Q. I think it’s soon, but I can’t remember, when should I fertilize my roses for the last time this year? – A.B., Albuquerque
If you feel the need to fertilize the roses and it has been weeks since their last feed, do it, but do it NOW. I caution you that if you fertilize too late in the year – and roses being a bit peculiar at times – they just might want to force out a bunch of new growth rather than thinking about hunkering down for the impending winter months.
So please, if you can’t fertilize this weekend – and no later than that – wait until mid-March of next year. Granted, it’s been wicked hot and we’re not thinking about winter, but it’s time to settle things down, not encourage a bunch of tender new growth. Certainly continue to water, but no more fertilizer. Again, a big oops on my part.
Now, you say these plants live at a house that is sitting vacant. My questions to you are, how often do you go there and water? How are the roses watered? Are there wells or moats surrounding the bushes that are slowly filled with water? Were the bushes watered at least weekly to every ten days this growing season?
Reason I ask is, to me (and know that I’m not a plant pathologist), they look like they have been pulling up a lot of salt when they were/are watered, trying to pull up as much water as they could.
When plants are tended to faithfully and then the tending stops, or at least gets altered, they rush to grab what they can, when they can. Then to compound the issue, the soils we have in this neck of the woods are typically very alkaline (salty), making it troublesome for the plant life at times.
To me, the leaf sample I got from you looks haggard. The crispy leaf edges show a tell-tale struggle to get the water they needed, when they needed it. The “white” could be a disease called powdery mildew, but it doesn’t wipe off, which is why I’m leaning to a salt accumulation in the leaves. I’m just not sure.
I have to ask if the bushes are planted next to an area that might have been treated with a weed killer? If so, maybe just enough of the chemical was pulled up by the rose to mar the edges of the leaves. One nifty thing is I didn’t see one bug on your sample, so the bushes are healthy in that respect.
I would strongly suggest that this winter, as the leaves fall off the bushes, they get raked up and removed. If part of the problem on your sample is powdery mildew, the easiest way to treat it is make sure to keep the old leaves raked up. A lot of fungal infections happen because last year’s leaves aren’t tidied up, the fungus overwinters and then when conditions are right, it happens again.
But to me, it looks like the roses pulled up a lot of the salt that occurs naturally around here and burnt themselves.
Also, consider spraying the bushes with a dormant oil this winter to help suffocate fungal spores that might be part of the malady the roses are dealing with.
Truly, to me it looks like the roses weren’t getting the deep water they needed consistently and they got a salty sunburn. I hope the roses turn around for you and regain their health.
Happy Diggin In.
Tracey Fitzgibbon is a certified nurseryman. Send garden-related questions to Digging In, Albuquerque Journal, 7777 Jefferson NE, Albuquerque, NM 87109, or to email@example.com.