Mottled leaves on Butterfly weed - Ask Extension
This plant has been in my garden for a few years, I have never seen the foliage looking this way. The plant is approx 2 feet tall and you can see that...
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Mottled leaves on Butterfly weed #837973
Asked June 28, 2023, 1:05 AM EDT
This plant has been in my garden for a few years, I have never seen the foliage looking this way. The plant is approx 2 feet tall and you can see that some of the leaves seem unaffected. I have another Butterfly Weed- the Hello Yellow in a different area of the garden which is showing signs of the same yellowing on lower leaves to a much lesser degree..
Both are in full sun and I water them only when my soil moisture reader indicates they are getting dry.
I am so upset because I look forward all year to seeing Monarchs and their caterpillars each summer (See photo C - the same plant last summer).
In my own research I have read that the plants may need thinning for better air circulation. But I hate to thin them if that's not the answer. Any advice would be most greatly appreciated.
Baltimore County Maryland
Expert Response
Don't be too upset. I'm not seeing monarch or swallowtail caterpillars in my pollinator garden yet, but they will come.
We are not sure about the cause of your yellowing leaves.
Do you see anything on the undersides? We would check for thrips and mites, which are really tiny and can be hard to see. You can do what is called a 'tap test', by putting a piece of white paper under a branch and giving it a good tap/shake over the paper. Use a magnifying glass If your eyes if they are really good, (otherwise a magnifying glass will help) to look for tiny dots moving across the page. You could gently spray water and wipe off leaf undersides to see if that helps.
This page can tell you more information about your Butterfly weed (Asclepias tuberosa):
https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b490
Too much water can cause leaf yellowing.
This plant wants soil on the dry side, and it must drain well. Once established, they can even take drought. (Moisture meters tend to be inaccurate. Sticking a dowel or screwdriver into soil and then feeling with your finger is usually all the info you need).
Christine
We are not sure about the cause of your yellowing leaves.
Do you see anything on the undersides? We would check for thrips and mites, which are really tiny and can be hard to see. You can do what is called a 'tap test', by putting a piece of white paper under a branch and giving it a good tap/shake over the paper. Use a magnifying glass If your eyes if they are really good, (otherwise a magnifying glass will help) to look for tiny dots moving across the page. You could gently spray water and wipe off leaf undersides to see if that helps.
This page can tell you more information about your Butterfly weed (Asclepias tuberosa):
https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b490
Too much water can cause leaf yellowing.
This plant wants soil on the dry side, and it must drain well. Once established, they can even take drought. (Moisture meters tend to be inaccurate. Sticking a dowel or screwdriver into soil and then feeling with your finger is usually all the info you need).
Christine
Thanks so much for your advice. I'll follow your suggestions.
