Ask Erik

I have a set up of tomato plants on an ebb and flow system. I started having problems two to three weeks in to veg state. The leaves started curling under and leaves started to get spots on them. I immediately thought it was a nitrogen overdose but the only thing I was giving them at that point was B1 at 650 PPM. So I flushed the system over night and they still have stayed the same. I am starting to wonder what the hell the problem is. What should I do? Flush some more or add a PPM of more nitrogen. Either way how long will it take for the plant to respond?

The symptoms you describe are characteristic of salt build up. However, if I understand correctly, your nutrient solution with B1 is about 650 ppm. If this is the case, toxicity is an unlikely scenario if your plants are two to three weeks into veg. and are receiving adequate light, ventilation, temperature, pH, etc. The curling under and spots sound a lot like a potassium deficiency. I am not sure what type of food you are using, so I can’t really say which part you need to add more of.
You can try adding about one teaspoon (seven grams) of Potassium Sulfate per 4 U.S. gallons (3.785L per US gallon) of nutrient solution. This should provide about 200 ppm of K (potassium). If you have difficulty obtaining Potassium Sulfate, you can get potassium nitrate (salt peter) at just about any drug store. Add at a rate of one teaspoon per three U.S. gallons of nutrient to get around 200 ppm of K. As potassium nitrate also contains nitrogen (13%), it will supply about an additional 70 ppm of nitrogen, which shouldn’t be excessive due to your relatively low feed strength. To attempt to relieve the condition more quickly, you can use the above rates and apply either potassium sulfate or potassium nitrate as a foliar spray, but make sure that you also increase the amount of potassium available to the plant at the roots. Additions of high quality fulvic acid in the veg. stage will help to improve nutrient absorption, mobility, and can be added to sprays to increase their effectiveness.
Alternatively, if it’s not a potassium deficiency, it could be that your plants are receiving too much moisture, as spots and occasionally leaf curl can be a symptom of overwatering. Inspect or test the root system for disease. Damaged plant tissue will not likely recover, so make sure the plants show signs of healthy new growth before initiating the flowering cycle. As an estimate, in hydroponics you should see some change in the plants within 48 hours of any change in feeding. In soil, it could take days or even weeks. Sometimes after applying foliar sprays, and change can be seen in hours, depending on the nature of the problem.
Cheers, Erik Biksa

Hi,
Wondering if you might know of some sources for Giberellic Acid and some more detailed information about it. Also I am trying to find out some information on something called Colchicine used in seed propagation ... do you know what I am refering to? I would greatly appreciate any help. Thanks much.
Ken Erdmanis, California

Ken,
Thanks for your questions. It’s always a good idea to research any chemicals you are considering using. No matter how you spell it, colchicine is a very poisonous substance and I don’t recommend experimentation with it outside of a laboratory setting. Colchicine has been used to induce polyploidy in several types of plants from forest seedlings to orchids. I have heard some information (although sketchy) that some popular strains have polyploidy parents in their lineage. Also, some commercial orange tree varieties are rumoured to be polyploidy. Basically most plants have two sets of chromosomes (2n). Polyploidy plants are different in that they have several sets of chromosomes, more commonly expressed as (4n). The resulting plants are mutants, which can offer magnified desirable traits such as increases in size, weight, and vigour among others. Polyploid plants may appear quite different from their diploid counterparts in that they may have odd shaped stems (i.e square) and have many more blades per leaf (i.e. 14 instead of seven). Naturally occurring colchicine can be found in the bulbs of autumn crocuses. Exposing seeds to a carefully prepared (heavy gloves, etc) one part mashed bulb to three parts water solution will reportedly kill all but a few seeds out of 1000. The resulting seedlings may exhibit polyploidy. If a lot of the seeds survive, the concentration was likely not high enough to induce polyploidy. The colochine treated plants should not be consumed, as they would likely be highly poisonous. The polyploid plants can serve in a breeding program or as mother plants. You should not consider applying colchicine as a spray. Again, I cannot over-emphasize just how toxic colochine is and DO NOT RECOMMEND that anyone outside of a professional laboratory experiments with it.

I am writing to ask your advice on growing Alpine Strawberries with a hydroponic system. I am doing this as part of a high school class. I have just been introduced to hydroponics and I am hoping you can give me some advice on what type of system togrow these strawberries in. If you can give me any info or point me in the direction of someone who can it would be greatly appreciated.
Thanks, Josh

Josh,
Thanks for taking the time to write. Strawberries are among the many crops that are commercially grown using hydroponic growing methods. Alpine strawberries are similar to the “domesticated” strawberries more commonly grown, although producing smaller fruits, they are very hardy, can be grown from seed, produce no runners, and are ever-bearing (day neutral).
If this is for a high school project, I will assume that you would like to keep your budget for materials, etc. to a minimum. Strawberries prefer well-drained growing mediums and the roots must be protected from heat. Special care must be taken to ensure that nitrogen is not over applied as it will diminish the quality and overall number of fruits produced. For your situation, I think that growing in perlite will work best. Perlite is a light weight, inert growing medium produced from a type of silicate treated at very high temperatures, and will hold three to five times it’s weight in water. Perlite can be obtained very inexpensively at any garden center or even some supermarkets in the plant care aisle. Perlite can compact, reducing porosity, but this shouldn’t be a concern in the case of growing smaller plants such as Alpine Strawberries. Your system can be as simple as filling some one gallon pots with perlite and hand watering with a full-spectrum, balanced hydroponic nutrient solution (while maintaining the correct pH and TDS). For an inexpensive automated system you could drill a series of holes in the bottom of a shallow Rubbermaid container (37.9L) before filling it with perlite. You may also drill in a larger hole and vertically insert a large diameter pipe (2-3”) that will help facilitate checking, filling, and draining the solution in the lower vessel while plants are being grown in the upper vessel. Then, place the shallower container into the same sized, but deeper Rubbermaid bin (52.9L) which will act as a lower reservoir. Within the lower reservoir place several aquarium airstones connected to an aquarium air-pump (running continuously to provide aeration). When starting new plants, allow the depth of the solution in the lower reservoir to touch the bottom of the shallower top container supporting the plants. This will allow moisture to wick-up through the growing medium. Once the plants have become established lower the depth of the solution of the lower container so that there is a couple of inches of air space between the upper and lower vessels, as the bare roots will begin to grow into the aerated solution. Algae may develop on the surface of the medium, but can be avoided by simply covering the perlite with grow rocks or aquarium gravel.
Keep the plants in a warm, brightly lit area. As ever-bearing fruits, Alpine strawberries can be subjected to 24 hours lighting to saturate photosynthesis. As they are low-profile plants, you can light the bins with fluorescent lighting. The fixture(s) should be on a chain so you can adjust the distance from the lamps to the plants. As fluorescent lighting diminishes with distance traveled, it is recommended that you keep the lights just a few inches away from established plants.
Always use the best quality water available to you for hydroponics. As an experiment, you might use tap water in mixing nutrients for one batch of plants, and distilled water for another. Hydroponic nutrients are available through many retail hydroponic outlets and the internet. Look for ones that allow some flexibility in addressing the nutritional requirements of the plants, you will want to be using a low nitrogen, medium phosphorous, high potassium formulation. Make sure that it contains calcium, magnesium and chelated trace elements such as iron. Keep your solution depth topped up with fresh water. After having replaced one half the reservoir volume with fresh water it is time to drain the system and fill with a fresh batch of nutrients. Maintain the temperature of the solution between 65-70°F. Liquid pH test kits are inexpensive and accurate for your purposes. If you can’t afford a dissolved solids tester (TDS) for measuring the strength of the solution, make sure that the fertilizer you are using states the concentration of resulting solutions following their written mixing rates.
Good luck, and make sure to take lots of pictures while keeping accurate notes.
Sincerely,
Erik Biksa