I don’t know if there is a collective noun for houseplants in general, but a group of orchids is a rarity, a group of cacti is a spike and a group of succulents is a reservoir.
There are advantages to grouping your houseplants:
- You can plant complimentary houseplants together in a single large pot so that they provide a more natural scene and all the plants can get watered, fertilised and cared for at the same time.
- Grouping individuals of the same species together can enhance the effect of the plants.
- You can group individually potted plants together, even if they have different requirements for watering, nutrients and potting mix. This will also give a more natural scene.
- Grouping houseplants increases the humidity around the plants helping prevent the leaf tip damage often caused by dry indoor conditions.
- Grouping individuals of different types together means they can be arranged so that shade-loving plants are provided shade by the light-loving plants.
- Grouping individuals of different types together give displays of mixed colours and textures.
There are advantages to individual houseplants:
- Specimen plants may be best shown off as single plants in a single pot so that their growth is not restricted.
- Single plants can give a dramatic architectural appearance in a home or office.
- Individual plants can more easily be given the care that the species needs.
- Smaller spaces may be more suitable for individual plants.