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Question and Answer Page 2


growing seasons
desired ppm for tomato plants
12 volt timer
ppm control
successful way to clone
make my own solution
seeds grow the best hydroponically

Watering to often? JB
I have a system that I designed that is a cross between an ebb & flow and a NFT system.
The plants are grown in 4" rockwool blocks, and there is a 1/8" of nutrient film that runs along the bottom of the blocks every 15 minutes, for fifteen minutes.
My question is:
Am I watering the blocks/plants too often?
They seem to be growing healthy but they are a shade lighter green that plants that I am used to growing in soil. Although they are a lighter green, they do not appear to be pale.

To JB re: Overwatering
Hi JB - I have used rockwool quite a bit - in block, slab and flock (granular) form. The best results
were obtained using blocks transplanted (placed on top) of slabs using a drip setup (see slab system member's garden). Also worked really well in ebb & flow in 3 and 4" blocks. And, of course, in aeroponic and nft systems the seedling (or cutting) started in smaller rockwool cubes. The aeration factor of rockwool is good but not as good as aggregate (Leca) and other media. If using blocks and the bottom of the blocks are in full contact with the growing container you may have not so much of an over- watering problem as an aeration problem. I would need more particulars on your system to be able to make an educated guess (which is what I do!) on the problem. Also, what nutrient are you using? If the plants are growing at a fairly normal rate and the leaves look good (shape, edges, etc) then your nutrient may be at least part of the problem. There may not be enough of the "right form" of nitrogen to keep the plants a darker green. I've found that most "grow" nutrients formulated for hydroponics work well for most plants. I hope these comments help. If you need more info give more particulars on your system and nutrient and I would be happy to comment again.
Ron K.

What are the growing seasons here in the St. Petersburg area of Florida.
Is there a stop growing for the months of June, July, August?
My hydroponic garden is in a screened in area with no control of summer temp.or humidity. Thanks

Yes it is standard practice to close down the hottest months of the year and use that time to clean
your equipment and make any changes that need to be made.
Tomatoes produce the largest yields when day temperatures are in the range of 80 to 85
degrees F, and when night temperatures remain between 62 and 72 degrees F.
I can grow tomatoes up to august by using 70 percent shade cloth.

Could you please tell me how to find ppm. Please tell me all the formulas, and other information you have.
Also could you please tell me the desired ppm for tomato plants(Indoor).

From Ron
: Two recent tomato projects (one indoors the other outside)indicated that tomatoes love a great
deal of light - especially from blossoming stage on - and an increase in TDS of minerals to the fruiting stage.
I found that increasing TDS gradually from 500ppm as seedlings to 1500ppm or more during active
fruiting stages works very well.
Full sun for the entire daylight hours is also very important.
The outdoor project pictured in Ron Kleinman's garden (A & B) were full sized tomato plants with
full Southern exposure (rockwool slab drip system).
TDS was maintained between 1500 and 1800ppm using a two part bloom formula.

Hi Ron
We put together a hydro unit several weeks ago using 4” PVC pipes 5’ long with small gravel.
The unit is at the back of the property and I didn't want to run AC wiring through the back yard. We have utilized a 12 volt motorcycle battery, bilge pump w/ float switch shutoff, a small solar panes to recharge the battery.
The only thing missing is a 12 volt timer to automate the watering cycles any Ideas?
I also am just completing your 11 plant garden and want to hook it to the same 12 volt system. By the way Zucchini Squash grows extremely well in hydroponic’s the plants stay reasonably small with a huge yield.
Will send pictures within the next couple of weeks.

I have had the same thought about your battery powered garden.
Some yard watering timers run on a lower voltage and might be modified to work.
If anyone knows of a battery powered timer please let us know.

Re: 12v timer:
I am an electrical by trade and researched the equipment available for remote 12vdc applications.
It's possible that I missed something but I spent lots of time and searched a bunch of catalogs.
For around a hundred dollars you can get either a programmable cycle timer or programmable multi-setting timer. These are normally panel mounted units. My idea was to install a photocell - to shutdown the system at night - then use the cycle timer to set the feed evolution. It could get a bit complicated.
By the time everything was figured it was just about as expensive (and I would get higher capacity equipment) to install a small 12VDC to 120VAC inverter an regular digital timer and a good Pro or Little Giant submersible pump. Also, a deep-cycle, higher capacity RV or boat battery will probably give better service.
Sorry guys, I don't mean to burst any bubbles (like mine was!) but there ain't any way I can figure to get off cheap on this one.

To Ron K.
The nutrients that I am using are a commercial mix that I bought recently. I checked the ppm on nitrogen and found it to be low, so I am assuming that was the "lighter green" problem. The mix is based on calcium nitrate, potassium nitrate, and micronutrients. It is high in potassium, med - high in nitrogen and medium in phosphorus. I have since adjusted accordingly.
The system I use has the rockwool blocks on a tray that is slightly wider than the blocks themselves.
About of the block is actually touching the water when the pump is on. The other half is suspended over the bottom of the container. With no better way to explain it, the rockwool is corrugated. only some of it touches the nutrient solution.
The roots are a nice white, so I think aeration is not too much of a problem. The pump cycles for 15 minutes on 15 minute cycles.
This is my first attempt at an actual hydroponics garden. I have made previous attempts with complete failure. I have been growing vegetables in the ground and soil for years and I have to say that my plants are the fastest growing and the healthiest <sp?> plants I have ever seen. I just may stick with this hydro thing ;-)
One more question. Because I am a little low on nitrogen, could I adjust my pH up with ammonium hydroxide <household ammonia> I do not want to use potassium hydroxide as I am afraid that it will raise the ppm of potassium in the solution too high. Can I expect precipitation of some of the constituents if I use ammonia? I would really like to give it a try but I don't want to screw up the first successful hydro garden I have had. Thanks

To JB,
Sounds like you have the nutrient solution pretty well under control. Actually, a bit of Ammonia (use VERY sparingly) will help green-up your plants fast. Since you use mainly the nitrate Nitrogen (as should be) a little ammonium won't hurt. Ammonium (ammoniac nitrogen) is absorbed by the plant almost immediately in hydroponic applications because there are no micro organisms to hold it "in check" (slow it down) as in soil. It can do a very quick green job but too much will cause "leggy"
I would stick to Potassium Hydroxide or calcium oxide for adjusting pH up and Nitric, Phosphoric or citric acid for pH down. in the case of Potassium Hydroxide, since so little is used for pH correction, the addition is so small that only a negligible amount of potassium will be added. All this is basically a repeat of what the folks at the Eco nutrient facility have explained to me.
Ron K

To JB:
Just talked to John McNinch who is a "real" expert on plant (hydroponic or soil) nutrition! His put is that you can use ammonium hydroxide for pH up but be very attentive - he recommends not exceeding 25% total ammonium as the nitrogen source. Also, to help insure hydroponic success it is a very good idea to change the nutrient solution every two to three weeks - this will reduce the possibility of feeding an unbalanced nutrient solution to your plants.
Additionally, I recommend that you watch TDS and do not exceed 500 for seedlings and 1500 - 1800 for heaviest fruiting stage of growth (tomatoes, cucumbers, etc.). This is the range that has worked best for me although others have used higher TDS applications successfully. Hope this helps.
Ron K.

What is the simplest most successful way to clone?

First I pick how many inserts per tray I will use and that will depend on the size of the clones.
Fill the tray up with vermiculite.
Mix up at least 1 gallon of cloning solution per tray.
I use Olivia's Cloning Solution but you can use any good solution that is formulated for cloning.
Formula One works for cloning in low dosages
Soak the vermiculite with the gallon of solution.
Poke a hole with a nail or pencil for each sucker clone in the vermiculite.
Wear latex gloves because plants don't like to be touched by human hands..
Use a clean razor blade and change it often to cut down on transferring diseases from plant to plant.
Cut the sucker at a 45 degree angle and stick it about 2/3rds the way down the vermiculite.
Cover with a plastic hood to bring up the humidity.
You can make a hood with wire and plastic food wrap.
Place under Cool White florescence lights and in 7 to 10 days or when you see roots they will be ready for transplanting to your garden.

Could someone please tell me the recommended ppm of each nutrient for a standard tomato solution. I have had the hardest time finding these numbers. I plan to make my own solution and this information is necessary. If anyone answers this they will be immensely helpful. Please keep in mind that it is the formula I want, not how to find ppm or the total ppm.
Mathieu Loiselle
P.S. Does urea nitrogen eventually get absorbed and used by the plant?

Tomato Nutrient Formulae Click here.

Re: Mathieu L. 4/30:
Mathieu, I really don't mean to sound critical but I speak from experience of trying the same thing you are trying - to formulate my own nutrients. I found out that it was more expensive and time consuming than using already proven hydroponic nutrients. I recommend using proven hydroponic formulations in one system at first and experimenting with your own formulations in a separate system.
There's an excellent book by Howard Rush that gives a detailed report on the nutrient formulations for tomato plants. The name of the book is: Hydroponic Tomatoes For the home gardener and it only costs about $10. There is also another book by Ed Muckle: "Hydroponic Nutrients - Easy ways to make your own" that details several nutrient formulations. And, of course, the Granddaddy of all hydroponic reference manuals: "Hydroponic Food Production" also by Howard Resh that is the industry standard.
Just to give you an idea of the nutrients required for Tomatoes: First of all, Resh recommends a 3 separate formulas for the three basic growth stages: Grow, Bloom and heavy fruiting. All the formulas contain these minerals in avaying amounts: Macro Elements: Calcium Nitrate, Potassium Nitrate, Monopotassium Phosphate, Potassium Sulfate, Magnesium Sulfate Micro (trace) Elements: Boric Acid, Manganese Sulfate, Coper Sulfate, Zinc Sulfate, Sodium Molybdate, Iron Chalet (10%
So, you see, a proper nutrient formulation is more involved than first imagined.
As for Urea: No, it is generally not used by hydroponicly grown plants unless the water contains the enzyme "urease" which is present in soil to convert urea to ammonium ions that the plant can assimulate. So, in soil urea is eventually used. About the only way for the enzyme urease to be present in hydroponics is if it is added to the water somehow - either by containing large amounts of algae or has had other biological activity. I hope all this info helps.
Ron K.


In my book Gardening at a Glance by Tanya Denckla she recommends a pH of between 5.5 to 7.0 for Sweet Basil.

Hi Ron,
I am new to hydroponics and have learned a lot from the questions and answers posted here.
I would like to know what varieties of seeds grow the best hydroponically for tomatoes, peppers, cucumbers and other common veggies.
Thanks Paulette

Hi Paulette
They do have seeds bread just for hydroponics, mostly from Europe
You can try Hydro-Gardens, Inc. (800) 634-6362
I would use a verity that grow well in your area.
Ask your local nursery they will know what kind.


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