are amenable to careful shearing. You can read more about how to care for both of these plants on the Monrovia Web site under "About Our Plants" and searching using the words Japanese Yew. Neither of Monrovia's selections is labeled as appropriate for container growing, but it really depends on just how large the planter is. Ultimate size of the plant will be limited by the container's size.
According to the USDA Zone map, you're in zone 6, so the soil in the planter is likely to freeze, and that is dangerous for even the hardiest of plants. You may be taking a risk, but you can give it a try. The size of the container determines how to prepare your yew for winter. If it's fairly small, insulate the pot with about a foot of foam or hay bales before winter sets in, and wrap the top in burlap to prevent the needles from drying out in winter winds. If the planter holds a cubic yard or more of soil you probably don't have to insulate it. Water the shrub well all through the fall and through winter if the soil doesn't freeze. For best results, I recommend finding a place to plant it in the ground before winter arrives. Hope this helps!