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Author Topic: Fertilizing during warm weather  (Read 18609 times)
helixturnhelix
Seattle, WA

Posts: 1945



« on: July 28, 2010, 05:07:54 PM »

Hi all,

I wanted to share some my experience with fertilizing during hot weather.  Something many of you in Southern California are missing out on this year Tongue  There are some sources out there that say that you should not fertilize during hot weather.  This is pretty silly not to give the plants fertilizer when they are growing the fastest, but as Charlie has said you need to be a bit careful when using fertilizers during hot weather.  When plants are taking up alot of water, due to increased evaporation and respiration associated with hot weather, fertilizing during every watering (even a small amount) can lead to fertilizer burn.  I experienced this first hand in early June, when the weather spiked into the high ninties.  I was using 2 tsp of HVH blend fertilizer per five gallons of water. This was a good fertilization regime when the temps were in the 70s and 80s, but when temps were in the high nineties I saw many of my plants starting to get fertilizer burn.  I stopped fertilizing and the fertilizer burn went away, but I still wanted to give my plants the nutrients they needed to bloom and grow well. 

Instead of changing my fertilizer use, I changed the time of day I watered.  Given that hibiscus use ALOT of water when temps are in the 90s-100s, I began watering with regular water in the morning.  (This water would be rapidly taken in as the temps increased, so it needed to not have any fertilizer in it.)  When the temps fell in the evening I would water again with my water + fertilizer mixture, when respiration and photosynthesis decreases tremendously.  The uptake of fertilizer occurs at a slower rate and the plant doesnt "overdose" on fertilizer.  After starting this regime I have not had any problems with fertilizer burn and have been getting all the benefits of fertilizing including great growth and tons of buds.  So to all my fellow hot summer growers out there, if you are getting fertilizer burn on your plants try this regime out!

Happy Growing Smiley

-Chris 
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Charlie
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« Reply #1 on: July 28, 2010, 08:13:23 PM »

Seems like excellent advice to me, Chris!  One question - when you water with plain water in the morning are you using enough to leach any unabsorbed fertilizer out of the pot?

Charlie
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helixturnhelix
Seattle, WA

Posts: 1945



« Reply #2 on: July 28, 2010, 08:56:06 PM »

Hi Charlie,

I just water enough to flow through the pot.  I have been watering alot lately and some minerals are getting leached out, I just treated with iron on monday.  Some of the plants looked a bit chlorotic.  Its amazing how fast they begin to turn green Smiley
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blupit007

Posts: 960



« Reply #3 on: July 29, 2010, 07:00:11 AM »

I am scheduled to fertilize today.  Last week I got fertilize burn on CH, so thanks for the heads up, I will try this tonight.  I was actually going to water just now, but decided to see if there was anything new going on here first.  Good thing.

Chris, when you say chlorotic, does that mean light green to maybe a touch of yellow?  I noticed one or two of mine looking like that and didn't know what to think.

Thanks
Kristen
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-Kristen
Charlie
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Posts: 3646



« Reply #4 on: July 29, 2010, 11:20:54 AM »

Chlorotic leaves are a common occurrence with hibiscus. The occasional one is nothing to worry about but if it starts to spread over a plant it indicates a problem with chlorophyl production. That problem is most often traced to a lack of one of the key nutrients that hibiscus use to make chlorophyl  - iron and magnesium being the most common that are lacking. The lack can come from too little available to the roots or can be due to root problems that stop them from absorbing these minerals. Too high or low pH is another possible cause. The easiest way to treat chlorosis is to add more chelated iron and/or more magnesium to the fertilizer water. In almost all cases this will green the plants up with visible results within 2 weeks. Faster but more temporary results can be had by spraying the iron and/or magnesium on the leaves rather than putting them in the soil.

Charlie
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blupit007

Posts: 960



« Reply #5 on: July 29, 2010, 09:29:18 PM »

Hi Charlie,

Is this Iron / Mag something that would be beneficial to use without signs of it lacking these minerals? 

I was worried about more spider mites on the few leaves that I see looking a touch spotty, but I'm super sensitive about those right now.  I look with the mag all the time and see nothing, so when I came across this post, I was just wondering if that is what it might be.

Thanks
Kristen
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-Kristen
Charlie
Administrator
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Posts: 3646



« Reply #6 on: July 30, 2010, 05:58:33 AM »

Hi Kristen,

Lots of people use iron and magnesium to give their plants a deep green appearance. I recall our friend David Wood writing that his neighbors in Vietnam are always remarking on the dark green leaves of his plants and wondering how he does it. His secret - chelated iron treatments. There are cheaper forms of iron, usually called elemental iron, but they are not absorbed well by hibiscus. Use the chelated form whenever possible. It can be used monthly for maintenance or weekly if there is a problem with leaf color.

The simple source for magnesium is epson salts. Despite the name these are actually magnesium sulphate and both magnesium and sulfur are needed and good for hibiscus. Mix a tablespoon of them into water with or without regular fertilizer and pour it into the root zone of your hibiscus. Do this once a month for maintenance or more often if there is a problem with leaf color.

Charlie
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blupit007

Posts: 960



« Reply #7 on: July 30, 2010, 06:44:20 AM »

OK great,

  I started with the epson salt last month on the first.  I didnt mix it in water, I just put some on the dirt around the root ball.  Where do I get chelated iron?  And how do I apply.  Sorry for all the questions... I know you are getting ready for tomorrow!  Have fun, I wish I didn't live across the country and could go to one!
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-Kristen
Doll

Posts: 1036


Houston, Texas


« Reply #8 on: July 30, 2010, 07:16:59 AM »

Kristen,
 You can buy some chelated iron right here from HVH:
http://www.hiddenvalleynaturearts.com/acatalog/minerals.htm

My Fat Actress I received yesterday looks like it might need some iron or is this just from being in a dark box for 4 days.
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I wasn't born in Texas, but I got here as fast as I could.
Charlie
Administrator
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Posts: 3646



« Reply #9 on: July 30, 2010, 08:06:30 AM »

I would give it iron because even if it does not have a lack of iron the extra iron will cause it to take on a darker green look. The leaves of Fat Actress are a lighter green than some others naturally but you can help determine the color by adding iron and magnesium.

One of the miticides we use can cause the leaves to lighten up, too. It's the mix of hot greenhouse temps and bright sun with pesticide that can do this. I figure mite free plants are the highest priority and the leaves will darken once the hibiscus settles in at the new location.

Charlie
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helixturnhelix
Seattle, WA

Posts: 1945



« Reply #10 on: July 30, 2010, 08:23:54 AM »

Iron dosing works fast too, i dosed on tuesday and look at dark green near the leaf veins! Its cool how it spread from the source of iron, Smiley


* photo.jpg (132.51 KB, 600x800 - viewed 511 times.)
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blupit007

Posts: 960



« Reply #11 on: July 30, 2010, 10:28:25 AM »

Thanks Doll, I should have know!
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-Kristen
Charlie
Administrator
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Posts: 3646



« Reply #12 on: July 30, 2010, 01:31:22 PM »

What a great illustration, Doll! 

Charlie
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