Upright-growing plants in pot

Think high! If you lack of floor space, favour plants which naturally grow upright. In this way you will create a green screen in a very contemporary setting, two effects in one!

The most upright plants, Horsetails
The Japanese Horsetail is a perfect plant to grow in a pot as it is neither draught nor harsh colds' sensitive. To water it, it is very simple: flood it permanently except in winter to avoid the pot splitting. A Horsetail screen is ideally obtained in a long planter, at least 15cm wide. Cut the unsightly stems in March when new shoots are appearing. You can also clip everything. If you grow Horsetails, combine them with Japanese Iris (Iris ensata) as they grow in the same conditions in pots. Their linear leaves and their big flowers perfectly suit contemporary landscapes!

A potted Japanese Horsetail.

The Japanese Iris is an ideal companion for pot-grown Horsetails.

A potted Fountain Grass.

Ornamental grasses, essential
From the Mexican feather grass (Stipa) up to the Fountain Grass (Pennisetum) not forgetting Bamboos even and including the Elephant grass (Miscanthus), ornamental Grasses offer a large range of vertical screens. In February-March, cut right back the ones which have dried out in winter. Give all of them some fertiliser at the beginning of the growing season, then once a month during summer, finally stopping the supply in September. Ornamental Grasses do like water, even the ones which are drought-resistant. They will be even more beautiful-looking if you install an automatic watering-system for them but watch out: do not flood them with water all the time.

As well as ornamental grasses, think about plants which have a similar shape but are not exactly ornamental grasses, such as the New Zealand Flax (Phormium), the Sedge (Carex), Cordylines, etc.

Column-shaped trees
Shrubs which naturally grow straight upright are not as numerous as the ones growing rounded-shaped but a few of them are really interesting to grow in pot. The most obvious is the Italian Cypress, perfect for hot, extremely sunny terraces, even if a little windy. Column- shaped trees (fastigiate) such as the Pyramid English Oak (Quercus robur fastigiata) or the Hornbeam fastigiate (Carpinus betulus fastigiata) take on the same shape with time. Give them a bit pot of at least 50L: they can reach 2m grown in pot, but rarely more.

Note that you can train a tree to grow as a column yourself, pruning it often, and this, as soon as the first year. But it requires a lot of work just like for topiary.

The climbers need to be well chosen
In the last category of upright-growing plants, creepers are the most common. Give them an important volume (from 3 to 50L at least). Species which have fine stems such as Clematis and Honeysuckles thrive better in pots than the ones forming woody stems such as Wisterias or Trumpet Vines. Train the stems on a wire taut along a wall, as a stake in a pot is not really stable enough when it goes over 1m in height.

Finally, the last tip: you can grow a climber to let it hang down: from a pot placed quite high, its stems will have a tendency to hang down forming a green-curtain!