I germinated my seeds (2) in wool blocks. They sprouted in about 4 days but have long stems. one is at 3" and the other 2" and both have one set of true leaves. There is one root coming out of the bottom of the wool block. I’m thinking I didn’t plant them deep enough into the hole and that is why they are so tall. Should I put the wool cube into potting soil and into a larger pot. I have them growing under a florescent light that is on 24/7. They are now 2 weeks old. Any info greatly appreciated. I have not grown for many years and the wool cube is new to me.
No, it has little to do with how deep you planted them. If the light is not intense enough the plants can stretch and become very stringy and not capable of supporting themselves. Also a light breeze from a fan will help the plant develop rigidity in the stems.
Thanks, Do you think I can salvage them? I will try the fan. Should I transfer the wool cube to soil and plant them deeper?
You never plant any plant deeper. Yes, it is possible to keep these going. You need your light 1-2" from the tops.
Yes; If you see the tap root; you should pot the plant in a small pot. 4"-1gallon. do not apply nutrients.
Thank you. I will plant them (with the wool cube) into 4" pot. They will then be about 2" from the light. Will go by a small fan also. I was sold a tray with a 8" dome lid which I guess kept the light too far from the plants…
Actually you can plant the plant deeper. Some do not recommend it because in some instances it might contribute to “stem rot”, but if you are using clean fresh coco coir or hydroton or even good soil, often lots of people do bury the seedling a little deeper to shorten the sprout with no ill effects…
If you are using Coco or Hydroton; You are planting below soil. There is plenty of oxygen available using these mediums. If you plant Rockwool cube below the surface you are risking too much dampness at the stem, and are asking for trouble. Rockwool needs to be free to dry out evenly. Cutting off the oxygen by burying it under soil is not a good idea.
I would rather err on the side of caution when it comes to high quality genetics and Medical Marijuana growers who cannot afford to lose there seedlings. I stand by the tried and true method of never burying seedlings deeper than the soil level. after all; Thsi grower is talking about soil. 
I do it all the time in soil, although I do admit to usually using jiffy peat or coco coir plugs mostly, and if I do use rock wool it is started in a 1.5 inch plug similar in size to the the peat/coir plugs, and I suppose this could make a difference, true enough, it is probably better to be safe with larger rock wool cubes, especially if you have limited genetics.
It sounds like Rock Wool cubes are not a favorite. The place I bought them swears by them. So no I am going to plant my 3" sprouts in my 1" wool cubes into 4" pots with coco soil. I am then going to put those pots back under my dome with the florescent light that is approx. 2" from the plants. There is a tap root coming out of the bottom of the wool cube. I think in the future I will use peat pots or ??? .My starts are now 16 days old.
Any feedback appreciated…
Just not my favorite. They work very very well for certain types of grows, I’m not knocking them.
I am confused… so I plant this rock wool cube into the 4" pot with the coco soil. Then put it back under the florescent lights until a stronger root system is established…
Coco and soil mix? Or pure coco and it is a soiless mix? And yes you will need to return them to being under a light to continue to have them grow roots or grow anything otherwise. I wouldn’t think you need to put them under a humidity dome with true leaves and a larger growing medium that can hold more water longer.
I was sold Cocogro - Premium Organic Soil less grow media. Would you recommend mixing starter soil into this? My rock wool cubes are 1.5 ". Latewood talked about not planting the rock wool below the surface: (There is If you plant Rockwool cube below the surface you are risking too much dampness at the stem, and are asking for trouble. Rockwool needs to be free to dry out evenly. Cutting off the oxygen by burying it under soil is not a good idea.) Not sure what the heck he is talking about. I have some additional seeds to germinate and I will not be using the rock wool on these. Will try the peat plugs or just sprout and go into dirt… seems easiest.
What he says is true, if the rock wool cube holds too much water after being buried below soil or media you could kinda drown the roots. I think he may have thought you were using the really big 4 inch cubes or maybe not, either way what he says is good advice if you want to be really careful. The roots, believe it or not, love oxygen and the leaves love CO2, and there are other opposites between the roots and leaves as well, the leaves love light and the roots are photophobic(don’t like light). I really don’t think you’d have much of a problem if you want to lower the height of the seedling a little by adding some coco above the cube’s surface, but do not cover or get too close to the embryonic leaves(cotyledon). And be extra careful about over watering. What you germinate your seeds in has a lot to do with what you are eventually going to plant the plant in before you flower it. If you are going to grow the plant mostly in soil, what you say makes a lot of sense, if you are going to grow in large rock wool, rock wool cubes makes sense.
Do you think I should add some starter soil to the coco? So if I understand this correctly, the rock wool never disintegrates. So when there is a good root ball would I then take it out of the rock wool to plant in my 5 gal pot? Like I said, on my next go around I will not be using rock wool. Thanks heaps for all the help. Really appreciated.
No, there will be roots growing through the block, so leave it alone. You can, for certain, bury the block – at the very least – even with the surface of the coco or soil. The silicon and other mineral nutrients in the rock that the wool was made from will still be of benefit to the plant. I’m not sure about the starter soil but I also don’t think it would hurt. When this small container is almost rootbound or is rootbound, then transfer this new root ball, including the wool block obviously, into the 5 gallon pot. And actually you may want an intermediate size, or two, to help develop the root ball. I’m mostly a DWC guy, so I’ll let Latewood help you in more detail on that kinda stuff.
Thanks… I’m at least learning a lot from this. BTW, what kind of guy are you??? DWC?
Deep Water Culture hydroponics, lol. Sorry, see, like with Latewood’s oxygen comment, we sometimes forget not every body knows some of these things. I guess we can sound crazy sometimes.
Actually that is kinda a good segue and related. The reason you can drown your roots by over watering is the roots will use the oxygen in the soil quickly and if there is not enough aeration in the soil, the oxygen won’t be replaced very easily in water logged soil. This is also why in DWC you can grow roots right into the water itself, because you are aerating the water and keeping dissolved oxygen levels high.
top the stem and very top at a certain you will have short stubby buds