Rytz
Newly Registered
Posts: 1
Joined: Sun Jun 14, 2015 2:16 pm

Brown Discoloration on Lower Leaves of Basil

Hi everyone,

I just made an account on this forum in the hopes that some of you can help me diagnose the problem with my basil plant. There are brown areas on the lower leaves of my basil plants. The lower leaves seem to be the only ones affected (for now), but the discoloration seems to be slowly getting worse over time on these leaves. Here is a picture of my plant:
brown_basil.jpg

Some details about the plant:
- I started it from seed and transplanted it to this current container which is about 6''.
- The plant sprouted roughly 5 weeks ago.
- I have kept it indoors under a T5 light for ~15 hours per day (which I keep about 2 inches from the top of the plant). I live in an apartment with a patio that gets maybe 3 hours of direct sunlight per day, so outdoor gardening is out of the question, especially for the jalapeño plant I am attempting to grow as well.
- I water it only when I feel that the 1-2 inches of soil below the surface are getting dry (2, maybe 3 times a week)
- The soil medium is a mixture of 50% peat moss, 25% perlite, 25% vermiculite
- I mixed some "Miracle-Gro Shake 'n Feed Continuous Release Plant Food with Calcium for Tomatoes, Fruits, and Vegetables" into the soil around the time I transplanted the seedling into its current container.
- I examined the plant and the soil and don't see any visible bugs in the soil or on the leaves or under the leaves.
- The plant smells delicious and I can't wait to use it!

Does anyone have any ideas as to what could be the cause?

One thing that I feel I should disclose is that *ONE TIME* about 3 weeks ago, I mixed a very small amount of white vinegar into my water in order to help balance the pH of my tap water (The tap water in my city has a pH of about 9.0-9.4). The other basil plants I had died, but this one survived. I am leaning toward this not being the cause of discoloration, since the issue has seemed to get worse over time, even though I have just used plain tap water ever since.

Any help is appreciated--but please forgive the newbie mistake about the vinegar! :oops:

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rainbowgardener
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Posts: 25279
Joined: Sun Feb 15, 2009 6:04 pm
Location: TN/GA 7b

So other than the one time, you have been watering it with water with a pH of 9 ? ! (Wow, can you drink it?) Basil is more tolerant of a range of pH than many plants, but it prefers slightly acidic. "Basil will grow in a very wide pH range between 5.1 (strongly acidic) and 8.5 (alkaline) with a preferred range of 5.5 (strongly acidic) to 6.5 (mildly acidic)" https://herbgardening.com/growingbasil.h ... yyVdr.dpuf

So even with a wide range of what it will tolerate, you are outside that range. The effect of alkaline soil is to lock up nutrients, so they can't disperse through the soil and aren't available to the plant. Zinc, iron, copper, manganese and other micro nutrients become deficient. As a result, the plant shows visible signs of stress and injury across the leaf and stem structures. A sign of copper deficiency can be leaves and shoot tips that appear stunted and scorched.

Besides the spots, your plant is generally not looking entirely healthy, kind of droopy and stretched out. The stretched out (long internodal space) is likely that even with the best you can do, it isn't getting as much light as it would outdoors in full sun. It's possible the discoloration is a disease sign - plants that are stressed are also much more vulnerable to disease.

Honestly, if you just have a few plants to worry about, I would buy bottled water for them.



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