Hello Jan,

Grasses or other container plantings as a screen is a great idea, and should be fine to try. How large of a container to use will depend on several factors, including the plant species chosen, though most hardy perennials (grasses included) will need a minimum of a 12" wide pot. Larger not only allows for more root growth (which in turn will support a fuller top), but also insulates the root ball from temperature swings in winter, which can be the main factor behind plant losses in containers. Other considerations regarding pot size include:

• preferred container material (plastic tends to be the most crack-resistant from freezes, but some ceramics are frost-tolerant)
  • plastic and resin types are lighter and easier to move around as needed, but may be prone to blowing over in high winds
  • ceramic (avoid plain terra cotta if you can, as it's too crack-prone) being heavier will help stabilize the plants in wind but can be a bear to move around without the help of wheeled trays (sometimes called plant dollies)
• make sure your container of choice has drainage holes (at least one, but several is ideal) and do not block them with pot shards or other obstructions when filling them with potting mix; some containers may not come pre-drilled, but instead may have drillable "guide" holes if you have your own tools
• wider pots will allow you to include one or two other plants if you wish, like decorative flowering native perennials if you wanted to attract pollinators or simply enjoy seasonal blooms

We don't have a specific depth recommendation since pot width usually determines pot depth to a certain extent, based on commonly-used pottery designs, though there are uncommonly squat or tall designs available. Most pots have a design ratio of similar widths to depth, which is just fine. Deeper proportions can allow for better drainage if that's a concern, but in either case, use potting mix as the only filler (as opposed to packing peanuts, gravel, or other space-filling materials sometimes suggested) as they not only can surprisingly impede drainage, but also deprive roots of that much more growing space and nutrient access.

Which plants will work best as your screen depends on the summer light levels. "Full sun" is considered about 6-8 hours or more of direct light, especially during the strong late morning, midday, and early-afternoon hours. Most grasses that attain any height suitable for screening need full sun to thrive and may flop or grow more sparsely in increasing levels of shade. You do have grass choices for part shade, but they will be species that mature much shorter. There are also many native perennials that could work (either in place of grasses or alongside them), but they are too numerous to list here without more parameters to narrowing-down the list.

As a general rule, try to only consider plants whose winter hardiness rating is at least one (ideally two) zone colder than needed for in-ground plants. For instance, most of central MD is solidly in zone 7, so plants tolerating zone 6 or even 5 should have enough cold-hardiness to be less likely to sustain damage to their roots during the winter. (This is due to their greater exposure to temperature changes by being above-ground in a pot. In-ground roots are much more insulated.)

Within grasses for full sun or a mostly-sunny exposure, your ideas of Schizachyrium scoparium and Sorghastrum nutans are good options. Other natives with good height include Andropogon virginicus and Panicum virgatum.

Miri

You're welcome!