Why so tall?

screening

But from what? All I see is a road.

how will you shape something over 11 feet tall ..

understand that nothing stops growing at some magical height.. so everything will get tall ... it all about annual growth rate and the number of years ....

competition with other trees will reduce growth for those affected by such.. not only sun.. but root and water competition ...

how about you give us a few more pix.. of your house from the street.. and from your house.. across the street ... the purple lines really doesnt tell us anything...

what is your native soil.. and does it drain.. have you ever done a perc test..

what are the trees in the ditch?

ken

I would not plant a solid, 11 foot hedge of one plant. I'd plant a mix of plants and heights. I would place the taller trees to provide the privacy I expect you're looking for. For example, a taller tree in sight line with a window, lower shrubs out of sight lines.

Ken, not very concerned about shaping, and would think that is only once a year or so. If needed, I have ladders, but they make extension hedge trimmers on a pole, as well, which is more likely. The pink line is showing the location of the preferred hedge with relation to the trees whose canopy would overlap, but it is south facing, so I think it will receive notable sun for March-Sep, with the exception of a month or two. Unfortunately, I make a point to not share identifying information on the public internet, such as photos of the home, but it is fair to say the house is set back a ways and I'm looking to screen houses across the street, which are slightly downhill. The real question is about a plant that can fill the mentioned needs.

Native soil is 60% sand, 20% clay, 20% silt. Never done a perc test, but it drains readily and does not spread much. The trees in the ditch are some type of locusts... some have thorns, if that helps.

Thanks, Sigrid. I have many mature trees, and am not looking to plant more. I'm looking for a consistent barrier on one edge of the property. It doesn't need to be something aesthetic, per se, just natural. there are many other opportunities on the property for aesthetic landscaping, but this is just creating privacy for the whole property.

Your neighbors across the street would enjoy something aesthetic so please show them some level of consideration. Thanks.

I suspect you aren’t getting recommendations because most of us can’t speak to the unique challenges of the front range. This is a good place where you might be able to get specific suggestions. They are affiliated with CSU so should be evidence based. https://plantselect.org/

if budget is of no concern check this out:: https://www.instanthedge.com/

i agree.. NEVER plant a monoculture ... when one gets sick.. they all will.. and its usually the day after you say to yourself.. boy they finally filled in ...

i dont understand why you note a max height.. and then say you wont maintain them at said height... understand.. no plant stops growing at some magical height.. they just keep on going... that is why i asked about your specific number..

and also understand.. they will not grow uniformly.. as some will be in shade .... some with water competition.. etc ...

you seem to be attacking this as an engineer/designer and not a gardener ... and you are dismissing all the hardcore garden issues .. good luck with that ...

i can appreciate you not showing your address or some such.. but i cant help you design a garden solution with out seeing the garden ... its like saying you want help redesigning your bathroom.. but dont want to show us the throne....

i suspect the solution to your problems is not at the property line.. and could be solved more simply .. somewhere between the house and the road.... but you summarily rule that out... the closer a shrub is to the house.. the smaller it has to be.. as compared to putting it way out at the curb.. and hoping it will grow 10 or 15 feet tall in a decade or two ...

good luck

ken

I suggest Korean Lilac. If you trim it to shape each year it gets very dense and can provide a screen barrier even in winter. It is very easy to keep narrower if you need. It is considered a slow grower which may or may not suit you. Lessens the amount of sprawl and height you have to take off. These will fit better under your trees.

We have successfully used Moonglow Junipers as a dense hedge. To keep the narrow enough you have to trim off the horizontal branches and leave the vertical ones once per year. We had a tree trimmer show us how to select branches to keep the junipers narrower and it has worked will through the years. The ones we haven't tried to shape get ungainly large after 20 years but the ones we try to keep narrow seem to be working out. However those are 5-10 yrs growth behind the initial plants. Pretty much anything you buy will get bigger and taller than advertised. Most plants have a mature plant H and W listed on the tag. I think I read that that is the 10 yr size. So at 20 years they are generally much bigger. That has been my experience with most things we have put in.

For example we put in Moonglow junipers 20 yrs ago.

https://www.thetreefarm.com/juniper-moonglow

Says mature W is 10 ft and mature height is 20 ft. We spaced the bushes 10 ft apart and 5 ft off the fence. Many years ago they ran into each other and were over the 10 ft width. They need trimming off the fence each year and the taller parts we can't reach are probably at least 2-3 ft over the fence. In another area we put them behind a waterfall and near a gate we have consistently trimmed the horizontal branches that would block the gate or access to the back of the waterfall and these areas have stayed open. We have had to take one out for splitting at the base in a heavy snow and becoming a danger to the fence. We also have had to take some big branches off that have split near the base and sagged into the yard. But overall we have been delighted with how well they've done and a number of your neighbors have commented on what a nice screen it is and wish they had put something in like it. We did put in $20 small ones from Home Depot and they grew rapidly.

Pic. of Moonglow Junipers 10' apart, 5 ' off fence. No shaping or trimming. Probably 22-23 yrs old. Planted from $20 Home Depot gallon Moonglow Junipers.

Pic. of Same Junipers that have had branches trimmed due to splits from snow load.

Pic. of Moonglow Junipers, 6' apart. Being trimmed to keep them interfering with gate out of photo on left side. Maybe 17 yrs old. Planted from same 1 gallon $20 Home Depot Moonglow Junipers.

I have seen a number of nice hedges with regular lilac bushes. They grow pretty fast. I've also seen them pulled out for getting too big when they aren't give enough depth room since they start to crowd fences or sidewalk they were planted to close to. They do get dense enough to provide a privacy screen. This type of lilac will not be as dense and shape able as the Korean Lilac but it will gain height faster.