Do you need privacy year round, or really just in warmer weather? This question is important since it decides whether you are limited to just evergreen plants. You'll still hear cars with plants; only walls or earth berms will really block sound. If you plant some along the margin of your yard and some along the road, you shoud be able to achieve pretty good visual privacy. Regardless of what you plant, for the first year plan on mulching around the each plant a couple feet out as well as watering them any time you aren't getting regular rain during the growing season. Is it really 100% shade all day or is there some sun at the beginning or the end of the day? What side of your house faces north in the photo? The quality of the shade will effect how densely plants grow. The list below are plants that will grow in part shade or high shade, though not densely, in my experience. Check out clethra alnifolia, any of the shrubby dogwoods like the red-twigged dogwoods, or native viburnums (nannyberry, arrowwood, wild raisin, highbush cranberry), many of which may be available inexpensively from your local conservation service, though if not I've provided a link below to the NH state forest nursery which will ship orders in spring. These will be small and may do better if you grow them in a nursery bed or large pot for a year before planting them out. Many of the more common rhododendrons like R. roseum elegans, Olga Mezitt, and PJM can be bought from big box stores in spring and fall in quart or 2 quart pots, and if you are lucky quite inexpensively. I bought some Olga M and PJM a couple of years ago for $8 per pot and when planted 5 feet apart they will grow together. They may not bloom too well in that much shade, but they should grow and are evergreen. If you are willing to do some propagation yourself, old-fashioned forsythia grows pretty thick and twiggy enough to provide some privacy even in winter. They root and grow fairly easily from cuttings and then grow fairly quickly. If you peg down the lower branches of the rhodies, they will root and then can be transplanted in a year or two. Some needled evergreens may grow there. We have balsam fir growing in part shade in the woods, though I am not sure if you are too warm for it. White pine may grow for you there, though it won't stay at a height to block cars after about 20 years and won't be super thick growing in shade. Regardless, start working to get rid of the knotweed now, disposing of the seeds in a trash bag, not as compost. Either cut them down constantly or apply frequent coats of herbicide whenever you see leaves so that this doesn't get out of control. Here is a link that might be useful: NH State forest nursery

I had a large patch of it when I moved into this place. It grew to be about 8 feet high and took up a full 6x8 patch of my yard last summer. I noted where it all grew, and made my plans. I got out there first thing as soon as the snow melted this year and dug up all the roots I could get out, but it still sends up shoots here and there. As I find them, I take my shovel, and cut straight down about 3 inches away from the shoot, then wiggle (I have a straight edge square shovel about 6 inches wide, not much flex) but don't scoop the dirt out (you don't need to dig out the shoots, just the woody roots). That loosens the dirt around the shoot, then grasp the shoot at the very base (try to get it below the ground slightly if you have mulch or loose dirt) and WIGGLE it as you pull it, and you'll get the whole shoot, not just breaking it off at the ground. I've been told that if you keep pulling the shoots, after you've dug out all the woody root you can (THAT is the hard part!), you will slowly rob the plant of its strength, and it will eventually give up the fight and begone. Do NOT attempt to put ANY part of it in the compost pile! It's NOT just the roots that start new plants, it's ANY PART OF IT, so don't drop even a tiny shoot! You must BURN all of the knotweed plant and roots, as if you put it in the trash, it will then just takeover the landfill, and spread from there. If you have the concrete block to support it, you can leave the plants to completely DRY OUT, but there cannot be any soil contact of any kind, so it is just easier to burn it all. It's an extremely invasive species here in Vermont, it's a regestered Class B Noxious Weed, and its taking over like the kudzu did down in Tennessee. Every roadside is covered in it, it has killed out almost all of our traditional roadside flora like ferns, milkweed, grasses, wildflowers. It's all dead, it's just knotweed, everywhere. Southern Vermont is basically infested beyond all hope at this point. Here's a good webpage on eradication methods: http://efotg.sc.egov.usda.gov/references/public/VT/JS315-knotweed.pdf For a good note: I made the effort to talk to my neighbors about what it is and how invasive it is, and EVERY ONE OF THEM let me dig it out of their yards too. So, don't be afraid to talk to your neighbors about it, there's a good chance they will be smart enough to let you eradicate it from THEIR yards too! Here is a link that might be useful: Vermont Agency of Agriculture: Noxious Weeds

Hi - we managed to get rid of knotweed completely - will tell you how I did it. I'm here because of a BBC article and got me remembering and thinking. I don't understand why everyone says this is so difficult to get rid of it seemed really easy to me anyway. 4 years ago we bought a flat - it had knotweed noted on the survey, it was pretty big area of huge tall weeds, but we haggled the price and bought for cash. Told we wouldn't get a mortgage because of the knotweed. Neighbours told us it was a nightmare they had battled for years and told us all the stories of council officials coming out to look at it and trying to apply for grant funding etc etc to get it dug out with JCB's and burned. Anyway, we decided ourselves to get an estimate from a professional company - priced in the £000's. I did some reading and research about the plant and controlling it. Went to b and q and bought a large quantity of the strongest glyphosate I could find, it said it could treat like 500m/sq. this patch was maybe 20 metres by 5 metres - pretty big for me anyway. It was supposed to be pretty diluted but I only used about 10% water maybe. I also bought a £15 manual spray pump and some gloves and some sponges. I went with some ladders on a Saturday morning in August, it was about 15 degrees C, cloud cover and dry. i coated every single leaf I could with the stuff - several times during the day and again after it dried off or was absorbed. I then found all the thickest stems and bunches and cut them down about halfway, and poured the stuff into the stems - filled right to the top. Then topped them off later that evening - and used the last of the strong spray solution I had made for another final spray coating. Over the next few weeks they starting visibly dying. The winter came and went and by July the following year everything was completely dead. I took plenty of before, during and after photos which I still have. That was 4 years ago I did that and not one single sign of it has returned. It cost me like £80 of materials and maybe 12 hours of my time. I knew nothing whatsoever about Japanese knotweed or plants and gardening and still don't. I was later told that national rail and the local council had actually sent 'a man' every season for 'several years' previous to our buying the place to 'spray the plants' to try and get rid of them. With little success apparently. What I find totally and utterly bizarre is that someone like me, completely clueless about horticulture and plants, was able to completely kill - permanently - a pretty substantial bank of this stuff in like 1 day, with stuff bought from the local hardware shop - and yet the Internet is full of stories and news reports of people spending fortunes and despairing in heartache over it. Was I lucky somehow? Genuinely I've always been curious about this and would welcome input from those more experienced.

Thank you. I used eraser [glyphosate] on weeds a couple of growing seasons and it worked well. Believe it or not, the next 2 yrs I had about a 5-10% germination rate. The glyphosate actually sterilized the soil. I didn't figure it out until a year later. What I have done [over the last 4-5 months] is piled-up cut branches from live oaks, cedar and other up to 2-3ft tall throughout the garden. All of the old weed stalks and other are still there too. I plan on burning the entire plot of branches, hoping to disintegrate the last years [2016] surface seeds and everything else as well. The potash remains should be good for the soil. Once I've done this, I'm going to till it and see if I can get the next rd of seeds up and going before any site of seeds. I'm going to repeat this process until the germination rate is null to little enough that I can easily deal w mechanical removal. If there is anything else you guys can suggest, I'm open to ideas. I think I will have to forego this years spring/summer planting to do it right. I would have burned the branches already, but every time I've been out there it's either recently rained [which I will never complain] or the winds have been too strong. The rest of the areas are green, but I just do not want to take the chance. Again, thank you very much for your suggestions. I'll post back on the results. PS - as far as weed types, goat weed and a grass like weed that puts out seed pods like Bermuda grass and branches out runners too. I looked at a weed ID chart and could not find it