Plant Selection: Interior and exterior landscapes use plants from different parts of the world due to their behaviours and tolerances.
Substrate: the substrate used when planting indoor and outdoor plants is very different due to the landscape, irrigation, and plant needs.
Lighting for indoor plants needs really careful consideration and sometimes requires auxiliary lighting to achieve the right levels.
When we're first getting involved on a project there's sometimes confusion in the contractor's mind as to why we're needed when they already have a landscape architect.
Sam and I sat down and brained out what it is that makes such a fundamental difference in our disciplines, despite both dealing with plants in the built environment.
It's worth mentioning that Sam started out life as a landscape gardener before moving over to interior landscaping, so he's speaking from a place of experience!
We also recorded a podcast on this topic; if you'd rather listen, you can find that here:
To understand the distinction let's begin with plant behaviour. Outdoor plants, which landscape architects typically manage, are subject to natural seasonal cycles. They bloom in the spring, may enter dormancy in the winter, and are constantly influenced by environmental factors such as rain, wind, and varying soil conditions.
In contrast, indoor plants are cultivated in a controlled environment. They are shielded from harsh winters and strong winds, thriving in stable, consistent conditions designed specifically for their needs. While a landscape architect may excel at designing outdoor spaces with these natural cycles in mind, the indoor environment demands a specialist who understands how plants will behave indoors.
Seasonality is another crucial aspect of the two disciplines. Outdoor landscapes are inherently designed with changing seasons in mind. Designers consider how a space will appear in the spring, with blooming flowers and perennials, in autumn with colourful leaves, or even in the bare beauty of winter.
Indoors, however, plants exist in a continuous state. There is no autumn or winter to contend with, meaning the design and care for these plants must reflect that consistency, maintaining a balance throughout the year.
The underlying elements of interior landscaping also differ significantly from elements of outdoor landscaping. The substrates and build-ups used indoors are generally simpler compared to the complex soil preparations required outdoors. Outdoor landscapes demand intricate drainage systems to cope with the varying weather conditions, while indoor plants rely on substrates designed to retain moisture and provide stability. The focus shifts from managing external environmental factors to creating the ideal internal conditions.
It's also important to consider the impact of build-ups and substrates on factors such as loading. For example, a recent scheme we reviewed included large boulders, large statement trees, and large volumes of soil. When these elements are designed above the ground floor, there is a high chance of exceeding the floorplate loading.
Watering is another area where the two disciplines diverge. Outdoor irrigation systems must account for evaporation, rainfall, and large-scale watering needs. Indoors, however, is where you’ll find that precision is key. Indoor plants require exact amounts of water, with skilled horticulturalists who know exactly how much each species needs. This is where capillary action plays a significant role, allowing plants to absorb moisture from the substrate as needed.
Outdoor plants receive their light from the sun, leaving little room to alter light quality. Landscape architects often measure lux to ensure that the environment is not too shady for certain specimens. Indoors, however, is entirely different. Interior landscapers collaborate with horticultural lighting engineers to perfect the lighting conditions, often measuring it in micromoles rather than lux. It’s a science that requires precision to ensure plants get the specific spectrum of light they need to thrive indoors.