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I live in Redwood City, Bay Area California (From wiki -Redwood City, along with most of the Bay Area, enjoys a mild Mediterranean climate, with warm, dry summers and cool, relatively wet winters.) and we have a morning glory in a potted container. We have had it from last summer. This summer it has developed brown spots on its leaves and some of the leaves are also yellowing. The brown spots are on both yellow and green leaves. I did some research but does not look like it is a insect problem. We have been watering it consistently allowing the soil to dry out.

My only suspicious is that the last week has been extremely hot 80-90 F so could it just be too much sun. enter image description here

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  • Where's Redwood City? Many members here at SE are from countries other than the US.
    – Jude
    Jun 22, 2017 at 18:05
  • Good point. Edited the question.
    – Manny
    Jun 23, 2017 at 15:59

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Morning glories love sun and even high temperatures shouldn't cause the damage shown.

Have you added new soil or compost to the planter? Any slow release fertilizers? How regularly have you watered the soil in the planter? Not on a strict schedule but to make certain it's neither too dry nor not too wet.

Start by thoroughly cleaning up your planter, removing all dying and dead parts. By leaving it as you have, you're allowing any viral or fungal disease to continue spreading. If it's cultural mismanagement instead, you're still inviting fungal diseases to develop in the dead plant matter, especially if it gets wet.

Dig out the worse affected plant to check on the roots (or tuber depending on what species morning glory you have). Look for signs of root rot or black canker, if it's a tuber. If you find it present and if the soil hasn't been soggy through the winer and spring, it may be a fungal disease that attacks the roots. I've never found morning glories to be troubled by pests or diseases but I've only grown them as annuals.

If you haven't amended the soil since last year, do so and add a slow release fertilizer mixed in. Since I can only see part of the planter, I don't know its size. Using the same soil mix year after year without replenishing the soil is always bad practice. Since I can't examine your plants or soil mix, I can't say for certainty what the cause is. But I'm leaning toward depleted soil and/or inconsistent watering.

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  • Thanks a lot Jude for your reply. We haven't fertilized it much because I had read morning glories prefer poor soil. We haven't added any soil or compost. I will change soil and report back . > If you find it present and if the soil hasn't been soggy through the winer and spring, it may be a fungal disease that attacks the roots. Should the soil be soggy in winters? Shouldn't you water it less in winters? Thanks!
    – Manny
    Jun 24, 2017 at 0:38
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    The idea of poor soil being better for flowers comes from the idea that fertilized or well rotted manure enriched soils were higher in nitrogen and promoted leafy growth at the expense of flowers. But a well balanced fertilizer (the ratio of N-P-K being equal) won't do that. It'll still give you lots of flowers while the entire plant continues to grow strong. I like stormy's suggestion of slow release coated fertilizer mixed in soil. Don't use those awful 'more bloom' fertilizers with a very high middle number (phosphorus) and low nitrogen and potassium. It's hard on plants.
    – Jude
    Jun 24, 2017 at 1:07
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    No, you DON'T want the soil to stay overly wet through winter. I meant if it had stayed wet, you'd expect the roots to rot. But if the soil was rained on and dried out well periodically but you found dark or grey rot, the cause was likely a fungal disease instead of simply rot from being waterlogged. I hope that's clearer now.
    – Jude
    Jun 24, 2017 at 1:12

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