looking for a site to find out when best to plant a tree?

Question

lumbar poplar tree in particular

Answer 1

You can plant any time that the tree is available in your local nursery, or whenever the mail order place ships them to you.

Here's a site to tell you about your Lombardy Poplar
http://landscaping.about.com/od/landscapedesignprivacy/p/lombardy_poplar.htm

Answer 2

If you are sure you want this tree I'm glad to help. This is an amazingly strong and shaped plant. Keep in mind that it is strictly an upright growth tree. Fifteen years from now it will be some twenty foot high but only three or four foot in width by leaf drip-line. Most times these are planted in a group and majestic in stature during the summer and fall.
Provided you make the proper base (hole twice the depth and twice the width of the root ball) and back fill the hole with a combination of Sphagnum Moss, Gypsum, and a basic fert (10-10-10 with minerals), mixing soil removed with the ingreds., you can plant this puppy any time. It does need water to begin but needs nothing but rain thereafter.
Since you are probably going to a nursery for such a specimen tree ask them about the auto-watering bags they have. You stake the tree and wrap this device around the base of the unit. It can hold from 25 to 50 gallons of water. It drips the water so you don't have to do anything but fill it every couple of weeks.
I forgot to mention that when back-filling the hole it would be appropriate to add a water retention agent such as GelScape. In the years to come this will keep the roots supplied with water through rough times. Great Choice and Good Luck!

Answer 3

Right now, get it in! Check for the major root flares though. You want them at or near surface level.

Answer 4

try hgtv.com. there should be a zone map there and that will give you the right time of year for your area. or just call your local nursery.