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yellowing leaves

Posted by kea2 (My Page) on
Wed, Oct 17, 07 at 3:25

The lower leaves on my basil are turning yellow - almost white, actually - and going brown on the edges. Eventually, they drop off. I converted this basil plant from potting soil about a month and a half ago. I kept it out of direct sunlight, with a clear bag over it, with no fertilizer for about 3 and a half weeks. It lost a bunch of its lower leaves in the process and then stabilized. Now that I've moved it outside, it's going yellow again. It also doesn't seem to be growing.

I can't figure out if I should stop giving it fertilizer or start giving it more. I've only been giving it 1/4 - 1/2 strength hydroponic nutrient solution.


Follow-Up Postings:

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RE: yellowing leaves

I've got no experience with basil. Never grew it. But I checked with some friends and consulted some sites on the internet:
All I can find is that basil is susceptible to aphids. It is also reported that basil likes LOTS of water and can take full sunshine. Unfortunately, there is nothing that descibes your problem specifically to basil,

So - I suppose - the answer has to be that your basil plant's rootsystems are either underdevelopped or that the plants can't get enough moisture.

My suggestion is that you should - first of all - ensure that the roots always touch the top of the nutrient solution by about inch, and - secondly - keep the plants indoor and feed it full strength nutrients untill the plants starts to grow normally. Then, start moving the plants outside.


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RE: yellowing leaves

I shall move the plant back into the shade until it starts to grow. Maybe it does need to grow more roots. The bottle of nutrient solution says to apply it once every 7-10 days, but my reservoir (OK, it's a deep saucer) only lasts about 3 days. Would it hurt to keep topping it up with more full-strength nutrient solution?


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RE: yellowing leaves

I think that's fine. Just make sure the roots touch the nutrient. Check that every day!


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RE: yellowing leaves

On the plus side, my cuttings are doing fine now, and growing quickly too. They've sent a huge wad of roots down into the nutrient solution. They also keep trying to flower. Now I just have to wait until they're big enough to eat.


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RE: yellowing leaves

Enjoy it! smile


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RE: yellowing leaves

What is your system for this basil? What type of media? What type of nutrient?

I kinda sounded like it is a flower pot on a deep saucer with some form of soil-less media in the flower pot supporting your basil plant. If this is the case your plant could be suffering from a few different things.
1-It might not be able to reach the nutrient very well and is drying out. This probably isn't the case since you say it is only the lower leaves showing problem.
2-Too much water could be evaporating leaving the nurtient too strong and burning the plant roots.
3-If the nutrient is plenty deep enough that much of the roots are submerged the problem could be more to do with lack of aeration of the nutrient solution.
4-salt build up in the media could be a problem.
5-The bottle of nutrient, is it specifically for hydroponics? If not, you plant may be suffering from a nitrogen deficiency because the nitrogen source in most fertilizers requires soil microbes to turn the urea or amonia based nitrogen into nitrate nitrogen for the plants to use.

Some simple things you can try and see if they help include,
use some plain water to flush out any excess salts that might have built up. Decrease the strength of the nutrient and see if the plant perks up if not, you can try increasing the strength but be careful not to burn your plant. Basil is kinda a light feeder in hydroponics so full strength nutrient is probably not necessary. First you might want to make sure that your nutrient solution is actually hydroponic nutrient and not something like Miracle Grow. (Miracle Grow and the like can be made to work for Hydroponics but you have to add something like calcium nitrate to it or your plants may have problems with nitrogen deficiency. One of the signs of such a deficiency is yellowing older leaves though there are several situations that can cause that, not just a lack of usable nitrogen.

Good luck. It is good to hear about your cuttings doing well.


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RE: yellowing leaves

Thanks for your reply! Let's see. It is in a 5 inch regular flowerpot in a saucer that's about 1/2 inch deep. It's growing in small expanded clay pellets (approx 1/4 inch diameter), that were advertised as orchid growing medium. The nutrient solution I use does say it's for hydroponics.

I don't think it's number 1 because the plant never goes limp. It seems to be drawing up enough moisture.

It could be 2 or 4. The nutrient evaporate quickly and is usually gone within 2 or 3 days. Even if I put it in at 1/2 or 1/4 strength, it might end up too strong towards the end. I've already tried flushing it a couple of times, but it didn't seem to help. I may be able to remedy this by getting a bucket to serve the outer pot/reservoir, which would reduce evaporation.

It could be 3. How can I improve aeration? Should I switch it to a larger size clay pellet which would leave more space for air between them? Drill holes in the sides of the pot? It could also be that the pot's too small, but I thought that was less of a problem in hydroponics.


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RE: yellowing leaves

It is actually kind of a myth that plants in hydroponics don't need as much space as plants not in hydroponics. The plants my not need to extend their roots in search of what they need but the roots still need space.

I would keep the solution weak or you can simply add plain water between nutrient feedings which will help dilute the solution back down if you feed stronger solution. A deeper bowl or bucket will probably help.

As to the aeration, it isn't about the size of the clay pellets. It is more to do with the stagnant solution that the plant is sitting in. Some plants do better than others in such a situation. Most larger hydroponic systems have some sort of bubblers or pumps that aerate or circulate the nutrient solution which keeps it from getting stagnant. For your set up simply stirring or blowing bubbles with a straw into the solution once a day might make a difference. This is assuming you don't want to get an aquarium air pump and air stone to keep in the dish your plant pot is sitting in.

Is the plant looking really bad or is it just loosing a few lower leaves? I've had basil plants get rather large (out in a 3 gallon pot or even in soil) and looking pretty healty but I think they lost older/lower leaves too. We got one basil out there that looks a bit more like a bush than a herb but we let that go to seed and it probably won't survive much longer as I think it has been going for about a year now.


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RE: yellowing leaves

I've moved it to a large pot, and I'll try blowing bubbles into the solution every day. Thanks for the tip. It does look pretty bad - it's already lost all the leaves on the bottom half, and they're still getting pale. Any more and it'll look like a palm tree. I'm giving it half strength solution, and I'll top it up with water when it starts to get low.


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RE: yellowing leaves

How is your basil doing now?


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RE: yellowing leaves

I'm seeing lots of strong root growth, but little in the way of new leaves. It's also lost a couple more.


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RE: yellowing leaves

could be lacking in nitogen with the available nitrogen going to the newer growth


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RE: yellowing leaves

check the ph in the water your using make sure its between 5 and 6.5 also make suere the plant is getting enough light also the roots should be completly dark if you've already flushed the system with clean water(no solution)then make sure the roots aren't sitting in stagnent water try using a wick from the solution to the roots check for bugs and if indoors make sure humidity isn't too high


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RE: yellowing leaves

It's been about six months. He's probably either fixed the problem by now or it's dead.


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