I bought these mums less than a month ago and planted them in Miracle Grow Potting Soil. Kept them in sun for 3-4 hours and in shade for the rest. They were left in sun for a couple of days at around 90 degree F. After watering them in the evenings they appeared to recover. After a while, I saw white powdery substance on the leaves and assuming it was some kind of fungi, I sprayed Neem Oil and water mix. The powdery substance disappeared but soon all flowers turned brown and I thought that happened cause of hot temperatures. But the leaves would never feel as fresh as when I bought them. Then I noticed all flower buds browning and falling and brown spots showing up on the leaves. I also noticed small white larvae (4 in number) feeding from the plant stems and then they'd disappear below the leaves. I removed all of them and since then I have not seen any.

I have other plants too (Mint, Basil, Other Mums) potted in the same soil which seem healthy for now.

Is there anything that can be done to save this plant or should I discard this plant and the soil to prevent the infection (if any) form spreading ?

P.S - The plants are located in Seattle, WA, USA area. This year the summer has been rather brief.

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  • While I do see a little leaf minor damage, I see more of what looks like thrip damage. Oct 4, 2022 at 10:30

1 Answer 1


Were these mums out of doors when you bought them or inside the store? If they were indoor plants they would be experiencing some shock being introduced to the sun without acclimatization.

Spraying Neem on the flowers could account for burning the flowers. Is this soil just Miracle Grow, nothing mixed into the soil? Miracle Grow potting soil comes with fertilizer usually. Check this and do not add any fertilizer if it does.

You do have Leaf Miners. This would be a good reason to spray with Neem otherwise without an ID of a pest or problem don't use pesticide.

Spray at night not during the day when pollinators are out. Lay the plant on newspaper and spray the undersides of the leaves as well, some on the top of the soil. Then a second application one week later. Cut off wilted and old leaves, that would help to open your plant for more aeration. Don't spray open flowers.

When you cut flowers and leaves off cut all the way down to the host stem so you don't leave 'stumps'. Cutting off flowers as soon as they start deteriorating helps the plant grow better leaves, stems and many more flowers.

  • Thanks @stormy. These mums were outdoors but not at a place they'd receive any direct sunlight. The soil is only Miracle Grow nothing else has been added to the soil. I have been spraying neem always in the night and I will try spraying the undersides as well. As a quirk i sprayed the neem directly on the larvae and observed if they died, but nothing happend and they were still moving around in my petri dish after a long time. Can this problem spread to other plants ? Shall i quarantine this plan ? Aug 9, 2019 at 20:39
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    Insects die a slow death. I hate the smell of Neem. Check your bag of Miracle Grow because they seem to always add fertilizer.
    – stormy
    Aug 10, 2019 at 21:58
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    You did this in a Petri dish??? I love you!! Leaf miners are already in your environment or this plant already had them before you brought it home. Love it that you tested this in a petri dish. You ARE a gardener. Grins!! Under a roof yet out of doors is great for plants. If you want to grow veggies or have lots of flowers, not so much. I love foliage. I have two greenhouses a grow room but NOTHING gets planted in the environment I live in OUT OF DOORS. Sad
    – stormy
    Aug 10, 2019 at 22:05
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    btw, I KNOW the Seattle and Eastside very very well. Most of my projects and work are there. I miss Duvall and Carnation (Tolt). I now live in south central Oregon and why oh why didn't I check this zone before moving??
    – stormy
    Aug 10, 2019 at 22:08
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    And yes, I would tend to 'quarantine' this plant. Look at your other plants to see if you've got leaf miners? Little squiggly white lines? Leaf miners are never a disaster for plants just aesthetic. Still haven't tried to up load this pictures...
    – stormy
    Aug 10, 2019 at 22:13

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