You don't say where you are but Plants of the Southwest has seed for Giant Sacaton which is a drought hardy desert type of grass native to the SW but will grow elsewhere. I grew several from seed a few years ago, they came up easy. Its a large very ornamental grass, takes 2 years to reach substantial size. By year 3 they are mature. It puts up blooms in early summer that look fantastic lit by sun.

Another really big one is Ravenna Grass, you can find seed online. There is one next door and if they don't trim it in early winter I end up pulling seedlings. Its pretty fast growing and gets big.

For a screen you do need a big grass. The panicums (Switch Grass) are nice and upright but wouldn't block a view. There are several cultivars. Another is Big Muhly aka Muhlenbergia lindheimerii.

A nice combination is Switchgrass with Little Bluestem planted in front. I've seen that around here and its stunning (if its full sun and not overly rich soil).

Check out Santa Rosa Gardens. They sell 4" pots and have great sales on ornamental grasses in late spring and late fall. You might solve your $$ and view problem that way. Markdowns are as low as $3.99 or even $2.99 on whatever they have left over. These people are very reliable and safe to order from. I've ordered several grasses from them for years.

You could work on the border in stages, that is what I am doing. With grasses except for a few exceptions, you nearly always end up with plenty of volunteers and can use them to create a swath of grass for free and maybe even add in some native flowering plants for a nice natural look.

As a privacy screen, grass is a good idea but you do have to cut them down in late winter before new growth starts so there is always a down time as far as a screen is concerned and the labor. Other than that they are maintenance free.

Look around your area for examples of grasses that would achieve what you're hoping, and then ask to take a volunteer or a small division. Most grasses grow and spread so vigorously that owners find it hard to contain them! I left a note in someone's mailbox and got message to please help myself. It's a good way to see what you're getting, avoid the risk and trouble of sowing from seed, and meet a neighbor..

I'm in zone 7. What about giant reed grass? I think we have a lot of this along the river we live along. Would it be ok to either dig some of them up and replant, or take some seeds direct sow? There isn't much info about sowing these on the internet... Would i be in trouble if i tried that and it worked? As in, would it get out of control? Or be too invasive?

Also, how long would it take the small 3.5" pots to get to about 4'? Thanks!

Arundo Donax, giant Reed is a TERRIBLE INVASIVE. Please don't plant that one. Especially if you are by a river. It can alter the hydrology of a river. IT is terrible to control. All the control methods seem to do is make the plant "Angry". We have been fighting it on the Blanco river especially since the flood. I hear some horror stories about this down here. On the rio grande, it has become a draw for drug smugglers to hide out in. Complete with gun battles with police and disappearing smugglers. Stuff is thick. and gets to cover several acres when happy.

"Giant reed (Arundo donax) invades riparian areas, altering the hydrology, nutrient cycling and fire regime and displacing native species. Long ‘lag times’ between introduction and development of negative impacts are documented in some invasive species; the development of giant reed as a serious problem in California may have taken more than 400 years. The opportunity to control this weed before it becomes a problem should be taken as once established it becomes difficult to control."- It has taken a lot less that 400 years in Texas.

I discovered that the 4" pots establish much faster than gallon plants. Gallon sized or larger grass plants are nearly always root bound, often they are extremely root bound with a mass of roots girdling around the pot forming an impenetrable block of tight roots. You plant them, they just sit there (sometimes they never root in at all after an entire season and simply decline) while the 4" plugs establish themselves right away and quickly become gallon sized plants often outgrowing the more expensive gallon sized plants.

Beware of gallon sized grasses on the clearance racks. Check the roots. I got burnt one year and lost all the 'sale' plants I purchased due to root bound plants.

Sowing seeds is obviously slower, sometimes you'll need an entire season just to get up to the 4" pot size. Different grasses have different growing rates. Example: Sideoats grama is a fast grower than Switch grass. Sideoats grama is a very pretty grass by the way that is good on slopes and has a bloom time from early summer into late fall. Stunning grass, about 3 ft tall, looks great in a mass planting.

Most 4" pots will bloom by the end of the first season if planted in spring, will be good sized specimens the 2nd season and are fully mature by the 3rd season.

I agree 100% with wantanamara about the invasiveness of Arundo Donax. Besides all that, its overwhelmingly huge and rather ugly after several years. Remember all that last years dead growth has to either be removed or left to look dead & ratty and will keep building up year after year unless someone cuts it back with what---a machete maybe? How anyone would want the chore of cleaning out a large swath of Arundo each year is beyond this GW member. I always imagine most people who have it regret they planted it judging by how it looks and overtakes areas.

I'm not giving advice, just giving my experience with Pampas grass. At a previous house I too wanted a barrier and bought a bunch of baby Pampas grasses. For the first couple years, it was wonderful, they grew quickly, had those ornamental plumes, looked good. Then the middle of the clump started dying and they began to look ratty. By then they were each about 5 or 6 feet in diameter. I decided to just take all of them out, and removal (by me) was a nightmare.

Seems like 98% of them are eyesore 'doughnuts' around here because most people either don't care, don't understand whats happened or its just too daunting to think of dividing a mature clump of Pampas grass. I really detest Pampas Grass but people seem to get smitten, all they see are those fluffy plumes but its just a future headache ---a nightmare doughnut in the making.