Just my thought, but forsythia's growth habit does not take pruning that well and when not in flower is pretty boring. Burning bush is an OK choice, but I would recommend another plant to partner with it. Maybe a viburnum of some kind or a lilac like Miss Kim.

My thought would be whats it going to look like in the summer and winter. Maybe an evergreen & Burning bush would be better. Maybe something with summer and winter color (variegated red twig dogwood or a smokebush).

Just my opinion, I may be wrong.

Jim

My own strong opinion:

I can't think of two worse choices - other than they don't die particularly easily. Forsythia is pretty much a two week species in spring, and spectacularly unassuming the rest of the year. Burning bush is bright in fall color, but quite the bore otherwise AND a tremendously invasive species in the northeast.

You could select from among so many other species that would provide you so many other seasons of interest - from flowering, foliage, form, fall color, fruit - and none of which need be such non-performers as the two you've listed.

List more of your requirements - length of hedge, sun exposure, soils, moisture conditions, minimum/maximum height, etc. From this information, contributors here can propose so much more of value, interest, and reward for your future landscape pleasure.

highly invasive in pa.. see link

but i agree with VV ... you can do so much better..

and then i note you said: create a 'long' hedge line

let me tell you something.. when i moved here .... i was 40 ... and gung ho on all kinds of ideas ...and lo and behold 10 years later.. i am wondering why i planted all these things that need ANNUAL MAINTENANCE PRUNING ...

you are creating a potential nightmare ... unless you define a long row as 3 plants.. lol ...

try to figure out.. what you can plant.. that will not require .. once or twice a year pruning .. FOR THE REST OF YOUR LIFE..

trust me.. what seems like a cute idea now.. can really end up a problem ...

hedge rows are soil conservation.. by definition.. see if PA has soil conservation districts.. and find out what they recommend for your area ... mine even offer small plants for sale at spring planting time.. cheap ...

ken

Here is a link that might be useful: link