Nutrient deficiency or cold wet soil?

12 years ago

I have a bed of knockouts that are showing what I think is a nutrient deficiency (nitrogen or iron?). However, within the same bed a few of the roses are just fine. The raised bed is 18 ft wide by 3 ft long and is along my walkway.

The soil had been added to as a topdressing last summer with compost I made with year old horse manure, leaves, etc. I then topdressed in fall with hardwood mulch from my local garden center. I have not tilled in anything, just top dressed.

The bed gets mostly sun to part sun (most sun in the afternoon) and sits on the north side of my house.

I did fertilize beginning of May with blood meal and potash, then the problem continued so I added about 1 to 2 Tbsp of iron sulfate to the whole bed. I also sprinkled over the whole bed some Osmocote. about 2 weeks ago. I don't want to feritlize anymore but I don't know what's causing the yellowing. It looked to me like iron or nitrogen but the bottom leaves are turning yellow now. What gives? How can some roses do fine and others not in the same bed? lol

The first pic is of the problem with the roses
The second pic is the "just fine" ones.

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Comments (5)

kentstar
Original Author
12 years ago
Here's the second pic of normal looking growth one
michaelg
12 years ago
Recommended application rate for iron sulfate is 1/2 to 1 cup per 100 square feet, or up to 2 TB per plant. The amount you applied wouldn't have any effect.

I am not sure of the iron diagnosis because the chlorotic leaves do not show green veins--as they would except in severe cases. The veins appear reddish on my monitor.

Usually with N deficiency the plant is evenly pale green all over.

You might want to check the pH. Residential soils can have odd spots where the contractor buried concrete, plaster, etc. Also a big rock under the plant can cause localized drainage issues.

A few solid-yellow leaves at the bottom don't necessarily mean anything.
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jim1961 Central Pennsylvania Zone 6a
12 years ago
The first pic looks like it may be showing green veins on my monitor ...

Maybe take a closeup pic of effected leaves...
michaelg
12 years ago
How deep is the horse manure? If they are growing in mostly manure instead of soil, that's a pretty unnatural situation.
kentstar
Original Author
12 years ago
I got the horse manure last spring 2013 from a coworkers farm and she said it had been piled up and left all winter long before I got a hold of it. I used it in my compost bin to compost even more over last summer and just laid the compost on top of the soil as a top dressing.
I will try to get a close up of a leaf if I can, it's raining right now.