5 trees for very small gardens: South African indigenous trees

Treeshop's clients frequently ask what are the best trees for a small garden? #smallgarden

This is a valid question, because you don't want to plant trees that will become a nuisance when they grow to mature size. They may, for example, damage your roof and foundations, lift paving or block your winter sun.

In this post I recommend 5 trees indigenous to South Africa that can be planted in a very small garden (or tiny garden) and not cause any problems in the future. The topic is covered as follows:

- What is a tiny garden?

- Trees vs. shrubs: How many choices do I have?

- 5 Trees for very small gardens

- About the author

1) What is a very small garden?

To decide when a garden is very small, I followed the guideline put forward by treebook.online, a website designed to recommend "fit-for-purpose" indigenous trees. TreeBook suggests that a very a small garden is about 25 square meter. This is the typical garden size of a two bedroom unit in a retirement village or townhouse complex, maybe in front of the lounge and main bedroom - about 8m across and 3 m deep.

2) Trees vs. shrubs: How many choices do I have?

Meg Coats Palgrave, probably the most authoritative book on Southern African trees, neither defines what is meant by "tree", nor "shrub". Smaller species are often described as a "shrub or small tree", or a "shrub to large tree". Clearly the terms "shrub" and "tree" refer to the appearance of a species. For a given species this may vary significantly. These two terms play no role in a species' botanical classification.

The Oxford dictionary defines shrub as "a woody plant which is smaller than a tree and has several main stems arising at or near the ground" and tree as "a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at some distance from the ground".

It is true that some trees have a tendency to grow multi-stem, giving them a shrub-like appearance. Sometimes such tendency is stronger when the tree is young. Growth form can be controlled by pruning. Often, when multi stemming is not controlled, the tree develops a beautiful dense canopy, which it would otherwise not do. By the same token, a tree which has a tendency to grow single stem can be pruned to grow multi stem, thus appearing shrubby.

Henceforth I will only talk about trees, but will indicate when a tree has a tendency to grow multi-stem. I will also indicate the tree's likely response to pruning.

Regarding the number of trees suitable for very small gardens: At the date of writing this post I have identified no less than 20 candidates. They will be discussed in a series of blog posts, 5 at a time. The series will be called "Trees for very small gardens".

3) The first 5 Indigenous tree candidates (English name, Afrikaans name, Scientific name) are:

a) Bushveld gardenia, Bosveldkatjiepiering, Gardenia volkensii

b) Bladder-nut, Swartbas, Diospyros whyteana

c) Big num-Num, Grootnoemoem, Carissa macrocarpa

d) Transvaal milkplum, Stamvrug, Englerophytum magalismontanum

e) Small-leaved dragon tree, Kleinblaardrakeboom, Dracaena mannii

I summarize below key characteristics of the above species, bullet point style, and provide a link to a Treeshop web page where you will find more information:

3.1) Bushveld gardenia (Gardenia volkensii)

Image: With permission from TreeBook

Gardenia volkensii key attributes:

• Mature size in a garden setting, 3m

• Growth form is compact upright

• Growth rate slow to medium

• Hardy, tolerates temperatures as low as -4 degrees Celsius

• Non-aggressive roots

• Well-drained, sandy soil

• Deciduous but not messy

• Requires modest water in summer. Water wise in winter.

• Responds well to pruning.

• Striking fruit stays on the tree for a long time

• Beautiful, fragrant flowers last only one day

• Bright green leaves bud early September

• Read more

3.2) Bladder-nut (Diospyros whyteana)

Image: With permission from TreeBook

Diospyros whyteana key features

• Mature size in a garden setting, 3m

• Growth form is bushy

• Growth rate slow to medium

• Slightly frost sensitive, temperatures up to -2 degrees Celsius

• Non-aggressive roots

• Well-drained, sandy soil

• Evergreen and not messy

• Requires modest water year round

• Responds well to pruning.

• Striking, large, bladder-like fruit stays on the tree for a long time

• Inconspicuous flowers

• Shiny, dark green leaves

• Read more

3.3) Big num-num (Carissa macrocarpa)

Image: With permission from TreeBook

Carissa macrocarpa key attributes

• Mature size in a garden setting, 2m

• Growth form is bushy

• Growth rate is medium

• Slightly frost sensitive, tolerates temperatures up to -2 degrees Celsius

• Non-aggressive roots

• Well-drained, sandy soil

• Evergreen and not messy

• Requires modest water year round

• Responds well to pruning and can be pruned into any formal shape

• Large, red, edible fruit attract many birds species

• White, fragrant flowers attracts insects

• Dark green leaves and fork-shaped spines

• Read more

3.4 Transvaal milkplum (Engleropytum magalismontanum)

Image: With permission from TreeBook

Englerophytum magalismontanum key attibutes:

• Mature size in a garden setting, 3m

• Growth form is compact upright

• Growth rate slow to medium

• Slightly frost sensitive, tolerates temperatures to -2 degrees Celsius

• Non-aggressive roots

• Well-drained, sandy soil

• Evergreen

• Requires modest water

• Responds well to pruning

• Striking, edible fruit (female trees only)

• Young leaves have a striking russet brown color.

• Read more

3.5) Small-leaved dragon tree (Dracaena mannii)

Image: With permission from TreeBook

Dracaena mannii key attributes

• Mature size in a garden setting, 3m

• Growth form is informal, spreading and upright

• Growth rate slow to medium

• Frost sensitive, only suitable for temperatures above -0.5 degrees Celsius

• Moderately aggressive, tuberous roots. Take some precautions

• Well-drained, compost rich, sandy soil

• Evergreen and not messy

• Requires modest water year round

• Tendency to grow multi-stem. Responds well to pruning

• Striking flowers and fruit. The latter remains on the tree for a long time

• Bright green, oblong leaves give the tree a unique appearance

• Read more

4) About the author

Dr. Piet Stoker a CALTECH graduate, is an emeritus Professor of Engineering. He has been cultivating indigenous trees for the past 15 years and was privileged to go on many trips in search of scarce and unique Southern African tree species. He is currently researching new ways to cultivate and grow some of these species. He is the author of TreeBook, an on-line tool to research "fit-for-purpose" trees indigenous to Southern Africa.