Trying to grow basil cuttling using the Kratky method: plant is flappy and has brown, brittle roots

[ionnabli]

What am I doing wrong? The plant is still at the beginning so the water level is high and it doesn't have air roots yet because the part of the stem that is growing roots is fully submerged.

Today, it became flappy too as if it was thirsty. And the roots are turning brown and brittle.

Would appreciate any advice

[imafan26]

Brown roots are a bad sign of the water having too much bacterial or fungal contamination. I know you can start seeds in a hydroponic set up, but it usually isn't done for practical reasons. Most people start seeds in trays conventionally and transplant them into the hydroponic set up to maximize the cycling and minimize the cost of the hydroponic solution.

I don't know of anyone who has used cuttings in a hydroponic set up. Cuttings have some issues. One, especially with basil, you would not know if the cutting is clean. When you make a wound your tools must be very clean or you could introduce contaminants or fungi or bacteria can find a way into the plant through the wound. Hydroponic systems work best with young actively growing plants, not older ones.

I am pretty sure basil is not a bog plant. While you can root basil in water. I won't thrive without oxygen. I think because all of the roots are submerged and the media is also saturated, the roots are dying because they are not getting oxygen. When you do a hydroponic set up, you need a seedling with a heathy root mass. When you place it in a net pot, only about 1/4 inch of the bottom of the plug is touches the solution and water wicks up the plug. The roots at the top of the plug and especially the roots growing on the outer parts of the plug will have access to oxygen. If your cutting was entirely submerged in the hydroponic solution, eventually it will die from fungal rot because it needs air roots.

[pepperhead212]

I agree with imafan about the basil needing more oxygen; in fact, I think most plants need more oxygen than provided in the Kratky method, which is why I am not a fan of it. I grow basil from cuttings all the time in deepwater hydroponics, with not only an airstone in each tub, but a small powerhead, with a sponge attached. And when rooting cuttings, I dip them in an H2O2 solution initally, to sterilize them, before rooting. Sometimes, when rooting a lot of cuttings, I do it in a cloner, but when doing just a couple, I do it in the DW, just dunking the cutting in rooting gel, then put it in the basket, with ceramic pellets around it, and it roots fast. Here's a good example, showing a bunch of basil started from cuttings, compared to a couple started from seeds the same day. The epazote grew even faster!
Hydroponics, 10-11 by pepperhead212, on Flickr

And here's what the roots should look like, on the basil:
The roots of one of the basil plants in the hydroponics. by pepperhead212, on Flickr

[imafan26]

Aerators are optional in a Kratky system. The idea of Kratky is to be able to have a system that does not require power. I have read and heard that Kratky does work better with an aerator and there are fewer issues with mosquitoes as well.

In any hydroponic system, keeping the system clean is very important. If you have pests or disease, it will propagate in the system and will be costly to have to dump everything, sanitize the system and start over. It is why you bleach the system usually after each cycle to kill off algae and any bacteria or fungi that may be contaminants in the water. For the same reason you would also use clean media. If you use a biofilter, eventually, it has to be cleaned. Potting soil, oasis blocks are usually only a one time use and would not be reused. If there are problems with some seeds like cabbages, people will get certified seeds to make sure they are not going to introduce diseases into their system.

[ionnabli]

Thank you both. I will try again from seed.

Any tips for starting the seeds with cotton? I don’t have any of the fancy cubes at hand and would rather keep the investment minimal while I’m assessing the viability of Kratky at home.

[pepperhead212]

When I start basil seeds for hydroponics, I start them in small jiffy pellets, or the even smaller coir pellets (Ferry Morse, I think?), which are both good for lettuce and brassicas, as well.

[imafan26]

The garden just uses a 72 plug tray and potting soil. The soil does get in the water, and could be a problem if there was a pump, but if the root ball is well established, most of it will stay together.