Excellent question. I will be following this.

Hopefully Al himself will comment.

And hopefully he can be induced to periodically comment on Rose forum discussions about soil composition when growing roses in the ground.

I wonder if you do almost a pot in pot with the rose in the inner pot and the succulents in the outer pot around the rose., you might be able to get away with it easier.

Yes, Ann's idea is what might work. I just can't see hungry roses, particularly climbers, being satisfied with a lean cactus mix. Diane

Thanks Ann and Diane! I suppose I could put dividers in the bed to make sections. How much space do you think the roots of a climbing rose should need? I'll start searching the rose forum for soil / fert recommendations etc, since I've never grown roses before.

Hate to be a downer to this discussion but combining roses with droughty succulents like aloes sounds like a very poor idea. And I have serious reservations about the drainage offered by a closed bottomed planter as well.

FWIW, roses can produce some significant root systems and climbing roses generate even larger ones to compensate for their extended growth and size. Your planter is not going to keep them happy for long without root pruning or sacrificing much of their size,

Growing in a container or planter as described requires a very different approach than it does for inground gardening so your best info about soils and fertilizing is going to come from the Container Gardening forum, not from the Rose forum. The soil mix should fit the water demands of the plant in question, which is why combining two types of plants with extremely opposing water needs poses all sorts of problems.

Thanks for the input gardengal! I should clarify, the planter will have drainage holes. By closed bottom, I just meant to differentiate it from a raised bed. I may ditch the idea of adding in Aloes, as it sounds like a tough combo. But it sounds like even on their own, you think climbers may not have enough space in this type of box? Good news is I haven't built the box yet, so I can adjust size :) Is there a recommended size planter box that could sustain a climber decently?

Plan on something the equivalent volume of a half whiskey barrel. For each rose.

Steven, there are plenty of rose growers on this forum who grow extensive numbers of roses in containers and do very well. I hope they see this thread to offer their advice. Diane

Thinking a bit more about the growing medium for a big climber in a large planter. Given the impracticality of regular repotting, is there a way to create a mix that will retain structure for a long time (similar to gritty mix), but still provide enough nutrient / water retention to make the roses happy? A lot of the soil recommendations for roses I have seen in searching around include a lot of organics that I'm wondering if they will break down too quickly over time.

Assuming I were to fertilize regularly and often enough with watering to provide sufficient nutrients (Foliage pro 9-3-6, eg), is there a need for any organic nutrients in the medium itself?

And would the benefits of the aerated mix and its longevity outweigh the trouble of more frequent watering / fertilizing? To me, the chore of frequent watering/fertilizing doesn't seem as daunting as the nightmare of repotting the beast, unless I would be watering multiple times per day (no thanks). So I guess the question is do you think a chunky inorganic mix will have me watering multiple times per day to keep roses happy?

I'm in San Diego (Zone 10?). Location is an atrium wall that gets about 1/2 day of strong sun against a white wall.

I can easily find locally: pumice, Turface, granite, perlite. Maybe some combination of these plus a small amount of peat (small enough that its breakdown wouldn't cause too much problem over time)?

Does Turface hold more water than pumice? And would adding more Turface to a mix increase water retention?

Or do roses' roots prefer a soil with finer particles?

Thanks, and sorry for the long reply, I'm having fun learning!

I tried growing roses in pots with the 5-1-1 method, and I found it didn't work very well. BUT, maybe I didn't do it right or something. I'm going back to richer soil, like I had when my roses used to do wonderfully. The last 4 years I've been trying 5-1-1...and...I didn't like the results. Don't base your decision on what I'm saying though. Just see if other people chime in and agree/disagree with me. I'm just one vote.

Whatever you do...I hope it works wonderfully for you!! :)

Hi @Steven

Do you already have the roses? Which variety are they?

I am in zone 11, so similar to yours, and all my roses are in containers. Here's some advice that I wish I had known before I got my first roses.

In our warm climates, many roses grow far bigger than their stated heights.

Many of the roses sold as climbers become absolutely gigantic. So it is useful to check out HMF and forum posts about the true max height a rose can grow in your zone.

As it turns out, many of the roses sold as shrubs can be trained as climbers, especially in warm climates.

Choosing such a rose would allow you to get the climber effect on your wall, without having to deal with quite such an extensive root system as true climbers.

Thanks @seasiderooftoop!

I have 3 David Austin varieties that I got as own root roses from Heirloom Roses. They are Don Juan, Mme Alfred Carrier, and Zepherine Drouhin.

The wall space is quite large, especially vertically. This pic shows the location. All the stuff in front of the wall will be cleared out to make room for the planter.

Looks like the pic didn't post

Looks like the pic didn't post

Steven, none of those are David Austin roses :-) Both the Madame and ZD are considered 'antiques', being introduced in the 19th century (long before David Austin was even a glimmer in his parents' eye !). And both can get very large, although a container with a limited root run will keep them smaller.

But if you have them and like them, then it's worth experimenting.

I had another response typed out to the soil and fertilizing questions but somehow my computer ate it before I could post. For your situation, I would not choose the standard gritty mix as I think your watering demands would be excessive. I would either modify that recipe to provide more moisture retention or select another. I use the 5-1-1 mix for ALL my outdoor containers and I have a lot.....40+ at last count. They are outside 365 days a year, fully exposed to all the elements and include a lot of trees and shrubs, including roses. Several I have had for more than 25 years.

Contrary to what many rose growers would have you believe, roses DO NOT require a fancy, enriched soil or an elaborate fertilizing regime. They are just another flowering shrub, much like any other and you can treat them exactly the same and they will flourish for you.

ps. I also use the Dyna Gro 9-3-6 for all my containerized plants, together with a dose of Osmocote at the beginning of the growing season.

@Steven

Per HelpMeFind:
DJ: Height of 12' to 14' (365 to 425 cm). Width not stated.
MAC: Height of 8' to 25' (245 to 760 cm). Width of 10' (305 cm).
ZD: Height of 10' to 15' (305 to 455 cm). Width of 6' to 8' (185 to 245 cm).

Please note the width! Consider that each will take up about 3 meters (10ft) in width on your wall.
The stems will definitely need to be fanned out sideways against a trellis, or upwards but in a snaking pattern, so each rose will end up taking up a lot of space horizontally too.
If you train the stems vertically only, you will mostly get blooms at the top, which will be far from where you can enjoy them. To encourage blooming all the way from bottom to the top it is important to curve the stems as you trellis them.

They will fill up your wall space horizontally faster than you think! Do you intend to cover the whole wall with a trellis? I hope you have a tall ladder, you will need it to tie up the stems way up there when they get really big!

Diane - GASP!!!

Just wanted to show how big those climbers can get. Here's her Eden, followed by my small Colette. Diane

Colette is considered to be a small climber. Diane

Steven, I would try a rose potting mix in pots/planters and fertilize with Osmocote Plus twice per year.

I would put the succulents in succulent purchased soil in a separate pots. That would make a nice grouping.

Diane - your Colette is a show stopper...what a stunner!!

@gardengal48 (PNW Z8/9)

"Steven, none of those are David Austin roses :-)"

Oh wow, haha. I guess I just assumed since they were listed on the DA website that they were his varieties, oops. Thanks for the info!

"I would either modify that recipe to provide more moisture retention or select another."

What would be the best way to modify? Add more Turface, or add peat? Maybe I'll try the 5-1-1. Do you find you have to repot often? That's my biggest worry with the climbers. Also sourcing the correct size bark. Then again, maybe I can build the planter so the front panel swings open so I can repot and prune roots from the side while it hangs itself from the trellis...! With roses in a 5-1-1 how often and at what strength would you recommend fertilizing with DynaGro?

Thanks!

@Diane Brakefield

Thanks for posting all those pics, they are lovely! And I can see they can get massive!

@seasiderooftop

I had never heard of HMF, cool resource, thanks! Yes, the width is definitely the factor is seems. If I were to plant 2 varieties in there and their canes overlapped each other would that work? Or would it look funny? Or Maybe I can do one as a fan, and one or two as pillars in the corners? I plan on building a big trellis frame by running a cross beam between the tops of the two low rooftops and adding framing and wiring. The trellis will probably stop at the low roof height, since I don't want to die pruning.

Yes, hmf is a GREAT resource!!! I don't know what I'd do without it!!