Gonna get on the soapbox: ditch the heat mats guys,
aquarium heater is the way... easier to get stable temps with warmed water.
Basically, you set your clone tray inside a hole cut through a tote lid, fill the tote with water and submerge an aquarium heater inside. Be sure the water touches the bottom of the nursery tray for best results (too much and it floats, not a bad thing tho). Place the temperature probe inside the clone tray, set thermostat at 80, fill with clones...mist the dome and clones only if humidity doesn't form on dome after 10 minutes on. Minimizing your misting is important... second behind stabilizing your temperature. Stable temp = stable humidity.
I've always cloned in rockwool, rinsed at ph 5.5 (tap+ph down only) and soaked in a light mix of plain water and 2ml/g GH rapid start at ph 5.8...be suer to shake the blocks lightly (no squeezing) so they're damp not wet. I prefer to use olivias or rootech, but have 90%+ success with most any gel. Brand new nursery flat and dome every time ensures things are clean. Highly recommend the
grodan 1.5" cubes, and the reddish plastic rack/tray designed to lift and separate the clones from the bottom of the nursery tray. Keep a bit of plain fresh water below the clones and change it daily (1/2" or so, just to bump up rh, NOT in contact with rw cubes).
It is important to remove the dome daily for incrementally longer periods of time, ie: day one is three sessions of 5 minutes dome off, day two is 3x 10 minutes, day three 4x 20 minutes, etc, and by day five I can leave the dome off for an hour or more at a time. The dome off periods really shock the plants, so be sure to set a timer and be diligent. By day 7 the dome is off all day (18hrs), only goes on for dark 6 hours.... dome off permanently around day 9-10, and roots start showing every day thereafter.
The rockwool begins to dry out after 7 days or so (waiting for this is KEY)... by minimizing misting the cubes will dry out naturally. This process of slow drying at the root zone along with the regimen of dome on and off really sends your new clones the message to root... the only thing left is being
very light on the first feeding of the new roots.
Over feed or feed too soon and your roots will stall. This is critical.
The color and weight of the rockwool cubes becomes your barometer for when to feed, so pay close attention or shoot some photos for reference on what wet and dry look and feel like. If 50% of the cubes are nearly dry (light in color and weight from drying), then its time to feed.
My mix is 20% strength canna substra flores bloom base with 2ml/gal rapid start at ph 5.8...mix up a few gallons so you have plenty of fresh solution for change outs between rinsing... After mixing up the nutes, I fill a new nursery tray tray 3/4 full (filled 2" deep or so) with nutrient solution and place the
grodan tray into the solution The important part is making sure the top of the water is 1/2" up the cubes on the
grodan rack thingy. After a minute of soaking I pick up the tray and tilt it back and forth to swish the solution around the cubes like a gold miner with a pan. Do this soak and swish/rinse process twice for best results. While you're swishing, try to keep the solution from splashing onto the tops of the cubes. Optimally the cubes will be dry at the top 1/2" and moist at the bottom 1" when you are done. Once you're done swishing, remove the tray from the solution and place it back into the hot water tote with 1/2" fresh plain water... a few days later and roots galore.
I've shared this method with a few new growers struggling with the clone hurdle and they all continue to follow the process like religion... which gives them the same 90%+ success rate. It is by no means perfect, but the method is reliable and a good place to start with minimal investment. I hope it helps.
Whatever you do, be sure to start with healthy cuts from healthy moms, follow a solid regimen that emphasizes the transition from moist nursed fresh clones to hardened new plants, and you will eventually get new copies of your mothers. Just stick with it and keep notes. You will succeed.
**As I wrote that, my state just defined any clone without flowers and less than 12" tall and around is a 'seedling' and therefore does not count as a plant. Nice. :)
Happy holidays, ftw