Taking cuttings of houseplants is simple enough – in most cases, you just stick the cutting upright in moist potting mix and you’re off to the races! – but you’ll have more success by covering the still-fragile future plant with a mini-greenhouse of some sort. After all, cuttings don’t yet have roots and can dry out very quickly when exposed to the air, losing water to evapotranspiration. This is doubly true for cuttings with thin leaves. If you cover them with a mini-greenhouse, though, the air inside will be saturated with moisture, and therefore the cutting will no longer lose its precious water to transpiration, giving it a better chance of recovery.
You can use just about any transparent container as a mini-greenhouse: a transparent plastic bag (prop it up with coffee sticks so the bag doesn’t collapse on the plant), a wide-mouth bottle turned upside down, a clear plastic container for vegetables, fruits or pastries that you recycled, or even the bottom of a soft-drink bottle you’ve cut specially for this purpose.
Remove the greenhouse when new leaves start to appear, indicating that rooting has begun, which may take a few weeks. Your cutting is now an officially rooted plant, ready to grow on its own and greenhouse care is no longer needed.
Some Cuttings Like It Dry
If the vast majority of cuttings benefit from high atmospheric humidity while they are rooting and should therefore be placed in moist soil and covered with a mini-greenhouse, there are some cuttings that root best under drier conditions. And this is especially the case with succulents, a group that includes desert cacti, crassulas, sedums, aeoniums, and many others.
For these plants, cut off the top of the stem, but don’t plant it right away. Let it dry for a while, until the wound callouses over, before potting it up. You can simply lay the cuttings on their side on a plate or a shelf while you’re waiting. It takes 2 to 3 days for most succulents to form a callus, but a month or more for those with very thick stems (large cactus and euphorbias, especially).
Stick the cutting upright in a pot of dry soil (not moist as you would for other plants) and don’t water right away. Wait until you see signs of growth, which can sometimes take a month. Yes, as odd as it may seem, these plants will more easily produce roots in dry soil! And of course, don’t cover them with a mini greenhouse, as this could lead to rot!
Once new growth appears, start a normal watering program and your “succulent cutting” will soon be a thriving plant!