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Plants for the roof terrace and how to care for them

For you, your roof terrace is a green oasis in the sky. For your plants, however, this location can be a challenge. Not all plants are able to survive there.

While you relax on your roof terrace, the plants have a few things they have to endure: They are exposed to the elements, which they have to cope with under challenging conditions. On the far side of the garden, they are particularly exposed to sun, wind and rain. This is something that you need to consider when selecting plants — among other things.

From the ground up — the right flooring

Regardless of your design preferences and your favourite material, the floor on a roof terrace must have certain properties that make life easier for you and your plants. It should be hard-wearing and able to cope with you placing and moving heavy pots on it. It is also important for the floor to be waterproof so that no moisture seeps down into it and potentially causes serious water damage. Ideally, the floor should be slightly inclined so that rain and other liquids quickly run off into a gutter at the edge or into a drain.

And don't forget the structure. After all, a substantial amount of weight can quickly build up on a roof terrace due to the various plants and flower pots, planters and flower boxes. The substructure must be able to support and withstand this weight. We also particularly recommend fitting a practical water connection.

Planting your roof terrace — your charges need to survive in this environment

Life on a roof terrace or in a roof garden is tough for plants. After all, there are certain things that you expect from them given the location. Blazing sun, heavy rain, the freezing cold, strong winds
— they have to brave all this while still looking good. If you pick the wrong candidates then you will soon be pulling your hair out over bent, frozen, withered or drowned flowers. In the worst-case scenario, you will find that you need to replace or at least replenish the vegetation every season. This will frustrate you — and, of course, cost you money.

Ideally, you should therefore put a few safety measures in place for your fosterlings. Only plant them in containers that have a drain hole, for example. Avoid using mats as far as possible. This is because if there is a longer period of heavy rain, the water will collect in the container and cause waterlogging. Nevertheless, you do need to water certain plants regularly and diligently — possibly even several times a day, depending on the weather.

To prevent plants from quickly drying out, create a wind shield for delicate plants — either using artificial material or other, taller plants. During the winter, plants that are sensitive to frost need a suitable pot or planter and insulation made from reed, raffia mats, bubble wrap or a similar material. Otherwise, you will need to set up winter quarters for them. Weight is also a factor to consider when transporting the plants to their new home.

Although it may seem like it now — there are few limitations when it comes to adding greenery to your roof terrace. Many plants are virtually made for life in the clouds.

This is where you can get stuck in

If you are wanting to design a roof terrace, then you should ensure that there is plenty of floral variety. In other words, variety is the spice of life. Positioned correctly, short, tall, narrow and wide plants can bring much pleasure on the upper deck thanks to the attractive variety on show. Promising applicants include ornamental grasses, groundcover, creeping plants, shrubbery and small potted trees. Below is a selection of ten suitable plants:

  • Thuja species are available in many forms. As a hedge, for example, they are ideal as privacy or wind protection. They protect you from prying eyes and offer shade to other plants, preventing them from drying out. The hardy thuja needs a very large container. As a rule of thumb, 40 cm in diameter per 100 cm in height
  • A cactus of the Echinocereus triglochidiatus species needs expanded clay or coarse gravel in the pot for drainage, with a mat on top of this which is then covered by the soil. This enables the cactus to brave the elements, even in the rainy winter months. It is even better, however, if you can place the cactus under a table or equip it with a light and air-permeable cover.
  • There are 400 species of sedum, and they can reach a height of up to 70 cm, although there are also carpet-forming varieties that are particularly well suited to roof terraces. They withstand dry periods well and should not be watered too much.
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  • Ivy is also a potentially welcome guest in your green oasis. This expert climber can be easily guided in the direction you want it to grow and, if grown on a fence, provides privacy and wind protection. It is green all year round, leads a shadowy existence in a pot but copes well with the sun and knows to overwinter. We do still recommend wrapping it in an insulating layer. It doesn't need much care and attention, but should be trimmed at the right time if it starts to grow out of control.
  • Bamboo is also a good candidate for privacy and wind protection because it grows to some height (up to 2.20 m). It needs roomy pots with bamboo soil and likes to be fertilised regularly. Incidentally, the Fargesia rufa species can survive temperatures as low as -26°C.
  • Sage has proven to be fussy when it comes to location and prefers facing west/south. The herb also likes it warm and sunny. In terms of soil in a medium-depth pot, it just needs a low-nutrient, permeable soil. It does not cope well with waterlogging or heavy frost. As a precaution, sage should therefore be provided with heat insulation or moved to winter quarters.
  • Prostrate rosemary is also one of those herbs that tends to grow flat and reaches a height of up to 20 cm. It needs a lot of water, but does not like being waterlogged. Like sage, it is generally a hardy plant, but if in doubt then it would be happy to have some warm insulation. It originally comes from the Mediterranean region and is therefore used to the sun and somewhat milder temperatures. Using too much fertiliser on this plant will cause mildew to attack — a fate that it also shares with sage.
  • Boxwood is an evergreen, adaptable plant and is an ideal candidate for adding a bit of greenery and style to your roof terrace. As long as it is trimmed when required, boxwood works equally well as a hedge or as a solo piece. Beyond that, boxwood is not bothered about its location. However, if the sunlight is too strong then this can damage its leaves. An indigenous plant, it is used to the cold in the wild but likes an insulating layer, made out of jute or similar, when potted. Please note: Its leaves tend to dry out when exposed to strong sunlight in the winter.
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  • You can use shrubs to plant your roof terrace as long as you pick robust varieties such as lavender, baby's-breath or cotton lavender. These shrubs cope well even at higher temperatures and rarely come to grief in the winter. It's a different story with plants such as tulips and daffodils when potted, though. They quickly expire in minus temperatures.
  • Ornamental grasses are also a good choice for your oasis. There are overhanging varieties such as fountain grass, evergreen varieties such as sedge, and delicate fescue. Most varieties are very undemanding and don't need fertilisation or much water. Slugs and other pests usually steer clear of them. The smaller varieties also tolerate other plants well (aster, chrysanthemums, echinacea)