The Screening Test

Foundation planting at Hayefield with Helianthus 'Lemon Queen' and Vernonia

Text and photos ©Nancy J. Ondra

One of the biggest challenges of creating a new garden on a relatively flat, featureless field has been figuring out how to break up the view a bit. Partly, I wanted to create some privacy from the roads that border two sides of my lot. I also wanted to add some screening within the garden, so the whole thing wasn’t visible from one spot, and to create some sheltered sitting areas as well. I needed to find a way to screen the area under the raised porch, too, so the junk-storage space underneath wasn’t visible.

My previous garden was very small, so it wasn’t a big deal to invest in some special trellises and screens, or to have Mom build them. This place is so much larger, though, that even buying enough lumber for Mom-made structures really isn’t an option. Sizeable shrubs and trees are pretty much out of the budget too. So I’ve turned to another option: perennials that are eye-high or taller.

It’s fairly easy to find tall perennials simply by skimming catalog descriptions or checking plant tags. Over time, though, I’ve come to realize that there are specific qualities that make some perennials much better for screening than others of the same height.

Quick Growth. Tall perennials as a group require some patience for screening purposes. It often takes three to four years after planting – and sometimes even a few years longer – for them to reach their mature size: a little faster, maybe, than many shrubs, but still a fair wait unless you start with sizeable divisions and not small potted plants.

Unlike most shrubs, perennials also have a seasonal down-time. Even if you wait until early spring to do your garden cleanup, you lose all perennial screening from the time you cut the stems down until summer, at least. I don’t consider the lack of spring screening a big problem, because I’m so busy planting and weeding that I mostly can ignore cars and people going by.

Eupatorium maculatus 'Carin', Amsonia hubrichtii, Sedum 'Purple Emperor', and Rosa glauca

Around the end of June, though, I start spending more time puttering, strolling, or sitting, so I appreciate a bit more privacy. That’s rather early to expect good screening from most tall perennials, but there are a few that I’ve found reach a respectable height (about 4 feet, or taller) by mid-June. The Joe-Pye weeds (Eupatoriadelphus [Eupatorium]) are typically pretty quick to fill in, especially the giant, dark-stemmed ‘Carin’ (above), which is easily 4 feet by early summer and 6 feet by midsummer.

Persicaria polymorpha

Above is giant fleeceflower (Persicaria polymorpha) with its new plumes poking into the 4-foot range by the middle of June. It generally reaches its full height of about 6 feet for me in early to mid-July.

Below is one of my most favorite all-around perennials: feather reed grass (Calamagrostis x acutiflora ‘Stricta’). This picture is from August, but it’s essentially the same full height of about 5 feet at flowering time in mid- to late June: a little low for privacy but lovely for lightly screening sitting areas.

Calamagrostis x acutiflora 'Karl Foerster'

Dense Habit. The density of a perennial from bottom to top also affects how useful it is as a screen. As you can see in the above photo, feather reed grass isn’t all that dense, but I like the relatively uniform look. This strip is only about 1 foot wide; a wider swath gives more screening.

In this same area, I have several other perennials that haven’t worked out at all for screening, even though they get taller than the grass. One is white-flowered Japanese burnet (Sanguisorba tenuifolia ‘Alba’), shown below in mid-August. Though it easily reaches 6 feet or more, the foliage stays close to the ground, and the tops are totally see-through. I adore this plant in both foliage and flower; it’s just not a good choice for screening, in my opinion.

Sanguisorba tenuifolia 'Alba'

Another tall perennial that’s a beauty for foliage and flowers but a dud in the screening department is giant coneflower (Rudbeckia maxima). The bottom foot or two are pretty dense, but above that, it’s see-through in bloom and in seed, as shown below in mid-August.

Rudbeckia maxima

Now, look behind the coneflower, and you’ll see a perennial that’s fantastic for screening: ‘Morning Light’ maiden grass (Miscanthus). Even with a spring root-pruning, these three clumps, roughly 18 inches apart on center, have formed a dense visual barrier to about 6 feet tall by mid-August.

Right across the path from that combo is another great screening perennial: frost grass (Spodiopogon sibiricus). It holds its leaf blades at a wide angle from the stem, so they’re more horizontal than vertical, creating a solid mass of foliage up to about 4 feet, and the relatively airy but numerous flower plumes add another foot or so by mid-August. This beauty holds up well through the fall, too.

Spodiopogon sibiricus Spodiopogon sibiricus
Spodiopogon sibiricus in late August Spodiopogon sibiricus in mid-October

White snakeroot (Ageratina aromatica [Eupatorium aromaticum]) has also proven to be a good option for dense screening from crown to tip. It’s shown below in full bloom at about 6 feet tall in mid-September of 2005. (On the down side, this plant is also a prolific self-sower.)

Ageratina aromatica [Eupatorium aromaticum]

Sturdiness. Ah, now we come to one of the big challenges of growing tall perennials: keeping them upright. It’s no good having a perennial that grows quickly and makes a nice, dense summer screen if it’s going to flop everywhere by the end of the season. That snakeroot above, for instance, is one that can readily split or sprawl if it’s in a windy spot.

My property is wide open to winds, and there isn’t much I can do about that, but the fact that I rarely fertilize or water does help to encourage stronger (though somewhat shorter) stems. As far as I’m concerned, staking isn’t an option: If you’re going to have to stake perennials to keep them upright for a screen, you may as well put up a permanent screen or trellis and be done with the job once. Pruning (by cutting the plants back by half or so in early summer) isn’t very practical, either: the resulting plants will be denser, for sure, but they’ll also be shorter, and maybe too short to be a good screen.

The Joe-Pye weeds are usually quite dependable for staying upright without help here. Shown below are a few hybrids that seeded themselves along this fence. (I started out with selections of Eupatoriadelphus purpureus, E. maculatus, and E. dubius, but they’ve crossed so many times now I have no idea what these might be.)

Eupatoriadelphus with Lilium 'Black Beauty'

I have the same situation with the various ironweeds (Vernonia) I started out with: no clue what the seedlings might be, but they’re all delightfully tall (anywhere from 5 to 8 feet for most) and reliably upright.

Vernonia

Most grasses, too, are good about staying upright for me, but one is truly exceptional: ‘Northwind’ switch grass (Panicum virgatum). I used to think ‘Heavy Metal’ was the best for this habit, but it’s shorter (usually 4 to 5 feet), and after a few years, it formed a wider clump that wasn’t so obviously narrowly upright. ‘Northwind’ has produced bolt-upright, 6- to 7-foot-tall shocks for going on six years now without division, and the clumps stay that way even through winter snow and ice until I cut them to the ground in March. It’s shown below in mid-July.

Panicum virgatum 'Northwind' with Rudbeckia maxima

Durability. Even if a tall perennial has sturdy stems, it’s not much good if it starts to decline soon after flowering, if it’s prone to pest problems, or if it has to be cut back after bloom to keep it from seeding all over the place.

I love Culver’s roots (Veronicastum) for their summer height and spiky blooms, for instance, but mine tend to start dropping their leaves in late summer and are pretty much leafless by fall: nice for form but useless for screening. If the summer has been dry (pretty common around here), my Joe-Pye weeds tend to do the same thing starting a few weeks later, so their stems are pretty much bare by mid- to late September.

Here again, the warm-season grasses shine, because they just keep getting better through the late-summer through fall season. Indian grass (Sorghastrum nutans) is one that’s not a great summer screen, because its foliage mostly stays in the 3- to 4-foot range. But in August, it produces its upright flowering stems, and they make a pretty light screen. (As with the feather reed grass, planting the clumps in a wider row would produce a thicker screen.) Shown below is the selection ‘Sioux Blue’ in mid-August.

Sorghastrum nutans 'Sioux Blue' with Schizachyrium scoparium and Rudbeckia maxima

Dog fennel (Eupatorium capillifolium) is another incredibly sturdy “perennial” that performed admirably as a screening plant. I put perennial in quotes because dog fennel tends to perform like an annual for me, even though it’s apparently supposed to be hardy much farther north than Pennsylvania.

Maybe I should consider myself lucky: I’ve read that it can be both aggressive and invasive in mild climates. But oh, those strongly upright shoots and feathery, bright green leaves sure were pretty. I ended up trimming out their tips when they reached the front-porch railing (about 7 feet tall), so they bushed out some more than they usually would, and they looked neat well into winter. One clump is shown below in late November, behind an edging of ‘Oehme’ palm sedge (Carex muskingumensis).

Eupatorium capillifolium and Carex muskingumensis 'Oehme'

The Best of the Best. If I had to choose just one genus of perennials for screening, it would have to be the switch grasses (Panicum). I’ve already mentioned a few selections of P. virgatum – ‘Heavy Metal’ and ‘Northwind’ – but there are lots of others I like. One particular favorite is ‘Cloud Nine’, with its V-shaped habit and 7-foot height. The airy tops catch the slightest breeze, so they are almost constantly swaying and rustling. You can just see the pinkish tops of it at the end of the path shown below.

Arc borders at Hayefield

Below is ‘Cloud Nine’ about a month later (in October), towering above ‘Cassian’ fountain grass (Pennisetum alopecuroides).

Panicum virgatum 'Cloud Nine' with Pennisetum alopecuroides 'Cassian' and Spodiopogon sibiricus

An even-more-favorite favorite of mine is ‘Dallas Blues’, because its powder blue, wider-than-usual leaf blades and pink flower plumes are so distinctive.

Panicum virgatum 'Dallas Blues'

I have a corner of the front garden planted with a half-dozen of these to create an almost-secret sitting area. Even though I’m only about 30 feet from the road there, the density, movement, and swishing sound of the plants as they move in the wind block a good deal of the noise from passers-by. It grows fast, it’s sturdy, it’s durable, and it’s dependable: exactly what I’m looking for in a screening perennial.

Panicum virgatum 'Dallas Blues' Panicum virgatum 'Dallas Blues'
Panicum virgatum ‘Dallas Blues’ in late August Panicum virgatum ‘Dallas Blues’ in late October

20 responses to this post.

  1. Your garden is so fascinating, Nan, I would love to see it some day. Your use of grasses is very inspiring too. I have a very blue panicum called ‘Prairie Blue Sky’, but it has lax stems, still beautiful though. Northwind looks like a winner, I will have to be on the lookout for it, after buying Heavy Metal after reading your glowing report. I love the tall perennials too, even when you don’t need screening. We have a very tall sunflower that is planted around the hydrangeas to give shade until the tree grow a little more, rudbeckia lanciniata, it sounds like one you could use also. I could look at photos of your garden all day.

    You made me panic there for a minute, Frances: I acquired ‘Cloud Nine’ and ‘Prairie Sky’ at the same time, and for several years, I could never keep the names straight, so I just now double-checked to make sure I used the right ones here. ‘Prairie Sky’ was significantly shorter and so sprawly for me that I ended up moving it to the meadow; you’re right that it was a beautiful blue, though. I can overlook that small lack in ‘Cloud Nine’ when it has so many other great qualities. I still like ‘Heavy Metal’ very much for both habit and color, but ‘Northwind’ is in a class by itself on habit alone. (Its foliage color is distinctly more green than that of ‘HM’.)

    Great point about using tall perennials to create some shade for lower companions, too. We have Rudbeckia laciniata at work, and it certainly qualifies for screening in the height department (easily 7 feet), but I’ve had a hard time keeping it from sprawling, even with some experimental midsummer pruning. Could be because the soil’s more fertile and more frequently watered there. I think a test here at Hayefield is in order!
    -Nan

  2. Nan – I’m still so envious of your ornamental grasses! They are just spectacular. I’d love to know what would be on your grass list if you lived in my Zone 5.

    Have you tried any of the switch grasses, Gina? As far as I know, they should be hardy into Zone 4, so if I were in Zone 5, they’d still be tops on my list. Except for ‘Prairie Sky’, they’ve all been winners for me for ease of care, fall color, and winter structure.
    -Nan

  3. The grasses, Eupatoriums and Vernonias do so well here, I’m thinking that I’m just going to keep going with more of the same.

    The Sanguisorba (and some of the others you mention) may be thin. But if you plant them inside the screen, they make you focus closer, increasing the effectiveness of the screen. Your eye doesn’t reach the screen, much less beyond.

    Hey, that’s an excellent point, Craig. When I was writing this, I was thinking mostly of single-species or -cultivar screens, but you’re right: mixing several different tall perennials lets you take advantage of the best traits of each. You’ve given me a new way to look at the photos of the plants I said weren’t that great for screens. Thanks!
    -Nan

  4. That dog fennel is pretty cool, but you know what, so is your whole garden. If I’m ever in eastern PA, I’m stopping by (unannounced, of course). Do you cut your ‘Lemon Queen’ back in early summer? Mine has become so huge and gangly this first year (6′ tall, at least 4-5′ wide and crowding out some eupatorium ‘Prairie Jewel’). I like Craig’s point, and might try that with my sanguisorba.

    Oh, surely you’d at least send me an e-mail warning first, right? Otherwise, you’d be disappointed with the real untidied thing. (At this point, after nearly a month of no rain, I’m not sure even tidying can help it.) Yes, I do cut all my ‘Lemon Queen’ back by half around June 1. That used to be enough, but now it doesn’t even notice, so I often half it again around July 1.
    -Nan

  5. Thanks for the tour of the tall screening perennials. And for a tour of your beautiful garden. I have a question about the Sanguisorba tenuifolia ‘Alba’. Where did you get it? I haven’t been able to find it in any mail order nurseries, much less local nurseries.

    I grew it from seed a number of years ago (can’t remember the original source), and it has sown itself around since then. I could try collecting some seed if you’re interested, though it’s starting to cross with some of my others now, so I’m not sure it’ll come true. Or, you could contact Digging Dog Nursery to see if they have this one available now.
    -Nan

  6. I like your use of taller plants. Tall plants look good in my garden.

    As I get older, I find yet another reason for liking in-your-face plants: You don’t have to lean over or kneel down to admire them!
    -Nan

  7. Some great ideas! Those ornamental grasses look great, especially the panicums. ‘Cloud Nine’ will be going on my list. I like the way you placed the Feather reed grass in front of the rail fence.

    Thanks, Dave. With its strongly upright habit, that feather reed grass is ideal for filling narrow spaces.
    -Nan

  8. Posted by ourfriendben on August 25, 2008 at 10:38 am

    Another fantastic post, Nan! But you somehow left out my very favorite screening plant, pokeweed, gorgeous in three seasons and requiring minimal maintenance (just cutting the dead stems off in winter or spring and removing any seedlings that you don’t want). Btw, the variegated pokeweed you gave me is thriving. Waiting with bated breath to see what happens next spring! I love Baptisia australis for screening, too—it’s huge, handsome, and remains upright for me. Thanks for the other great suggestions!

    Good suggestions, OFB. I guess I left pokeweed out for two reasons: one, because of the self-sowing and two, because (for me at least) the plants are mostly top-branching, so they’re not as evenly dense as I’d like for screening. But you know that neither reason stops me from enjoying pokeweeds in my borders!
    -Nan

  9. I’ve never been a fan of ornamental grasses but you may have converted me here. I love that Cloud Nine. All I can say is WOW!

    Do give some grasses a try, Jane Marie – you’re in for a real treat! The tallest ones take a few years to reach their full glory, but they’re definitely worth waiting for.
    -Nan

  10. Great post and luscious photos, Nan. I felt like I was reading another of your books. I’m in love with your fall grasses especially.

    By the way, I’m wondering whether your garden is deer-proof (i.e., fenced). If not, are deer a problem for you?

    I sure do have deer, Pam, both inside and outside of the fenced part of the garden. (They can pop over the 5-foot fence like it’s not even there.) And that gives me yet another reason to love ornamental grasses: So far, at least, the deer don’t touch them.
    -Nan

  11. Superlative post Nan. As a fellow lover of outsize plants–though my tastes run somewhat more to comparativley ephemeral annuals and tropicals–I appreciate how you’ve made use of them in such striking combinations. Your eye for texture rocks. Surprised not to see Miscanthus giganteus aka M.floridulus, at about 10 feet it makes a superb hedge or backdrop, and excels at creating sense of enclosure.

    A question: I’ve been looking for that Eupatorium capillifolium without success. Where’d you find it? Also, love that dark-stemmed Joe Pye weed.

    Thanks, Steve. I guess I’ve not tried Miscanthus giganteus because it’s a little *too* big to be in scale with most of my other tall things (mostly in the 6- to 8-foot range). Maybe I should consider it, though.

    I wish I could give you a source for the dog fennel, because I’d love to try it again myself. I picked it up at a local greenhouse several years ago, and I’d swear that it had a Proven Winners label. Unfortunately, all five of the clumps died over winter, I haven’t seen plants or seed for sale since, and didn’t get any self-sown seedlings.
    -Nan

  12. Posted by lisa at greenbow on August 26, 2008 at 4:36 pm

    Every time I see pictures of your tall grasses I start looking around my garden wondering where I can plant some. Then I think about how you use a brush hog to take them down in the spring. UGH… I think I will just admire them from afar. However that blue grass color is almost more than I can resist.

    To be fair, I use the brush mower only on my big perennial-and-grass plantings. In my mixed borders and small areas, it takes just a few minutes to cut each clump to the ground with pruning shears. It’s a more-than-fair exchange for such a long season of beauty. So, don’t let that stop you from planting some, Lisa!
    -Nan

  13. You never disappoint! So many wonderful photos to illustrate your choices! I love that ‘Cloud Nine’. Maybe the fish pond screening should be just perennials…er, I am pondering a fish pond screening garden. Great options here.

    Whew – you lost me there for a second with the “fish pond” reference, Layanee. But definitely do consider the perennials for screening!
    -Nan

  14. Nan, I haven’t actually taken time to read this post yet, so I’ll be back to do that later. Just wanted to pop in and tell you that my Gardening How-to mag came today, and my astute hubby saw the front cover and recognized your gorgeous garden! Wow!!! Congratulations! He was so pleased with himself :) Your garden looks wonderful.
    How about you..first the NY Times and now the front cover of a gardening magazine. Very impressive! Is the first photo in the article also your garden? It looks like it to us.
    I enjoyed that NY Times article, BTW, and was pleased to see you pictured there with “the boys” :)
    I need to catch up with your posts here. Summer is just too busy for blogging! The corn crop is fabulous this year. We just spent the morning freezing 23 qts (plus 14 last Monday), and have been able to keep neighbors, family and church friends supplied. Several have frozen some. There’s even enough for the coons this year :)
    Now, I must get out and do some gardening before all this beautiful sunshine goes away….(we had 50º this morning..brrr).

    Hi Kerri! Holy cow, your husband really is sharp to be able to tell it was my garden. I don’t get the magazine, so I haven’t seen it, and I don’t know if there are other photos from here. When other photographers shoot here, I don’t normally get told when and where they sell the images. I think Rob did ask me about this one, though.

    (Wow, I just found it on-line, and I don’t think I’d have recognized it myself, because the image is reversed!)

    I know what you mean about keeping up with blogging. It seems it’s all I can do to handle posting and responding to comments here and at Gardening Gone Wild, for now, anyway. I do hope to catch up with reading others once things slow down outdoors.

    Glad to hear you had a great corn crop this year. Sound like you’ll be enjoying it often this winter!
    -Nan

  15. I think I’ll have to find a home for Panicum ‘Cloud Nine.” The problem for me is that I most need screening in shaded areas, but my soil is too dry to support the tall perennials. Right now my best screening perennial is Aster tartaricus. Those huge leaves block out everything & the plants end up over my head. (I’ve also gotten behind on blog reading & commenting. I’m hoping to have more time now that school has started.)

    Hey, that aster is another excellent suggestion. I’m working on getting it established here, but it’s only about 3 feet tall at this point, thanks to the drought.
    -Nan

  16. I hope you keep this blog page on the site for a while. All this information is invaluable to me for when we get our garage addition done. I plan on a large patch at the end of the drive to plant perennials (perfect sunny spot and the plants won’t interfere with snow removal). Dramatic screening from the back yard would be perfect! Thank you so much for sharing your personal experiences and photos!
    -D

    Thanks for visiting and commenting, D! The post will always be here, but it won’t always be at the top. You can look in the archived posts section to find it later. Good luck with your project!
    -Nan

  17. What a wonderful post. Your garden is very inspiring. I too want to look up the “Cloud Nine” grass. Is the “Dallas Blues” that you mentioned shown in the photo?

    Thanks, Phillip. The ‘Dallas Blues’ is shown in the summer-and-fall comparison near the end of the post, enclosing the Adirondack chair. That doesn’t really do it justice, though. I’ll have to see if I have some better images.
    -Nan

  18. Thank you for such an excellent and timely post! I’ve been wracking my brains trying to find a decent and relatively inexpensive way to screen the view of my neighbor’s house. The problem is that I need to screen about 250-300 feet of a 700 foot lot line!

    Whatever is planted needs to be hardy in zone 5b and at least somewhat effective during the winter. Minimal pruning is necessary because of the sheer amount that will be used. Height needs to be at least 7 feet. I’ve been considering some sort of evergreen. Do you think switchgrass might be a reasonable solution?

    Thanks again for opening my eyes to this new possibility!

    Brian

    I definitely think that ‘Cloud Nine’ could be a good option for you, Brian. If you want grasses that are even taller, consider giant reed (Arundo donax) or ravenna grass (Saccharum ravennae), or the Miscanthus giganteus that Steve suggested. In spring, you could cut any of these down with a brush mower, a string trimmer with a blade attachment, or even a chain saw. Perhaps you’d want to consider a combination of tall perennials and grasses to create a border-like effect. That might be a cheaper route, because then you can use whatever’s easy to find. Hey, here’s another idea to save money: Maybe see if you can get divisions from a gardener in your area through Freecycle.org?
    -Nan

  19. I love your garden and your piqtures.
    I now the feelings with flat garden..we have it to.
    The problem for us with tall perenials is that here in Sweden it rain weru much and they dont like it.
    If you now what I mean.
    Here in Sweden the fall is comming, so now is the time for relaxing, reading garden books for example.
    Regards Ken

    Hi Ken! I understand how it could be difficult to enjoy tall perennials if they are prone to sprawling in rainy conditions. Our summers are often rather dry, so the stems here tend to be pretty sturdy – at least on those I consider my favorites. We’re due for a deluge tonight, though, so we’ll see what stays upright by tomorrow!
    -Nan

  20. I finally got back to read your post!
    As Pam says, it’s like reading an article in one of your books. Very interesting. You’ve shown some fabulous plants!
    I haven’t planted any really tall perennials or grasses because I don’t want to block our view, and our neighbors are far enough away so that we don’t have a privacy issue. We do have some trees (some very large) to give us a wind screen and a bit of privacy, plus lilacs and a few other shrubs.
    Your garden looks wonderful with all the tall perennials Nan. They fit in so well with your house and yard, but in my mind’s eye I just can’t picture them in mine.
    We have surrounding fields full of Joe Pye Weed and goldenrod which are gorgeous, so there’s not really a need for me to grow them. We get to enjoy them without any work invested! :)
    I’d love to fit the ‘Lemon Queen’ in somewhere though, and that Ironweed looks gorgeous. I love the ‘Cloud Nine’ photo especially. That stuff is gorgeous with it’s soft, fuzzy effect, and all those plants look so good together! You sure have a knack for pairing plants.

    Hi Kerri! I like your comment about not having to grow the tall perennials because you can enjoy them in your fields. That’s actually another reason I like them here, because I’m trying to create a visual link between my meadow and my garden. I’m still not sure that I’ve accomplished that, but I think I’m getting there.

    By the way, you were right about the photo of my garden also being on the inside of the Gardening How-To magazine: it’s the same path as on the cover, but looking in the opposite direction. That one too was reversed!
    -Nan

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