The Fine Art of Cloning

by pH

Go Back


The Question Was Asked:

> I have been having a very hard time cloning.  
> I have read many grower's guides, but their references to cloning all
> seem to be too vague, as if it was a simple thing to do... which it 
> probably is.

It is, once you've done it successfully :-)

> I am a soil grower and have no experience with hydro systems at all (I 
> know this is your specialty) and have been using vermiculite/perlite 
> combination in a styrafoam cup for rooting with no luck.  I use rootone to 
> stimulate growth, watering and misting daily. 
>
> Would it be easier to use a piece of rockwool and then transplant into 
> soil?

YES! Use rockwool cubes for cuttings. They're about 1.5 inches square, wrapped in plastic, and have a HOLE for the cutting. There are also cubes for germinating seeds but they are not wrapped, are smaller, and have a dimple instead of a hole. I usually poke a 1/8 inch diameter pointed stick in the hole to deepen it to a point 1/4 inch from the bottom of the cube (don't go through the cube). That allows for approximately 1 inch of stem to be in the cube. Treat the rockwool by soaking overnite in a 5.2 pH 1/2 strength nutrient solution (If you're using General Hydroponics nutrients, that would be 2.5ml of each component per gallon of water.) Then before using squeeze out excess solution, and rehydrate with a 6.5pH solution of the same strength. In other words mix a gallon of 6.5pH solution, then use some of it to adjust to 5.2pH for the soak. Use the remaining 6.5 pH solution until the clones root.
[NPK Note: Rather than the individually wrapped cubes, Grodan manufactures a sheet of 50 cubes which fit perfectly in a standard tray/propagation dome. ]

I use Hydrofarm liquid cutting concentrate, other similar products may be OK but I have been happy enough with the Hydrofarm stuff not to bother with anything else. Mix 1 part concetrate to 2 parts distilled water (I've seen labels printed wrong, so if you see the label reading mix at 1:20 ratio it is wrong and should be 1:2). I have used Rootone powder but found it not to be as good.

When taking a cutting always plan on having at least one node underground in the hole, and 4 to 6 nodes above. My cuttings are about 2.5 to 3.5 inches tall plus appx another 1 inch below the surface. The stem width of my cuttings (at the cut) average 3/32 to 1/8+ inch. Trim off the leaf/shoot that goes underground with a razor blade before taking the cutting, and make the diagonal cut on the stem about 1/4 inch below it, use a new razor blade with a small piece of wood behind the stem to serve as anvil for making a clean cut. Then IMMEDIATELY dip the bottom one inch of the cutting in the rooting liquid for about 15 to 30 seconds, tweaking it to dislodge any air bubbles that may be present. Then gently push it into the hole. I usually use large tweezers to poke into the rockwool about 1/2 inch from each side of the cutting then squeeze the rockwool to hug the stem.

The first night the cuttings will droop, the second day they will start to lift their heads.

> If I did, when the roots come out the bottom of the rockwool should I 
> remove the rockwool and put the roots into soil?

NO, when you use rockwool you'll know why you wont want to remove it from roots. I've taken clones rooted in rockwool and transplanted them directly into a pot with soil (to give to friends) with no problems at all. As long as roots can be seen coming from the rockwool cube it can be transplanted to soil as if it were a ball of soil. You can remove the plastic wrap. Thats the joy of rockwool, virtually no transplant shock from disturbed roots.

> Next question is the area of supplying nutrients to the rooting stem. 
> How do you recomend doing it?

cloning chamberNutrition is not as much of a concern as moisture is.

Leave the cube in a humidity tent at around 80 to 85 degrees F, with about 30 to 40 Watts/sq ft of fluorescent lighting on for 24 hours a day. The cube should NOT sit in water. As long as humidity is high you can spray with the 6.5 pH solution twice a day for the first 2 days, then once a day until it roots. But the humidity must be high, you should see condensation inside on the tent walls and maybe the leaves. I also spray the walls of the tent to keep it humid. Spray only the leaves not the cubes, and don't move the cuttings to check for roots until the eighth day. Keep in mind that the longer you have humid conditions the more likely it is to get mold or fungus. So rooting quickly is one way to avoid lengthy humid conditions.

When you first see the cutting is rooted through the cube bottom you can stop spraying and start watering the cube, let the solution drain from the cube. This is a critical time, when you see roots water the cube, and open the tent a little to allow humidity to escape AND CHECK EVERY 20 MINUTES for ANY SIGN of wilting. If after the 1st hour with no wilting open the tent a little more, and check every hour. After 4 to 6 hours with no wilting you're ready to rock n roll.

If any clones START to wilt replace the tent, spray leaves, and try again the next day. If you have some rooted some not, go for the humidity for a couple more days.

Here's what I've tried: Using pyraponics nutrients, in cups, with sphagnum and rootone I'd root in 21 to 30 days, but clones were sickly looking and most barely survived. Using Hydrofarm Bloom nutrients with rockwool, and HF cutting concentrate, I'd root in 11 to 21 days with healthier looking clones. Using General Hydro Flora nutrients and rockwool, and HF cutting concentrate, I root in 8 days with great looking clones.

So there IS a difference in nutrients, medium, and rooting compounds.

BTW use a fresh mix of nutrients, and keep the bottle sealed. pH can shift radically but usually wont do so for the first 10 days if the bottle's kept sealed, out of light, and at room temperature.

And don't forget HUMIDITY, HUMIDITY, HUMIDITY. But don't overdo it for too long or you risk mold and damping off.

> Also, is the air pump helpful in rooting with rockwool? It probably 
> serves no purpose in rooting in a cup with verm/perlite.

NO, not at all useful for me.


More On Cloning

Once they have rooted and are growing you won't need to mist them, watering the cube should suffice. I ususally put the newly rooted cube in a very shallow container (cut off about 1/16" from the bottom of a plastic drinking cup), this holds some solution and keeps the roots from air pruning. The clones will use the solution fairly quickly so there's no danger of drowning, just make sure the container is "very shallow". It also serves to contain the roots, and they will grow in a circular direction inside the container. When time comes to transplant you'll have nice long roots with no air pruning having taken place.

HTML'd by NPKaye
http://npkaye.home.ml.org