Commonly called cinquefoil, the genus Potentilla includes approximately 500 species of flowering plants, including some commonly cultivated for their ornamental flowers and attractive palmate foliage. Most species of potentilla occur naturally in cool, alpine environments so they are an appropriate choice for woodland or rock gardens in U.S. Department of Agriculture plant hardiness zones 2 through 6. Propagating potentilla from seed is a reliable means of growing new plants; however, the new plants may not express identical characteristics to their parent plant because potentilla easily hybridises.
Harvest seed from a mature, healthy potentilla plant in late summer or early autumn. Pick through the seeds and remove any chaff or debris, as well as any seeds with damage or defects.
Combine equal parts compost, potting soil and horticultural sand. Mix the components until fully incorporated.
Fill several 8-inch, plastic nursery pots with the compost, soil and sand mixture. Apply 4 inches of water and allow it to drain.
Sow two potentilla seeds in each pot. Press each seed 1/8 to 1/4 inch deep, depending on the species of potentilla and the size of the seeds. As a rule of thumb, sow seeds to a depth corresponding to three-times the length of the seed. Sprinkle a layer of the compost, soil and sand mixture over the top of the seeds and lightly firm them in place.
Place the pots in a cold frame for the winter. Water the seeds to a 4-inch depth every ten days for the first month, then decrease watering to 2 inches every ten days for the rest of the winter.
Open the cold frame for several hours every day following the last frost in spring to allow the seedlings to harden off. Move the pots to a protected spot with filtered or dappled sunlight when outdoor air temperatures reach 18.3 degrees Celsius during the day and no colder than 4.44 degrees Celsius at night. Water the seedlings to a 6-inch depth every 10 days.
Keep the potentilla seedlings away from strong, direct sunlight during the summer and continue to water them regularly. Replace one monthly watering with a mix of 4 tbsp fish emulsion diluted in 1 gallon of water, to provide additional nutrients.
Plant the potentilla plants outdoors in mid-autumn. Choose a permanent bed with partial sun and average, well-draining soil.