You have too much light on them my friend. And get rid of that heating pad. Here's my method, I'm near 100% survival rate. Out of the last 200 clones I took only 1 didn't make it.
Take rockwool cubes. Mix half strength sensi bloom A&B or another A&B bloom formula, half strength. I use 4ml of A and 4ml of B. Add 3ml per gallon of thrive alive or another b-1 supplement. Add rhizotonic at half strength. It usually comes out to about 550ppm's. Mix solution and pH the solution to 4.8pH and presoak the cubes for a few hours. I like to soak for 24 hours. 4.8pH may seem low but most people don't know that rockwool is high in alkaline. After your soak you will notice that your solution will have risen to about 5.5.
Next take your cuttings. Cut 1/4 inch below node (at least 3 nodes down from top). Cut at 45 degree angle with cut part of stem on opposite side of node. Starting at node, scrape the stem so the outer skin comes off about half way around the stem. Don't go too deep to the point where you are seeing the inner white part of the stem. The scraped away skin is where the roots will grow from. Remove leaves that are close to bottom of cutting. I like to leave two node sets of leaves on my clones. Cutting the tips isn't necessary and doesn't help the plants no matter what people say. The only reason for it is if you have a crowded tray and need light to penetrate to lower clones. Personally I only like to do 25 clones per tray so they all get enough light. Once you remove the leaves dip your cutting into Clonex and swirl it around for a couple seconds so you have a nice coating of blue goo on the end of your stem. I have used rootech, olivia's and clonex and clonex has given me the best results so far.
Next insert your cutting into the rockwool cube. *** Don't use the premade hole in the cube! *** this is important. You want the clone cutting to be in there snug. The holes often leave gaps between the stem and the rockwool. This is bad for rooting and also invites mold and disease. If the cutting isn't strong enough to penetrate the rockwool it isn't a cutting worth taking.
Once all your clones are taken and in the tray foliar feed them with 15ml per gallon of rhizotonic. Be sure to spray the tops and bottoms of the leaves. Spray the inside of your humidity dome and cover the tray.
Place the tray under a single t5 or t8. The lights with multiple t5 bulbs (4-8 bulbs) are too strong for what the plants need at this stage. ***DO NOT use heating pads for cuttings in rockwool*** You don't need a heating pad. Keep the temp inside the dome between 65-75. Try not to have too much fluctuation. I keep mine right at 70 degrees. Don't open vents or lift humidity dome for at least 7 days. I usually go 10 days and check for roots. Keep the humidity dome on until you have roots or your cuttings will wilt and die. Once you see root growth you can move cutting under stronger t5's until transplant. Until roots form though they only need a little light.
BE PATIENT AND BE STERILE. I have had strains that take 7-10 days to root and I've had others take up to 21 days. You just have to be patient and wait. Use a brand new razor or scalpel. I like to light mine with a flame, wipe off, and let cool before taking cuttings just to be safe. Also make sure your humidity dome and tray have been cleaned to avoid molds. Use bleach or alcohol and make sure you rinse all off before putting your cuttings inside.
People will say use only water, lift the hood and give them fresh air everyday, mist them once a day, cut all big leaves in half, flush your mother the week before harvest, and the list goes on. That is all false if you want the best results. I stand by this system tried and true. As long as you have healthy, disease and pest free, mothers to start with you can't go wrong with this system.
