Take the Cuttings Before the Frost Does

The coleus on the step is the best it has looked all year, a yard across and every leaf a different red, and it has about six weeks to live. It is a tropical. The first real frost will turn it to black rags overnight, and no amount of cover will change that for long. But a four-inch piece of it, cut tonight and stood in a jar of water on the kitchen sill, will be a rooted plant by October and the same plant next June. The same is true of the impatiens, the begonia, the sweet potato vine and, with one change of method, the geranium. This is the cheapest thing you will do in the garden all year.

Why now and not in October

A cutting roots on the energy the parent plant has stored in it, and it roots fastest when the parent is still growing hard. Every cool night from here on slows that down, weeks before it does any visible damage. A cutting taken in the second week of September from a plant in full growth roots in days. One taken from a plant that has already sat through a couple of nights in the forties roots slowly if it roots at all. So the rule is to cut while the plant looks too good to cut.

In the South and on the coast, where frost is still two months away, nothing here is urgent. The same cutting works any week between now and November. But nothing is lost by doing it early either, and a plant that came from a September cutting is big enough by spring to give cuttings of its own.

How to take the cutting

Choose a soft green tip that has not flowered, or pinch the flower off if it has. Cut about four inches down, and make the cut just below a leaf joint, the node where the leaves meet the stem. That matters more than anything else on this page. The roots grow from the node, not from the cut stem between nodes, and a cutting with no node under the water or the soil is a stick that will slowly rot.

Strip the leaves from the bottom half of the cutting so that nothing sits under the water line, and pinch out any flower or bud. A flower on a cutting spends what the roots need. Two or three pairs of leaves at the top are plenty. If a leaf is very large, as on a big coleus, cut it in half across to reduce the water it loses.

Which plants root in water

Coleus is the easiest plant in the garden to root in water. Stand the cutting in a jar on a bright windowsill out of direct afternoon sun, change the water once a week, and white roots appear in a week to two weeks. Impatiens and sweet potato vine behave the same way. Begonias, the wax and the cane types, root in water reliably but more slowly, three to four weeks, and rot if the water is not changed.

Geraniums, meaning the bedding pelargoniums, are the exception. They can root in water and sometimes do, in four to six weeks, but they rot in a jar more often than they root. Give a geranium cutting a small pot of damp potting mix instead, lower leaves off, the cut end pushed in to the first node, and leave it alone in bright light for a month. Do not cover it and do not keep it wet. A geranium cutting wants to be slightly dry.

Light matters more than warmth for all of them. A cutting on a north sill in a warm kitchen sits and does nothing; the same cutting on an east or west sill roots. Direct afternoon sun through glass is the one thing to avoid, because it cooks the water and wilts a cutting that has no roots to drink with. Bright, and not hot, is the whole recipe.

Water to soil, and what to do when the jar goes cloudy

Roots grown in water are not quite the same as roots grown in soil, and a cutting moved from the jar to a pot sulks for a week while it grows the second kind. Move it when the roots are an inch or two long, not longer. Long water roots break and rot. Pot it in ordinary potting mix, water it in well, and keep it out of hot sun for a few days.

A cloudy jar means the water needs changing and the stem needs a look. Rinse the cutting, cut off any brown mush at the base back to clean green tissue, and start again with fresh water. If the whole stem has gone soft, that cutting is finished, and the cause was almost always leaves left under the water line or a cutting taken from a stem that was already woody.

Getting them through the winter

A rooted cutting in a small pot on a bright windowsill will grow slowly all winter, and slowly is what you want. Water only when the top of the mix is dry. Do not feed until March. Pinch the growing tip once or twice so the plant branches instead of stretching toward the window. By the time the nights are back above fifty in May the small plant is ready for the step, and it will be twice the size of anything you can buy in a six-pack.

The plant on the step will not see November. The jars on the sill are next summer, and they cost the price of the water.