There are many ways of displaying large plants and trees.  You can make built-in beds, use purpose-built planter boxes, dig tree pits or buy ready-made tree containers.

Your choice may depend on the look you are trying to achieve, whether you are installing plants in a new building, whether you want to be able to move the plants in the future, cost and the timescale you are working to.

Tree pits

Tree pits are basically holes in the ground where you plant a tree.  They are usually (but not always) found on the ground floor of a building and they are used when you want your trees to be planted at ground level.

Tree pits are usually lined with a waterproof membrane and can be treated as a sealed plant container.  The top picture shows a tree pit that has a made-to-measure cover which can be covered in a decorative mulch, such as bark.

Covers like this, that are flush with the floor level, are useful for several reasons.  First, the soil level will be below floor level and may be uneven.  The covers will hide the soil surface and protect people from tripping or stumbling into the hole.

Secondly, the covers deter vandals from burying rubbish in the soil - a useful feature in places such as shopping centres and other public areas.

Built-in beds

These are planting beds built in to the fabric of the building.  Often, they are made from materials such as stone, concrete and brick, and they can be faced with materials used elsewhere in the building to match floors and walls.

As with tree pits, they need to be fully lined and made waterproof (unless the bed has drainage to a soakaway or to the waste water system).  Beds can be lined with rigid plastic liners or with flexible polythene or butyl materials similar to that used to line ponds.

It is common to have a layer of light expanded clay aggregate (LECA) at the bottom of the planting bed to allow excess water to drain from the soil.  This layer is separated from the soil by a sheet of semi-permeable fabric that will allow water to pass through it slowly into the LECA sump.

The LECA sump should be fitted with a tube to the soil surface.  This allows air to get to the roots.  It can also be used to pump out any excess water that builds up in the sump.

Made-to-measure planters

Planter boxes can be made for any building.  They can be fabricated out of metal, glass reinforced plastic (fibreglass) or wood and can be finished in any material to complement the finish of the building's interior.

The advantages of made-to-measure planters is that they can be moved (although they will be heavy) and they can be installed at a late stage in the building's construction.

Planter boxes can also be made away from the building and assembled on site just as they are needed, which may be ideal if the building schedule is tight.

Ready-made planters

It is possible to get very large ready-made plant containers suitable for all plants, including large trees.

They are often made of glass reinforced plastic (fibreglass) or metal, and are available in a variety of shapes, sizes and colours.

The planters on the right are made from metal and have been placed into a recess in the floor.

Below is a tree container made from glass reinforced plastic.  This example has a diameter of approximately 2 metres (6' 6") and would be suitable for trees up to 3 - 4 metres in height (10 - 13 ft).

Click here to find more information about plant and tree containers.