"Shrub trees"

Consider training a shrub into a small tree.
Sunday, 11 October 2020     

Loropetalum chinense trained as a small tree

As gardens become more compact, the idea of including a tree in them becomes problematic, as there is a limited palette of suitable trees that actually stay small. I feel gardens need at least one tree to give height, proportion and a sense of permanence. And the shade of a tree in part of the garden provides shelter for some of the many beautiful plants that thrive away from the harsh rays of the sun. On solution is to train a tall shrub by removing the lower side branches flush with the main trunk as it grows so that it takes on the appearance of a tree. I find this look more appealing than a ponderous dome or oval of foliage all the way to the ground, and it also creates space beneath the canopy to grow small shrubs, perennials or groundcovers, either directly planted into the ground or in pots. Whilst the training is best done as the shrub grows, it is also possible to 'lift' the canopy of a mature shrub, even if it by then has developed multiple trunks.

The shape of the canopy can be left as a casual mop or else clipped into a more formal shape such as a cloud or an umbrella. A number of shrubs lend themselves to this sort of treatment. My first attempt was with a purple-foliaged Loropetalum chinense (pictured at the start of the blog). The removal of the lower branches immediately gave it more presence in the garden and I underplanted it with various rhizomatous Begonia, bromeliads and Iris japonica, all perennials that can grow in a shallow stratum of soil. The Loropetalum is clipped over into a sort of mushroom shape after flowering every year.

My next subject was a tall species of Rhaphiolepis indica shrub, which I trained from a young plant. I was surprised how high and wide this shrub can get if allowed to grow naturally (unlike most of the modern cultivars of Rhaphiolepis) and I simply didn't have the space for its normal girth. After only a few years, it now really looks quite like a small tree and flowers happily high above the plants sheltering below.

A golden-leaved form of Duranta erecta called 'Sheena's Gold' was the next shrub to get the treatment . It was a fairly old plant by the time it was pruned and had multiple stems, but I think this can actually add a quirky dimension to the final result. This is pruned into an umbrella shape and I have recently underplanted it with some tufts of gold-foliage Acorus gramineus 'Ogon' , which will tolerate shade, and will soon add in some Sedum mexicanum 'Gold Mound'.

The angel trumpet - Brugmansia species - is a good shrub to train to a single trunk as it can be a fairly untidy-looking shrub. It is also possible to grow such a 'tree' in a large pot. It can be pruned very hard in late winter to keep its canopy under control. There are various species and cultivars with single and double flowers in hues of white, yellow, apricot and pink. They have flushes of blooms throughout the year and provide a wonderful spectacle when the branches are smothered in the enormous trumpet flowers.

Camellias are also classic shrubs that can be converted into small trees in this way. Sasanqua camellias are possibly the most suitable, as they have a more open, willowy structure than Camellia japonica. Reticulata and miniature-flowered Camellia are also amenable to the treatment. They are excellent for part-shaded spots in the garden and by removing the lower branches, other plants can be grown to add to the scene when they are in bloom, such as snowflakes, forget-me-nots, primulas and hellebores for the reticulata and minature-flowered camellias and Streptocarpus hybrids , shrubby Begonia, Japanese anemones and any of the numerous easy-to-grow and attractive Plectranthus species and cultivars for the sasanqua camellias.

My most recent shrub tree has been created from Elaeagnus x submacrophylla 'Silverberry', (ht 2-3 m, previously known as Elaeagnus x ebbingei 'Silverberry'). Sometimes called oleaster, it is a most obliging shrub that will grow in heavy or part shade or full sun! It has attractive dusty green leaves (which have a delightful silvery sheen in spring) with a silvery underside, and has a dense, upright form. Inconspicuous perfumed flowers appear in late summer and autumn. It is drought tolerant once established. Now that it looks more like a small tree, I have underplanted it with silvery Plectranthus argentatus, to echo its tints.

Other potential subjects for shrub trees include Viburnum tinus (laurustinus), Syzygium species and cultivars (lilly pillies), Murraya paniculata (orange jessamine), Photinia cultivars, Rondeletia amoena, Tibouchina lepidota, Justicia adhatoda and Euonymus japonica cultivars. I'd love to hear of other pruning experiments gardeners may have made with shrubs.

 Reader Comments

1/8  Margaret - 2122 (Zone:10 - Warm Temperate) Monday, 12 October 2020

Agree with your idea of training shrubs as trees. My garden is small, and I have had success in keeping a crepe myrtle contained, a peach brugmansia as a standard, giving shade to some rhizome begonias. My virburnum (snowball), conveniently shed some branches, reducing height, providing shelter for begonias and hostas in pots. As you remarked underplanting is a good way to provide interest, if you wish to hide bare trunks. They all sound great, Margaret. It does provide scope for underplanting, if they are trained as small trees. Deirdre

2/8  Bren - 2540 (Zone:10 - Warm Temperate) Monday, 12 October 2020

Interesting blog! I have started to do the same thing with some big old azaleas in my garden. I got the idea from the fernery in the Sydney Botanic Gardens where there is an absolutely beautiful azalea tree. In the past I would never have bothered with such an idea, preferring the natural look, but now I will look at some of the other shrubs I have (such as Duranta) to see if I can also shape them! That azalea tree sounds interesting. I must pay another visit to that wonderful fernery! Deirdre

3/8  Margo - 2154 (Zone:10 - Warm Temperate) Monday, 12 October 2020

What a great idea for smaller suburban gardens! Thanks Deirdre, I have two recently planted orange jessamine from tubestock that unbeknownst to them, are now destined to be TREES when they grow up! Hope it all goes well, Margo!! Deirdre

4/8  Kerrie - 2104 (Zone:10 - Warm Temperate) Monday, 12 October 2020

Good idea Dierdre & I actually do this with my beloved Brugmansias I have in pots. Wish I could add a photo to the comments as they are magnificent! They must be marvellous, Kerrie. Deirdre

5/8  Christine - 2429 (Zone:10 - Warm Temperate) Monday, 12 October 2020

Great and timely article for me, Deirdre, as we have downsized twice in the last 6 yrs!!! Training a golden flowered Angels Trumpet in a large pot at the moment ( cutting from last large country garden...), and working on a couple of sasanqua camellias. A red Diamonds in the Dark crepe myrtle will fit the bill too,....smaller than the most common cultivars and more cylindrical. Love your posts. All great ideas, Christine. Thank you. Deirdre

6/8  Lynette - 2577 (Zone:8-9 - Cool Temperate to Alpine) Wednesday, 14 October 2020

I too have done it with a large old sasanqua camellia which grew to the ground: 'Weeping Robyn, 2 acacia cognata' Limelight' , and many sasanqua camellias into balls on sticks . All are now features in my southern highlands garden allowing ground cover to grow happily underneath . Sounds so nice, Lynette! Deirdre

7/8  Lynne - 2479 (Zone:11A - Sub-tropical) Wednesday, 14 October 2020

I have done this with a Crepe Myrtle successfully as I wanted to keep it but it became too bushy and blocked a rather lovely view of the rest of the garden. I don't mind looking through the bare trunks at all and it is rather effective. Never thought to try this on Azaleas and Camellia Sasanqua.....great idea! Yes I rather like trunks! They can be quite sculptural. Deirdre

8/8  Lynette - 2577 (Zone:8-9 - Cool Temperate to Alpine) Monday, 19 October 2020

Thanks Deidre. If you have a look at some of my pics on Instagram you will see what I mean. @lynspics1

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