I agree, it’s very hungry, especially for Nitrogen I think, the lack of can cause leaves to yellow uniformly like that.
In the same compost for 3 years and only fed some Toprose. The latter has an NPK of 5-6-12 + magnesium and iron. The N for nitrogen is pretty low. A seaweed tonic won’t resolve that. The leaf spotting is incidental.
Normally for potted roses I replace the top couple of inches of compost every spring, feed a slow release rose fertiliser with a better balance of NPK and micronutrients twice-yearly in spring and summer and feed a weak liquid feed every week or two.
As others have said, nutrients get washed out of the pot easily and the rose can’t go searching for them in the ground - they are dependent on you replacing them.
I kept GJ going in a very large pot for 5 years with that feeding regime but eventually it declined and had to come out. I planted it in the ground but you can knock off the old compost, prune those vigorous roots back and replace it in the same pot in fresh potting mix. The JI3 with some compost added for drainage is good, I also mix in a spadeful of garden soil and one of composted manure.
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
Thank you so much for your advice, some deep Rose knowledge out there!
I only properly got into rose growing about three years ago, so I am a really still a total newbie.
I just have the option to garden in containers, ground is not available.
So, to sum up your erudite advice:
Remedy nutrient deficiency
Use foliar spray, e.g. seaweed
Replace 2in of compost with JI3
Use Epsom salts to replenish iron & magnesium (15ml in 5l water)
Feed with a slow-release rose fertiliser with higher nitrogen (Toprose has 5-6-12 = low N)
Don’t overwater
Water deeply every 3 to 4 days
If the compost feels moist, there is no need to water
Use pot feet
Root-prune and re-pot
Use JI3 + MPC, add manure
Maybe not the best idea to grow a climber in a container…
I’m really glad I asked this question, I found out loads about growing roses in containers.
Some bonus questions
What do you think of Supagrow instead of garden compost (which I do not have) mixed into rose potting mix? And when I top-dress the containers, could I mix JI3 with Supagrow for extra rose happiness?
Do you know a rose fertiliser that is high in nitrogen, the ones I know are both only around 5.
For the weekly/biweekly feed, I use Tomorite diluted to half its strength. Is there something better?
No need to pile absolutely everything on, you don’t want to overfeed a poorly rose either! A slow release food will also cover the magnesium so you don’t need epsom salts too; a liquid feed will give an instant boost, as would a foliar feed, but again you don’t need both and the latter on poorly, yellowing leaves won’t help if they are about to drop.
Miracle Gro Rose and Shrub Continuous Release Plant Food NPK 22-7-14 plus magnesium etc. is a good one and widely available. Another good one, especially if your water is very hard (alkaline) is Vitax Azalea, Rhodo and Shrub Fertiliser NPK 9-7.5-10.2 + iron, magnesium, micronutrients. The latter is the same formula as David Austin’s old rose food although I favour the miracle gro for potted roses.
Tomorite is potassium (K) that’s helpful for blooms, but I’d be inclined to use a more balanced liquid feed at first, until your rose has reacquired a healthy set of green leaves. I would then use the tomato food later to encourage re-blooming.
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
Thank you @Nollie, I’m a big fan of thoroughness. I will update my notes and get some of that Miracle Gro. I find feeding / fertilisers very confusing.
I’ve not been very good with mulching and top-dressing because I have lovely miniature plant worlds growing around my roses. I guess I will have to move them. *sigh*
That does look really pretty, but other plants in the pot will also be competing for nutrients. Why not forget the new mulch for now, enjoy the display for the summer, then sort the mulch out later? Hopefully the slow release + liquid feeding should be enough for now. Annuals in rose pots are usually easier because they don’t get in the way of re-mulching and as the roses grow more and fill out you may find there is little space for them anyway. You can always plant other stuff in separate pots around the roses to get a similar effect.
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
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Normally for potted roses I replace the top couple of inches of compost every spring, feed a slow release rose fertiliser with a better balance of NPK and micronutrients twice-yearly in spring and summer and feed a weak liquid feed every week or two.
As others have said, nutrients get washed out of the pot easily and the rose can’t go searching for them in the ground - they are dependent on you replacing them.
I kept GJ going in a very large pot for 5 years with that feeding regime but eventually it declined and had to come out. I planted it in the ground but you can knock off the old compost, prune those vigorous roots back and replace it in the same pot in fresh potting mix. The JI3 with some compost added for drainage is good, I also mix in a spadeful of garden soil and one of composted manure.
Thank you so much for your advice, some deep Rose knowledge out there!
I only properly got into rose growing about three years ago, so I am a really still a total newbie.
I just have the option to garden in containers, ground is not available.
So, to sum up your erudite advice:
I’m really glad I asked this question, I found out loads about growing roses in containers.
Some bonus questions
What do you think of Supagrow instead of garden compost (which I do not have) mixed into rose potting mix? And when I top-dress the containers, could I mix JI3 with Supagrow for extra rose happiness?
Do you know a rose fertiliser that is high in nitrogen, the ones I know are both only around 5.
For the weekly/biweekly feed, I use Tomorite diluted to half its strength. Is there something better?
🪷🪷🪷
Miracle Gro Rose and Shrub Continuous Release Plant Food NPK 22-7-14 plus magnesium etc. is a good one and widely available. Another good one, especially if your water is very hard (alkaline) is Vitax Azalea, Rhodo and Shrub Fertiliser NPK 9-7.5-10.2 + iron, magnesium, micronutrients. The latter is the same formula as David Austin’s old rose food although I favour the miracle gro for potted roses.
Tomorite is potassium (K) that’s helpful for blooms, but I’d be inclined to use a more balanced liquid feed at first, until your rose has reacquired a healthy set of green leaves. I would then use the tomato food later to encourage re-blooming.
I’ve not been very good with mulching and top-dressing because I have lovely miniature plant worlds growing around my roses. I guess I will have to move them. *sigh*