Taking Clones

A clone is a cutting taken off a living plant that grows roots and becomes its own plant. It is genetically identical to the one it came from, which means the plant you liked is repeatable instead of a one-time accident.

That is the real reason to learn this. Seeds vary, even within a pack. When one plant out of four turns out noticeably better than the others, a clone is the only way to have it again.

The timing nobody mentions#

You have to take clones before you flip to flower, or in the first week or two after.

Once a plant is well into flowering it stops being a usable donor. Cuttings from a flowering plant will root eventually, but they take much longer and have to revert to vegetative growth first, which takes weeks and produces strange, twisted growth on the way.

So the window is while the plant is still in veg, or right at the flip. By the time you can tell which plant is best, usually well into flower, the window has closed.

The workaround is to take cuttings from every plant at the flip, label them, and throw away the ones whose mothers turn out unremarkable. A rooted clone costs almost nothing to keep for a few weeks.

What to cut#

Pick a shoot from the lower or middle of the plant. Lower growth roots more readily than the tops, which are hormonally oriented toward vertical growth rather than root production.

You want a cutting four to six inches long with at least two or three sets of leaves and a node or two that will end up below the medium. Pencil thickness or a little thinner. Avoid anything woody.

Take more than you need. A reasonable expectation for a first attempt is that somewhere between half and three quarters will root, so cut six if you want three.

The actual process#

Have everything ready before you cut anything, because a cutting drying out is the main thing that kills it.

1. Fill a cup with water. Cuttings go straight in. The enemy here is an air bubble entering the stem, which blocks water uptake.
2. Soak your medium. Rockwool cubes, peat plugs or a light airy soil mix. Rockwool wants a soak in pH 5.5 water first. Plugs want to be damp, not dripping.
3. Sterilize a blade. A razor or scalpel, wiped with alcohol. Scissors crush the stem.
4. Cut at a 45 degree angle just below a node, and put it in the water immediately.
5. Trim the cutting. Remove the lower leaves so the bottom two inches are bare stem. Cut the remaining large fan leaves in half across the tips. This sounds brutal and it matters: a cutting has no roots, so every square inch of leaf is losing water it cannot replace.
6. Dip in rooting hormone. Gel or powder, both fine. Pour a little into a separate container rather than dipping into the bottle, which contaminates it.
7. Insert into the medium without wiping the hormone off. Make a hole first with a pencil rather than pushing the stem in.
8. Into a humidity dome, under weak light.

The two weeks that follow#

This is where people go wrong, and the errors are all variations on doing too much.

Light should be weak. A clone has no roots and cannot support strong growth. Low intensity, 18 hours on. A T5 or a dimmed LED well back. Strong light forces transpiration the cutting cannot sustain.

Humidity high, then declining. Start near saturation with the dome closed. After about four days start cracking the vents, and over the following week open them progressively. A clone kept at 100 percent humidity until the end has no reason to grow roots and will sit there indefinitely.

Do not overwater. The medium should stay damp, not wet. A waterlogged plug has no oxygen, and rot in a cutting is quick and final.

Do not feed. There are no roots to take up nutrients. Plain pH adjusted water, nothing else, until roots appear.

Do not keep checking. Pulling a cutting out to look at the stem breaks the root initials forming on it. Wait for roots to appear at the bottom of the plug.

Expect seven to fourteen days. Some strains go faster, some take three weeks. A cutting that is still green and firm at day fourteen is still in the game.

After it roots#

Once white roots are visibly out of the plug, pot it up into something small, maybe a one quart container, and treat it like a seedling that skipped the fragile first week. It will grow faster than a seedling of the same age because it is already mature tissue.

Bring light up gradually over several days. A freshly potted clone under full strength light will bleach.

Keeping a mother#

If you want a strain indefinitely, keep one plant permanently in vegetative growth under 18 hours of light and take cuttings off it as needed. That is a mother plant.

It costs you space and electricity year round, which is the real consideration in a small tent. The alternative most home growers use is a rolling chain: take clones from this run's best plant, flower those, take clones from the best of those. No permanent mother, no dedicated space, and the genetics carry forward anyway.

One warning either way. Clones carry pests, and a cutting from somebody else's plant is the most common way mites arrive in a clean tent. Quarantine anything from outside your own room for two weeks before it goes near the rest.