A $6 jar of rooting compound pays for itself in plants.

Rooting compound is probably been the single best gardening investment we've made.

Rooting compound is a plant hormone that stimulates root production. It's used to propagate plants from cuttings, and gardeners are often willing to give away cuttings for free.

Pictured is a propagated rosemary with the root side up, just before planting. It started out as a twig from a neighbor's rosemary bush a couple of months ago. (That's kale and onion in the background).

Apartment gardeners can use rooting compound to grow herbs and flowers. Tomato vines can be rooted from suckers. Homeowners can use rooting compound more extensively.

We've used rooting compound to propagate ornamental hedges from a single plant, and we've used it with some of the plants in our flower garden such as rock purslane. Right now we have roses and geraniums growing roots and getting ready for planting.

Depending on the climate and the plant species, cuttings can be rooted either in a jar of water (with rooting compound and maybe a pinch of fertilizer), or else given a light coating of rooting compound and planted directly in the soil. When propagating flowering plants it's best to pinch off the flowers when preparing a cutting, and to remove all or most of the leaves. This rosemary was propagated in water.

To estimate the savings, first find out whether a species propagates from cuttings and and whether a gardener you know will gift cuttings. Then look up the price of nursery starts. For instance, pink dragonfruit cactus sells for $30 per plant locally: we've saved $150 by propagating our five plants instead of buying them.

We bought a small jar of rooting compound ten years ago and it's still half full. Although there have been viral videos about propagating roses using a potato, IMO rooting compound is the better deal.