Planting within a Retainer Wall

Hello,

We just finished a 2 block retainer walls that are 130 ft long and 6 ft high. This walls are visible from the main road which is 800 ft way and I would like to do something that will be visible from the main road as well as improving the yard. This lower section in between the walls has 1 ft of good black dirt. I thought I might plant Hisbiscus's in this area because the flowers are big. My concern is how will this plant survive the heat from the upper wall if I am not able to water it daily? Are there any other large or showy plants that I could use for this section? I prefer not to use shrubs. I plan to plant informal cottage type flowers with a variety of color in the upper section.

HI Kate :) Welcome to DG :) You've done an amazing job on your wall. I'm not sure what your minds eye sees for this spot. I know you said big or showy but not sure how you define big and showy. Also, are looking for perennials or annuals? I think a mass planting of Salvia nemorosa 'Blue Hill' would be beautiful. http://davesgarden.com/guides/pf/go/81879/ I love the salvia and they attract butterflies and bees as well. This is one that is hardy to your zone for perennial. Some of the other varieties you could plant as annuals if you'd like. Here is an idea of what it could look like http://allthingsplants.com/thread/view_post/143109/ If you don't mind annuals Coleus is a nice choice for showy foliage. http://davesgarden.com/guides/pf/b/Lamiaceae/Solenostemon/none/cultivar/0/ But they do require regular watering. The salvia are drought tolerant. Hope this helps some.

Thank you for the response. Big and showy - something I can see from a distance away. I would prefer a perennial if possible. Since the area is limited in width, I have concerns that taking a wheel barrow or wagon may crush other plants. Hisbiscus can have big flowers. Are you aware of any other plant that may have large flowers?

There are many Dahlias that have extra large blooms and are wonderful flowers. The only thing about them is that you may have to pull and store the tubers each fall in your zone.

I'm going to post a link to this thread in the perennials forum if you don't mind. There are many knowledgable folk there who are more familiar with your zone and may be able to help you out as well.

If you want hibiscus, make sure you plant other things around them too. They die back over the winter and tend to be slow to get going again in the spring, and they don't bloom until pretty late in the season so if you don't plant something else around them you will probably not be happy with how your garden looks during much of the year. You can look for other things with big flowers, but as an alternative planting groups of smaller flowered plants together for masses of color can also give a good look from a distance.

Hibiscus aren't especially drought tolerant, but those beds are deep enough that you shouldn't have to water every day.

How about lilies? Conca d'Or is a beauty and smells heavenly. It will reach 4' or more (count on more). It's a huge flower - about 8" across. The first year it will only be about 2' but the following year will be closer to 4' and then...who knows?

For more lily idea check out B & D Lilies and Plant Files.

What about sedum and coneflowers? Some of my favorites. Some of the low growing sedum would hang over the wall or Sedum 'Neon' a show stopper is an upright. Just another idea.

Hardy Hibiscus do need water to get established plus they die back in the winter and start growing late in the spring. Bloom starts sometime in August. My experience with them is that the blooms are huge but there are not a lot of them on a plant at one time. Something with a mass of blooms might be preferable. Looks like they require winter protection in zone 4 so that might be another thing you might want to review esp. since it looks like they would be in an exposed area.

Most new plants need regular watering to get established so either set a sprinkle hose on a timer, water filled buckets with holes in them, or some other means for regular watering the first year. If you are out far enough from the house that they will never get watered much and heat from the back wall maybe an issue then look at xeriscaping type plants. I frequently look at High Country Gardens’ on-line catalog to get ideas for xeriscaping plants to go at the back of our yard. We rarely water the back fence area of our yard.

I understand about wanting to plant all perennials. My comment on it is that a combination of evergreens, small ornamentals trees, shrubs, and perennials will give you a variation of bloom times, seasonal interest, height, and textures plus provide a windbreak or screening if needed.

Am I understanding correctly, you will be planting the lower section with perenns. and want them as tall as possible? If so I got scads of suggestions as I LOVE large and tall plants. Also what is the width of the flower bed? I also have plant suggestions for some that would over hang the wall, might help to insulate for areas where the plant material is not the 6' ht.. My border is 45ft.X100ft., which is outlined with tall plants, both annuals and perenns. . What is your zone? I am in zone 5 personally. One hint....from a distance darker flower colors are lost and would blend into the wall, so lighter colors are best to be seen from a distance. what is the direction of the wall, does the sun have direct contact with the face of the wall? Does the wall taper to a lower height at the ends? Are you also interested in any tall grasses? Will you be growing any from seed or do you have an unlimited budget? lol. And remember there are plenty of people here that will do trades with you come spring (both for seed and plants), I have seeds for many tall things if interested in starting anything this winter. Have to run for now be back in a bit to start listing goodies for you. Kathy.

What about Peonies?

All, thank you for the responses, so many ideas to consider. I will check out the High Country Gardens and Xeriscaping. I have not heard this term Xeroscaping before. As for the wall, yes it does taper down at the end. I will be able to walk from the yard onto the 1st level. In that section, I thought it might be work to plant rock cress or another slow creeping plant. I want something durable if the kids or dog would happen to walk on it. Then I would plant something a bit taller and eventually get to the larger plants. The wall faces south and gets sun most of the day. The house is Northwest and blocks the wind from the north. I am trying to avoid shrubs because I have concerns with the deep roots. If there is ever a need to pull the plant, I do not want to dig it out by hand, and to pull over the lower wall or upper wall with something stronger could damage or shift the walls. Adding a few different types of flowers sounds like a good idea. Maybe placing some Clematis vine against the back wall, then placing a few Hisbiscus with the Lillys would work. On the edge of the wall, I have placed buckets and thought I would plant Petunias in the buckets this year and maybe other annuals around the Petunias. I will be able to water every day for the first year and would prefer watering less years after. My biggest concern, is making sure the garden would survive if I was to take a week long vacation. This area is considered zone 4a. I have added pictures to help show a bit more of what I am working with

This message was edited Dec 29, 2011 8:38 PM

One more picture, the buckets will be in the ground this year.

Lol, you forgot to mention how wide the bed is. Ok, to start with a few that will hang over the upper edge if needed: creeping Phlox; Saponaria ocymoides, spring, trails to 3ft, pink.
TALL up to 6ft: Alcea (hollyhock); Salvia azurea 4'; Crambe cordifolia,4-5'; Thalictrum; Filipendula 4'; Iris japonica or siberean; Veronicastrum virginicum; Eupatorium m. phantom Joicus (white) and m. Gateway 5-6'; Cosmos b ( can use these to fill in till ou get more perenns. I have plenty of extra seed for postage, annual); Boltonia asteroides 48-60"; Agastache X Ava, 4-5', rose; Cimicifuga racemosa Bugbane, 50"X15"; Aruncus dioicus Goatsbeard, 40-72"X2-5'; Campanula pyramidalis, 4-6'; Aster lateriflorus Lady in Black, 36-48"; Aconitum h. Spark's Variety, 30-50"; Lobeilia; Malva; Salvia Nekan Pitchers Sage; Monarda d. 36-48"; Helianthus; Helianthemum; Lobeilia hyb. Deep Red Compliment, 3'X2'; Lupinus 48"; Achillea fillipendula Coronation Gold, 48"; Trollius chinensis 24-48"; Phlox paniculata 48", best is the midew resistant varieties of "David" or those related; Leucanthemum (daisy) Becky, 48"; Limonium latifolium, 36-48"X48"; Veronicastrum virginicum or sibericum, 48-72"X36"; Agastache ( there are several tall ones); Coreopsis tripteris, 48-60"; Platycodon grandiflorum, up to 48"; Campanula lactiflora or latifolia, 36-48"; Lilies--Orientalis some to 48"--Asiatics 36-48" (reseeds and multiplies)--Trumpets 48-60"--Tigrinums 36-48", reseeds, leaf axiles produce bulbils which drop and sprout a root to pull them into the soil--regale 60"; Valariana officinalis, 48"; Physostegia v. 48" pink or white; Solidago canadensis, 48"; Baptisia austraulis, 48"; Daucus carota, 48-72"X48-60"; Delphinium 48-72".
A mass planting in the back of the border will give a block of color effect to be seen at a distance (ie 3-5 plants), sometimes this takes years if you need to multiply plants by division or starting any of these by seed. Personally I use Cosoms as filler til I can get large enough plants or waiting til babies fill in and up.
If wanting to grow any from seed I do have some of these available ( postage). If not try some trades this spring or in the beginner's forum for donations for postage. Just a few ideas for you to think of and or try, all of these I have or am currently growing (90%). Good Luck. Kathy.

Just another note for you, you probably don't need to water daily, once established most plants can grow sufficiently with approximately 1" of precipt. a week. Living in the land of a thousand lakes you get rain which can be deducted from the 1" amount. Also mulching the ground in between plants does help retain moisture, hence requiring less watering. If you do water every day you risk plants not growing roots deeply and many dying out from saturation. Since the site looks level a soaker hose could be added on top of the ground but under mulch. Walmart sells the soaker hoses. I have used grass clipping (from the neighbor's lawn, dried of course), as a cheap mulch, or leaves. Both add organics to the soil with worms galore helping to airate the soil. Kathy.

Wow, I will need to look up many of these plants, thank you. LOL, I missed the width of the bed, it is 5ft to 6ft wide, getting a bit wider in the middle. I see Catzgalore mentioned Peonies. I have always been reluctant to plant Peonies because my sister ended up with Red biting ants around her plants. Not sure what I could do to keep the ants away without a lot of work or pesticides. Other than that Peonies are a great option with flowers that bloom for a long time.
One last question. I can develop a plan in my mind of how the wall would look based upon the plants I chose, but sometime it is nice to create a drawing. Are their any free software programs that are easy to use, dummy proof, that I could create picture with?

Agree that you don't need to water daily. Once or twice a week depending on how dry or how hot the weather is should go it.

Looking at the photo with the buckets and petunias, it seems like that height is about the right height of plants that should go on that wall. When I’m getting ready to plan an area I will go out and set items (buckets, chairs, poles, etc.) out to test out various heights to see what works in the that spot.

Rainfall map shows you at 20-30 inches of rain a year. So you should be able to use those plants at that are Xeriscape but not those that are clasified as Very Xeriscape. http://www.highcountrygardens.com/where-you-garden/

List of long blooming perennials from UMN. Of the items on the list I would stay away from Russian Sage as it sends out runners and will periodically have to be trimmed back. http://www.extension.umn.edu/distribution/horticulture/components/08464-long-blooming-perennials.pdf

List of plants that handle tough sites. The above article is from that page. Also found on that page are articles on “annuals 3 feet or more”, “annual vines that grow quickly”, "Dry soil: annual foliage plants” and “Steep Slopes”. The last article lists plants that prevent soil erosion and the site is difficult to mow or maintain. http://www.extension.umn.edu/distribution/horticulture/dg8464.html

Kate the list of plants was for the back of the border, you can mix shorter plants in the front. Yes peonies do attract ants in the spring. They are eating the nectar on the buds and do no harm to the plant itself. My first peony was sold to me with the offer to also sell me the ants needed to open the blooms. LOL. I didn't know any better and looked at him dumbfounded and then he laughed and said they would show up on their own, am sorry to hear they happen to be red ants though. You could probably spray in the spring til they are all bloomed out when necessary, I only get black ants on mine. Peonies do love water in the spring and once established they are quite drought tolerant. Another great benefit is many turn autunm colors in the fall; golds, oranges and some are red. They just happen to be one of my all time favs. Kathy.

Well I'd say living in MN and Zone 4, your summer heat is not nearly as bad as it is in areas further south, so watering should not be your main concern. As others have mentioned, about one inch per week should suffice. Timers and drip/soaker hoses are cheap and convenient. Look through some catalogs for pictures of plants that interest you, then check back here in the Garden Watchdog for reviews of the companies. That's how I discovered DG; by checking the Watchdog for a company AFTER I had ordered from them with terrible results! Good luck and let us see some pictures after you get it going. It should be beautiful.

As an afterthought, I would also think about mixing size AND texture. The flowerbed is for YOUR enjoyment too, not just the passing motorists.

Doug

Very nice, Doug. Love the trellis with the clematis!

Thanks pirl. You can't see it in this picture but I have one on each backside of the arbor too. They finally grew enough this past year to climb up on the top of the arbor. I planted a climbing hydrangea on the left side this past year too. Don't know how long it will take before we can enjoy it! We had a 'Stairway To Heaven' climbing rose on there the first year but it died after 2-3 years so I gave up on climbing roses....

Doug

Pic of when it was "fresh".

Lovely tranquil setting and very nice design.

I gave up on climbing roses long ago. They are a lot of work!

Doug,

Love the retaining wall picture, it helps with some ideas, I have a back retaining wall that suit this look. Can you share some of the flowers that are in the front right level. I like the clump look and some may work if I do not have them already. As for pictures, I am sure I will share. This site has provided much help from many people and I would like to show them how their imput pays off.

Kate

Kate some of the ones on the right are Tritoma, Gaillardia and Echinacea. I absolutely love the Gaillardias. We've had 'Arizona Sun' now for about three years and it never ceases to amaze me with it's bloom time. This past year it bloomed from April thru November non-stop. You don't usually get that extensive bloom time from perennials. I plan on buying more this year, although my personal forte is shade gardening. My wife planted this bed.

Doug

Hi Kate, you sound just like all us gardeners when we were starting off trying to plant the garden we dream off.
My advice for amateurs on designing beds, borders, or yards is to take a picture of the house AND area you are planning IF it is seen from the house.
Next blow the picture to a much larger size and stick this to a board, cover the pic and board with tracing paper and draw the shape of bed / border you have, add any other structures like hard landscaping(foot paths, trellis, ponds, garages, drains, lights etc so as you plant, you know you have to make arrangements for these structures, this should also include windows/ doors too.
Next step is the best, test your soil to find out the the type of soil you have as this will be a clear indication of what you CANT grow, then(like painting by numbers) Begin to colour and draw the shapes for plants you like, little squiggly circles will make small shrubs or ground cover plants, tall bushy shapes for larger shrubs and taller thin shapes represent tall slender plants like fox gloves or Delphiniums etc, wavy circles on the wall will show plants that tumble over the wall, you can keep a list of the plants you want at the side of the drawing and rub out / add as you go along with the plan, you can also add the paint colour you fancy for the wall etc IF that is part of the plan too, there is no end to what you can then add to the plan and if you get taken away from your drawing, then you have your thoughts down on paper to pick up where you left off and also allows you to have a complete plan but to just do a block of planting at a time because plants are expensive, also this gives you the time to research where to get all the plants you fancy, changes made are easy too. Hope this helps you out. good luck. WeeNel.

Thanks for sharing. As here I have learn so many interesting and informative things.

Hi ExpertVGL, good to know you are enjoying the site, did you know there is also an Australian forum on Dave's Garden site where there are many friendly people who will be willing to help answer any questions you have while growing plants in your local area.
Best Regards, Weenel.

Designing a garden on a surface that isn’t flat always presents extra challenges to a gardener or designer. A sloping piece of land with different levels can make a visually interesting garden, but creating workable garden spaces can be problematic. The beauty of retaining walls is that they provide a way of changing level abruptly, and that is especially useful if space is tight. There are two main considerations for anyone wishing to hold back earth with a retaining wall. Firstly, the wall must be strong enough to hold the weight of soil behind it. Secondly, it should be able to cope with problems caused by the moisture that will percolate through the ground. Thanks.