Designing With Plants On Podiums – Problems You Need To Consider

As a designer, I am working on more projects where the garden does not touch the earth. They are becoming part of multistorey buildings or on top of car parks. They are climbing up walls and screening areas we don’t want to see. Designers are trying to spread the “green” across the city. Designing with plants on podiums and buildings is one way to do this.

These types of gardens can be amazing. Yet, they are not without their challenges. A little thought at the beginning of a project can ensure a lot less pain later on when designing with plants on podiums. Missing some of these steps can have consequences for the longevity and health, of the plants. If they establish at all! To maximise the success of these novel (but fragile) green spaces, there are 5 key points you need to consider.

1) Plants need good soil to grow.

This might seem an obvious thing to state. However, many a drawing has crossed my desk that shows beautiful plants all over a building. Now when I ask where the planters are and how much soil volume I have to work with I get crickets….

There is a direct relationship between the volume of soil a plant has to grow in and how much shoot and leaf growth it will produce. simply put:

root volume = shoot volume

There are things you can do to help plants in smaller volumes of soil. But it’s not the same for every plant. Keeping this formula in your mind when designing is a great starting point.

2) How much of the building do the plants need to cover?

There is no climber that can climb 5 stories up a building. This just doesn’t happen. If you see 5 stories covered in vegetation it’s because, at some point, there is soil for more plants to grow. So, you need to think about how you are going to incorporate more soil into the structure.

Climbers covering the wall of a building
Photo by John Moeses Bauan on Unsplash

3) Soil is heavy

When filled with water and plants, soil can become very heavy. This has implications for the structure of the building. Think about the implications on your design. There are soils produced to be lightweight. Designed for plants out of the ground but they still add weight to your building.

4) Plants need light AND water

Plants do not grow in the dark, nor do they grow without water. It might seem like some plants can. These ones have adapted to a very specific natural environment (with light and water). Plants in pots or on a podium need access to water at times. The reverse of this is also true, plants need to have good drainage. They cannot sit in waterlogged soil.

Plants need light. While some plants can grow in very low light environments. these species will not give you the look you are after.

5) Plants need maintenance

One of the beautiful things about plants is that they are always growing and changing. As a result you cannot leave them to fend for themselves and expect them to always look amazing. If you want the climbers to cover the whole wall you need to train them to do this. If you want a perfect square hedge, it needs to be pruned. The design is going to required care and attention but how much will depend on what you are designing. The more stories involved, the more expensive it can get.

Green Wall on the side of a building
Photo by Paweł Czerwiński on Unsplash

In summary 5 key points to think about while designing

1) Plants need good soil

2) How much of the building do the plants need to cover?

3) Soil is heavy

4) Plants need light AND water

5) Plants need maintenance

Use this checklist every time you want to design with plants and think about what it means for your design. Get advice early on in the design process. It doesn’t cost anything to have a chat with someone about what your options are. This can save a lot of time and energy later on. Have fun with it. There are amazing examples out there of successful podiums, planters, and greenwalls.

If you want some help feel free to call us about your project we are happy to chat through ideas and options with you.