Berries from holly shrubs, known botanically as the Ilex species, can easily be planted to propagate new plants, although you will need to be patient. Hollies are more commonly propagated by cuttings, as the seeds will take anywhere form 8 months to 3 years to germinate and begin growing as new plants. This long germination interval is due in part to underdeveloped seed embryos and a hard seed coat, according to North Carolina State University. Fresh seeds should be collected and planted immediately in the fall to have benefit of the winter chill to stratify the seeds and advance germination.
Collect mature, ripe red holly berries in the fall. Break the red flesh apart from the seeds over a fine mesh strainer and rinse the seeds with water.
Sow the seeds roughly 1-inch deep in tilled up garden soil or in pots filled with moist, sterile potting mix. Plant many more seeds than you want eventual plants, as the germination failure rate can be as high as 50 percent. Young excess seedlings can always be thinned or transplanted at a later date.
Water the seeds and surrounding soil to drench them until water flows out the drainage holes. Keep the soil around the seeds evenly moist, but not soaking wet, all times until germination occurs and small green plants established.
Ensure that the seeds are held at a temperature below 40 degrees F during the winter. In climates where winter temperatures do not reach this low, cover the seed-filled pots with a layer of plastic film and store in the refrigerator for at least 2 months to cold stratify the seeds before planting the pots back outdoors. Ensure that the soil remains consistently moist but not wet the entire time.
Transplant the seedling plants into their permanent growing location when there are at least two leaf groups on the young plant. Transplant in spring after the last frost, in the summer or in fall before the first hard frost.