That should not have been the cause of the stunting. Were the leaves discolored? If roses can be grown in the ground in southern California the alkalinity of a concrete planter should not faze them.

My first idea before I had even finished reading your thread was that the concrete blocks heated up so much and there was so litte air surrounding the tiny roses that they were stunted from the heat and lack of air. When you stated that the acid helped the rose I had to discard that idea, although I still wonder whether this still might not be the ideal habitat for your roses.

Ingrid

Ingrid - I just went out and felt the concrete things - they are actually pretty cool - much cooler than the air or the soil. They are porous, so perhaps the evaporating water is keeping them cool. They are only 2 inches thick - they are, my DH tells me, intended to be used as "tree rings". The diameter of the dirt is 24 inches, and I used potting soil, so I don't think it is lack of air either.

I just ran around the garden, and realized that instead of 3 of these things, we actually have 7. In six out of the seven cases the roses are not growing. The seventh one is actually a mature Buff Beauty where we replaced a rotting half wine barrel with these concrete things, after it had already gotten huge. After the success with SL I poured acid loving plant food all over the other six today. Will have to see what happens - I'll keep you posted. I have told my DH that I really appreciate his efforts, but I think we have to stop building these containers!

Jackie

Well, this is very interesting to me. Please do keep us posted. I have a large raised round bed in front made out of those concrete things - with, of course, roses in them. It's not that old, so I can't say that the roses have been stunted, but would still like to know if I need to keep an eye out for this. Thanks for posting.

Jackie,
You can test the potting soil pH easily, by the way. The Rapitest ph Meter is $12 or $15. All you need is the meter and distilled water to wet the soil. It works well. I've confirmed pH with soils test four different times.

I can think of other possible problems that may pile up with the concrete leaching lime. First, water is the obvious one. How well does the potting soil inside these porous planters hold water? I'm always concerned about water retention in raised beds. Second, did you create an unnatural soil horizon? You've placed one kind of oil on top of another very different soil. Did you break the garden soil and mix some into the pottting soils before you planted? The conventional wisdom is that root growth is restrained by soil horizons. Third, maybe there's something wrong with the potting soil. Don't scoff. The formulas change all the time. I've found potting soils have gotten worse and worse. I only use a couple of kinds. Actually, I buy it by the pickup load and amend it. Many potting soils have virtually no nutrients and little water-holding capacity. Fourth, have you thought it might be time to do an autopsy if the acid plant food doesn't work? Dig a real hole later in October, just like you ordinarily would. (Did I tell you I have a jackhammer just for this?) Anyway, move one of those roses and get a good look at at the soil a foot down and what's going on with the roots.

Hi Jacqueline,

I don't think you're stupid. As I was reading this, I thought (what a great idea). Then I read a little further and decided to see how it turns out for you. If you want to talk about stupid I planted and re-planted the same hydrangea tree 3 times in the last week. Now that would probably be considered stupid.

Good luck with your roses,
Kitty

I am inclined to agree with Cass, that the potting soil is likely to be deficient in a number of ways. Most multi-purpose potting soils have been developed for short term container planting, for use with bedding plants over one growing season. Unless the soil is actually loam based, the medium may consist of little more than coconut/coir, some peat and usually about 6 weeks worth of nutrients. The structure of the potting medium changes with watering and amendments and the drainage may be too high so water is not retained for long enough. Conversely, you could also be getting a sump effect where the new potting mix has been added to the old ground soil.
We are landscapers and appreciate that lime can be an issue but most concrete, these days, tends to be extremely stable - we have been using concrete blocks for raised beds for years with no problems, even with ericaceous planting.
I would also agree that further investigation is necessary so either dismantle one of the containers or excavate a hole to really see just what is going on at the ground level and with the roots. Good Luck, and keep us updated.

I'm with Cass on this. I've had roses grow poorly right in the ground because I think perhaps the stuff I used to backfill the hole wasn't good. That was a neat idea about the planters.

Thanks so much for all of the good suggestions! Cass, I do intend to test the PH and do some investigating.

At the moment, however, we are in the middle of "de-bagging" and "de-tying up", and pruning, mulching, re-tying up, and feeding all of our roses and other plants all around our house, because the scaffolding is finally down (yay!), and the painters have moved on to the garage. So, I don't have lots of time right now to spend on these containers, and my main concern is to see if I can feed & water them enough to make the roses happier, and then I will play Sherlock Holmes later. I did think of the water issue when I noticed they were not growing, so I have been giving them extra water for a while. I felt so guilty when I thought of the PH issue that I went out and bought a bunch of that MAXSEA plant food (the kind for acid loving plants) , which is really expensive, but will be worth it if it works on the others as it is working on Susan Louise. Thinking about it, if pour planting soil was the issue, that might explain the immediate response to the food, although I was giving them normal food before.

We have had the "soil horizon" issue here before, because our soil is very much clay. Last year I transplanted a Margo Koster, which died within 6 months. When we dug it up we discovered that in digging it a "big hole" what we had really done was dig it a bathtub that didn't drain, because the clay was so dense. Anyway, that certainly might be an issue. However, the 7 containers are all over the garden, and in some places are in beds that have been amended & planted for decades, where the soil is in pretty good shape.

I will keep you posted on what I find out, and how they do with their new food. Thanks again for all of the good suggestions.

jackie

I also think that the potting soil might be an issue, rather than the containers. I had numerous plants failing just because the pot soil was crap - after all, for mass production they definitely do not wait for the natural decomposing to produce enough soil.