Question
I purchased 2 5 gal Forsythia bushes at the local hardware at 1/2 price & plan to plant them in a Northern exposure against a garage wall with some Hostas.  How/when do I plant them? It's in the 90's now and will get below freezing this winter here on the Northeastern Plains of Colorado.

Answer
Hey, June.

Forsythias grow best in very well-drained soil and in full sun, so I think planting them in a northern exposure against a garage wall with hostas is the wrong thing to do, especially since forsythias can grow up to 10 feet tall and 6 feet wide. Of course, you could always prune them, but I think the more important thing in order to get the best effect from them is the full sun exposure, which they just aren't going to have enough of if they are planted on the north side in a state such as Colorado.

I can't tell if you already have the hostas there or if you are planning on planting them at the same time as the forsythia. If the hostas already are there and are thriving, then it's probably the wrong place for forsythias. If you haven't planted them yet, then I think the forsythia/hosta mixture is wrong, although you could possibly plant the hostas under the forsythias in a southern exposure. That would give the forsythias the sun that they want, and they should provide filtered sun for the hostas. Hostas are very adaptable (I've grown some here that did very well under pine trees), but they'll do best in that northern exposure.

You got the forsythias at half price because they are out of season and now is really not the best time to transplant them. It can be done as long as you give them what they like best, i.e., sun and good drainage. Don't just transplant them and ignore them; look after them daily to detect problems.

They are deciduous and hardy through Zone 5, which northeastern Colorado is in, so they should be able to take both the high and low temperatures that you get there.

Whenever I need good drainage, I'll use a mixture of cactus soil (two thirds) and any type of regular potting soil (one third) and dig a hole 2-3 times larger and deeper than the container the plant came in.