Broadleaf evergreens are best planted in early fall versus late fall, because their wide leaves are more prone to losing moisture over the winter (if the surface soil is too frozen for roots to replenish lost water), and the roots need time to establish in autumn prior to the soil freezing. As such, evergreens used as display plants indoors for the holidays and planted afterwards are typically conifers (needled evergreens), which are less prone to this issue because their foliage doesn't loose moisture as quickly. All evergreens can also be planted in the spring with no issues.

None of the winter-hardy plants used indoors for decorating should spend more than a week or two inside; they should not spend the entire winter indoors because they need a winter dormancy period to maintain a healthy growth cycle. Indoor air is too warm, not humid enough, and the light too dim (even with supplemental lighting) to support growth and photosynthesis; they likely won't stay dormant because they won't be getting the right environmental signals. Ideally, when live evergreens are used for holiday décor, they are kept outside until the last minute, brought in and enjoyed for a week or so, and then planted outside. Check them for water every couple of days while inside, as the dry and warmer air can desiccate the soil faster than it would dry while outside. If you do not yet have a location for it to be planted outside, put the pot outdoors in a sheltered location where it can stay cool/cold but above freezing and is able to be periodically checked for watering needs. You can also opt to plant it with the pot in a temporary location so you can easily pull it up for planting elsewhere in spring; in this way, the roots will have much better insulation than being above-ground all winter.

The holly variety 'Red Beauty' can be expected to mature around 7 to 10 feet tall and about 4 to 5 feet wide. Variety 'Blue Princess' matures about 10 feet or more tall and wide. Both can be trimmed to stay smaller, though this should be done in moderation, so it's best to find a location where each can reach as close to its mature size as possible. 'Blue Princess' will eventually need a male holly in the "blue holly" group to pollinate it for berries in future years; options include 'Blue Prince', 'Blue Baron', 'Blue Boy', and 'Blue Stallion'. The 'Red Beauty' should produce berries on its own (it won't pollinate the 'Blue Princess' though), but it too would benefit from the pollen of one of the aforementioned males. Only one male plant is needed to pollinate both of your hollies, though it doesn't have to be immediately next to either. If berries are not an important feature for the long term, then you don't need to worry about including a male in garden. A suitable location can be either full sun or mostly shade (or anything in between), though the foliage will be densest (and berry-set heaviest) in full sun. Soil should be well-drained, but they are otherwise not too fussy.

Miri

As usual, a wealth of information. I had my plans for the plants all wrong! Thanks for straightening me out, Miri.

You're welcome. Marketing can sometimes be a bit overly-optimistic with regards to plant care, though garden centers / nurseries are usually a bit more thorough in giving advice than plant departments in home improvement stores.

Miri