Taking cuttings from the top, middle and bottom of the plant will cause different rooting times. The top cuttings have more Auxin's in them so root faster but grow slower. The middle and down root slower but grow faster. Auxin's are organic hormones that are natural in the plant and when you cut the plant the Auxin's move to the cut to start root development. As you are having issues this is what I would do.
pH your medium, rockwool, peat pots what ever, do not add any food and if you have city tap water let it sit our for a few hours so it gets to room temp. Adding food will slow rooting, tap water has enough stuff in it to grow roots. Well water that is higher than 400ppm is not so good, if you have RO add 1/2 regular water to 1/2 RO.
Cut the clones all from the same area and put a little rooting gel/powder on it. DO NOT CUT AT AN ANGLE CUT THEM STRAIGHT ACROSS. Cutting at an angle will only take more time to root. The only exception to this is if you are using an aero type cloner, the angle cut will provide water to the leaves of the clones in the cloner. When using a tray the dome provides 100% humidity to the leaves of the clones so don't angle cut.
Using globs of rooting gel/powder is not better and in fact will slow down rooting, you just need a very small amount. If you go to one of the big box stores buy the rooting powder they have and buy the #1, #2 and #3, try the different # on a few clones to see which they like best. The different # have different amounts of IBA rooting hormones in them. Some plants like stronger and some like weaker IBA you need to see what your clones like. This is important because if you have to weak of a IBA they will take a long time to root, but if you have to strong the same will happen, you need just the right amount that's why they have different strength rooting gel/powder. The IBA (
Indole-3-butyric acid ) () causes the cut to callus over and than the roots grow, if you have to little it takes a long time to callus over and if you use too much it will just keep callusing over and over again and again. Have you ever seen a clone with a swollen stem where it goes into the medium? that's what happens when you use to much IBA.
Now that you have the clones cut and in the medium put a humidity dome on them and put them in the dark for a couple days, on day 3 put them under the light but put the light far away for the next day and than start to move it closer every day. The lack of light helps them start rooting as there is no light to keep the leaves growing, you want roots not leaf. Keeping the bottom warm will help but as it's still warm out you don't need to do that.
So I hope this has helped you understand how it all works and gives you some ideas to work with. The information is back by research and practical experiences.
I know people have been slash
cutting clones forever and they have good results, after all that's how I did it for years, but when you make a number of small changes they can make a difference in yield and after all that's what is all about.
Here are a couple shots of my ladies at 6 weeks there are 9 plants under 4 x 1000w, they are 4 1/2 feet high. Great clones make great plants.
