Rose (Rosa spp.) propagation in potatoes is a folk-gardening trick that seems to work well because the potato keeps the tip of the cutting at the perfect moisture level to develop young roots. Roses are often propagated from young, softwood cuttings, which take root and grow into new plants. With the potato propagation method, the potato is left in the soil to rot naturally as the roots grow. Successful propagation depends on sterile equipment because roses are highly susceptible to disease.
Disinfect a pair of bypass pruners and a screwdriver or punch tool in a 10-percent solution of bleach diluted at a rate of 1 part bleach to 9 parts water. It helps to mix this solution in a spray bottle and keep it in your garden shed for easy access when you need to disinfect tools.
Cut a section about 6 to 8 inches long from a healthy, green tip of a rose plant with the bypass pruners. Make the cut at about a 45-degree angle to increase the surface area that can suck up water. Place the cut end in fresh water immediately after cutting before the wound callouses; otherwise, you must make a fresh cut immediately before inserting it in the potato.
Puncture the side of a whole potato with the screwdriver or punch tool to make a hole at least 2 inches deep and slightly wider than the rose cutting's diameter. Choose potatoes with high moisture content such as white potatoes, red potatoes or Yukon Gold potatoes.
Dip the cut end of the rose cutting in rooting hormone powder and shake off the excess powder. This step is optional, but rooting hormone encourages rapid root growth.
Push the cut tip of the rose cutting into the hole in the potato. Make the hole slightly wider, if needed, to avoid damaging the stem.
Bury the cutting in the ground just deep enough to cover the top of the potato, but leaving the cutting exposed. You can plant directly in the ground in spring while the weather is still cool, but if you take the cutting in fall, it should be started in a pot and grown over winter. Fill the pot with sterile potting soil, using a bagged mix or your own blend, such as equal parts sphagnum peat moss, finished compost and perlite.
Insert a stake in the ground beside the rose cutting and tie the cutting loosely to the stake to hold it straight. A thin stick such as a chopstick works well as a stake. The stake can be pushed into the potato without problem.
Water the soil around the cutting just enough to make the soil moist and slightly crumbly without making the soil wet. Water the cutting as needed to maintain this level of moisture. The potato and cutting will quickly rot if the soil is kept too wet.
Pull gently on the tip of the rose cutting after a couple of weeks to check for resistance that indicates strong roots have developed to anchor the cutting in the soil. If the cutting pulls up, push it back into the soil and potato and wait another week or so before checking it again. Remove the stake when roots develop. If desired, you can feed the rose cutting with a light application of a general-purpose fertilizer after roots develop.