This is not a list of plants that you regret buying and so never repeat your mistake, but rather buying a desirable plant and using it to increase your stock by propagation. In this way all the extra plants are free apart from the small amount of work involved. Of course not all plants are so obliging, but the ten on this list are easy to increase by this method. This information comes from an article by Marianne Lipanovich which I found on the Houzz website.

?New plants from old? might be one of the rallying cries of gardeners everywhere. These 10 plants are all fairly easy to propagate, giving you the chance to fill your garden or home with more of your favorites, or provide plants as gifts to friends and neighbors. There are numerous ways to propagate plants, such as collecting seeds and taking cuttings. If you?re new to this, start with these easy-to-replicate plants and go from there.

1. Hens-and-Chicks
(Sempervivum spp.)

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This succulent?s common name is a tribute to just how easily this short-lived plant produces its offspring. New rosettes form on the outer edges of the mother plant, which dies off in a few years, often after producing iridescent blooms.You can let the new rosettes of hens-and-chicks, aka houseleeks, spread naturally. If you want to plant them somewhere else, wait until the runner that connects them to the mother plant starts to wilt, then cut that and uproot the entire rosette.
Where it will grow: Hardy to minus 25 degrees Fahrenheit, or minus 31.7 degrees Celsius (USDA zones 4 to 11; find your zone), depending on species
Light requirement: Full sun to partial shade in hot desert regions
Water requirement: Low
Mature size: Varies from quarter-inch-diameter balls to 2 inches tall and 4 inches wide

2. Spider plant
(Chlorophytum comosum)

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Spider plant with dangling plantlets in an Australian vertical garden
The ultimate hanging container plant, spider plant is known for its plantlets, miniature versions of the parent plant that hang down from the ends of the leaves. You can leave them in place to enjoy, or cut them away from the plant to grow your collection.
You can also get the babies started in a new pot next to the mother plant, even while they are connected to the mother and you are waiting for them to form roots. Keep the soil moist during this stage and remove the connecting stem when the roots have formed.
Where it will grow: Generally grown as houseplants but hardy to 20 degrees Fahrenheit, or minus 6.7 degrees Celsius (zones 9 to 12)
Light requirement: Prefers bright, indirect light but can take partial shade to partial direct morning sunlight
Water requirement: Regular; keep soil moist but not soggy
Mature size: 6 to 12 inches tall and 6 to 24 inches wide