While it is generally more practical to plant holly shoots and cuttings rather than grow a holly plant from a berry, if you are set on raising your holly plant from absolute infancy, it can be done. However, you will need a lot of patience, and you should be aware that these plants often take years to develop their own berries. Some never do.
Plant your holly berry in the early spring. This will give it time to germinate and get started growing before it gets cold. However, it can take 16 months to three years for the four seeds in the berry to germinate, so you'll have to be patient.
Give your berry a good growing environment. It should be planted in full sun in loamy, slightly acidic soil. If your soil is neutral or basic, add some acidic plant food and fertilizer to the area to help your holly berry feel at home. The berry should be planted about a finger length into the ground. You will need to cover it or a bird is almost certain to eat it.
Make sure that your berry gets moderate water. Usually, this will be provided by rainfall. However, if the soil is completely dry, moisten it so that the berry does not become parched.
Mulch your plant once it sprouts. Young hollies are highly susceptible to freeze-thaw damage because their roots are so shallow. Surround your baby with a layer of mulch that extends as far as the farthest-reaching branches.
Continue to give your plant fertilizer every fall and spring. This will help the seedling grow and develop into a full-fledged, beautiful holly bush.