The following article is written by Andre Swart.
Portulacaria afra (Porkbush) or “Spekboom“ as we all know it , is one of my favourite specimens to work with. My collection and my knowledge of these incredible tolerant species has grown over the last 15 years. This popular succulent plant is found on rocky slopes in the Karoo scrub and semi-arid landscapes in the eastern parts of South Africa. The word “afra” is in reference to the fact that the plant occurs in Africa.
Portulacaria afra is also known as: Elephant's Food (English); Olifantskos (Afrikaans) and for some also known as “small leaf jade” and “dwarf jade." It has shorter internodes and much smaller leaves than Crassula varieties. However, both species are often referred to by the common name of jade. But there is this confusion regarding identification. Some will refer to Portulacaria afra as a “Dwarf Jade Tree“ well Portulacaria afra is not a jade plant. It is a common name what most Americans and Europeans will call it BUT Jade is Crassula ovata, a completely different Family, Genus and Species.
Image caption: Crassula ovata” jade plant.” The leaves are more elongated (ovata = "egg-shaped") and larger than Portulacaria afra. Also, they are missing the indentation at the tip that makes Portulacaria afra leaves heart-shaped. The growth of Crassula is "stockier" and the branches are smooth (not flaky as P.a).
Portulacaria afra is much easier to develop as a good bonsai than the larger leaf jade plant, Crassula. Young branches and trunk are reddish brown, when they mature they become grayish in color. The leaves are close together, opposite and just under 1cm long -- when grown in the sun.
There are other species of Portulacaria (8 species known) which will not be suitable for bonsai, for example:
Image caption: Portulacaria armiana is one of three Portulacaria species in South Africa and native to Namibia, easily distinguished by its large cotyledon-like grey-green leaves and tall perennial whipstick-like inflorescence.
Portulacaria pygmaea is a dwarf succulent type of shrub with small, thickly fleshy, grey green leaves and occurs on rocky hillsides in Namaqualand, South Africa and is also not suited to bonsai cultivation.
There are people that will say “Spekboom “ is a succulent, not a tree and not real bonsai material. Then those haven’t been to the Karoo on a field trip, in certain places they are 4-5 meter proper trees with nebari (like a ficus) and trunks thicker than an average human body.
Image caption: The size of these trunks is what we all dream about. Some will argue, no “shari” or “jin” as this will invite disease, but nature will prove us wrong again!
If you can get a proper and believable tree image out of it, why not use it? But do not grow it like a shrub, be creative and develop the branch structure with empty spaces. I believe it is underutilised in our country, so I think we need to make more use of our indigenous species.
Image caption: Andre Swart with one of his Portulacaria Afra grown over 9 years. The loose wire on the back lower branch is to support extended growth to the left in future as per design.
Do not train your tree like a shrub, you have to see the branch structure by creating empty spaces. Trim your spekboom bonsai into a tree shape by removing branches and leaves that clutter the style you desire.
Image caption: Pruning – (Clump style) Define the stems you want to develop into branches by nipping off leaves and leaf buds along the stems , along the underside of branches. Remove large leaves to open the plant and allow light to reach inner stems where you want new, smaller leaves to grow.
Make cuts clean and allow cuts to air dry and callus over naturally, do not use sealer as it is not necessary and will only invite disease underneath the sealer. Portulacaria has very thin cambium so the wound will not be overgrown like other species.
Image caption: Cut back twigs to only 2-3 nodes and use the “clip and grow“ method to improve the ramification as this works the best on these specimens. If you are building structure, wait until the “reddish“ stem hardens off to a “greyish“ colour before your cut back hard to the direction of the new branch.
They store more water in their branches than most trees, so they take much longer to lignify (harden, turn from green to gray), so for these reasons it is difficult to successfully train these with wire, but not impossible. Wiring is to keep the thicker branches in place and wire “loosely." Watch out for “wire bite“ but fortunately once the wire is removed, the branch will bulge back without disfigurement because of the water content in the branches. These “wire bites“ can sometimes contribute to the character of the tree. The same as when you want taper, to then scar the main stem or branch with a very sharp clean blade and let nature takes its course with creating a naturalistic looking scar. Obviously “shari“ is not ideal, as it just invites disease but it can work in the right setting with proper after care, but not many will agree with me!
Training a spekboom in a literati style, that’s a challenge because of its heavy foliage but with proper care the leaves can be reduced by pinching to only 4-5mm big.
Prune heavily in the spring and summer, but then also anytime when there is active growth pending where you are and your micro climate. I use the “hedge cut“ method for the first 2 growing seasons to develop the canopy, then cut back hard and then to go into the structure with scissors to identify the branches you want to keep and to remove all the unnecessary growth that will interfere with the desired result. Use sharp scissors and remember to leave a bit of “stalk“ which you later can rub off. Do NOT use knob cutters!
Spekboom bonsai should be watered more often in summer and less in the winter. Let the soil dry between waterings, but then here it depends on your growing medium. Your bonsai mix depends on where you live, your climate, your watering routine etc. There is no one “best” mix. You have to figure out some of those requirements for your microclimate and then decide which is the best mix. Do not use any fine particles or soil, the mix must be loose. If you have a well drained mix, then it is unlikely you will end up with root rot because it is usually not over watering but poor, compacted soil that will deprive your tree of oxygen and lead to the demise of your tree. I use about 70% grit/crushed stone and 30% composted pine bark, and I water my spekboom collection almost everyday. In the winter give enough water to keep the leaves from shriveling.
If an overwatered tree is the problem, remove the tree from the pot and change the soil, as this invites fungal rot disease When you remove the saturated soil from the roots of your tree, be gentle as those roots are very delicate! Cut away roots that look weak and suspicious. Refill the pot with fresh, an almost loose , gritty mix and important to position your spekboom to its original growing position not to further stress the tree. If your tree is drooping branches that touch the side of the container or the soil, you'll likely have to cut it back to save the rest of the plant. So use sharp scissors to cut the section where it meets the main part of the stem.
Spekboom is easily propagated from cuttings or truncheons. Cuttings can be allowed to dry out for at least a week in a cool place and then planted in washed river sand. It will root easily and can even then be planted directly into the ground, but do not water them straight away.
Image caption: Sometimes cuttings will develop roots, even lying on the surface if they are misted regularly.
Image caption: Water sparingly so that the potting mixture is only damp, but I prefer to give them a twice daily misting on the leaves only, until the cutting takes root. Keep them in a warm shady position until those shrivelled leaves start pushing out new and luscious green leaves after about 1 -2 weeks.
Environmental factors such as temperature and humidity affect the speed at which the roots and new plant develop. Even very large Yamadori can be treated like this. Portulacaria afra needs less frequent watering during its dormancy period, but because the leaves on Portulacaria afra are so thin, it can handle more frequent waterings than other succulents.
Image caption: Make a clean cut at the roots and wait at least 2 weeks for the wound to callus over before you plant the tree in a container. Do not worry about those shrivelled leaves. Tie down the tree or support it with a rock as the foliage is so heavy it will tumble the tree over and break all the new delicate fleshy roots.
Portulacaria use their fleshy leaves and branches as reservoirs. They can survive in relatively small amounts of soil and like to be almost dry out between waterings.
Image caption: Portulacaria can grow in very little growing medium and with regular pruning and care, the leaves can get smaller and the tree can even evolve in a literati style.
Spekboom do well when fertilized with organic fertilizers, or those organic pellets in abundance on the surface (or even inorganic, a few 2:3:2 granules in used tea bags just below the surface at the rim of the pot) will let them grow like crazy, so you have to keep up with pruning right through the active growing season, which here in George, Southern Cape, is almost throughout the year. With fertilizer they can push growth and if left in the sun, they need very little care. With frequent pruning, the small leaves readily form desirable pads. They can survive for a while indoors but when they drop leaves it is time to move them out again, however I will not recommend indoors except when you exhibit.
Image caption: Thick cuttings can lend themselves to develop Shohin or Mame Bonsai in proper ceramic containers, or in creative designed cement containers. Their root system does not mind the leaching over time.
The only way to thicken the trunk is to put them in bigger pots and to grow them outside as much as possible, try against a northern faced wall and aim for root zone warmth. Add rocks or stone to the mix - try simulate the conditions in the Karoo!
Image caption: For example, fix the cuttings in an open plastic cooldrink bottle with riversand and fill up the top with 13 – 17mm stone. Tie down the larger truncheons with wire or anchor pillars or tie against a rock for support for a few years!
Spekboom Bonsai prefer ‘tight feet’ and can go years without root pruning. Light root trimming is effective, however when necessary, drastic root pruning is not harmful. Allow the soil to become dry before repotting and DO NOT WATER the plant immediately after potting. The existing leaves may even shrivel before new leaves appear. This is not a problem. If some of the old leaves drop, they will quickly be replaced.
Image caption: Root-over-rock ”group planting” is an excellent style for Portulacaria. The roots readily establish in small pockets of soil and the exposed roots thicken and age surprising well. The plant must be tightly secured on the rock to get it started.
Image caption: A Portulacaria “Raft style“ developed from a truncheon that fell on the ground years ago.
Even in their native habitat, the plants need to be very mature before they form flowers. Getting the plant to bloom will require you to keep it in a dry location, withhold water, and expose it to cooler nighttime temperatures. Given the right setting and environment, a spekboom plant not flowering, may simply be that it is not old enough to reproduce yet. Only recently one of mine flowered for the first time in 13 years!
Did you know that the leaves of the Spekboom can be eaten and have a sour flavour (like a Granny Smith apple) It is heavily browsed by game and domestic stock and highly favoured by tortoises. Traditional uses also include the increasing of breast milk by lactating mothers. The leaves are used to quench thirst, so try sucking a leaf next time you work on your Bonsai. The juice is also used as an antiseptic and as a treatment for sunburn. Farmers will tell you that a small sprig of Porkbush steamed with a tomato bredie (stew) imparts a delicious flavour. Try it!
I have been doing Bonsai for more than 25 years and Portulacaria is one of my favourite trees to work with, yes, for me it, is a tree. My wife and I will go on frequent visits to farms of patients of mine in the Karoo and with consent, we have the opportunity to collect some really old specimens.
To acquire the best Yamadori on these rocky slopes, you need medical insurance (It's dangerous!), abseiling skills and the proper equipment and technique. Do not take out if you do not have a plan for developing it into a proper bonsai. Decide there and then beforehand what you are going to do with that tree, draw it, ponder over the idea and share the idea with the farmer in respect to the tree in its arid environment. Take the usual care as for cuttings like described before, try to save those delicate roots and make clean cuts. Photograph your Yamadori and send a photo later of the near finish product to the farmer, he will appreciate his contribution to your collection!
My signature Portulacaria afra tree comes from this slope 9 years ago….but there are always easier ways to collect Yamadori.
So, I hope that more people will see the potential of Portulacaria Afra and that the “Spekboom “ as an indigenous species will gain respect as a proper tree represented in different styles in our Bonsai Collection.
Andre Swart is Paediatrician in Private Practice in George. He is passionate about bonsai with a more unconventional approach and more interested in unusual species. The artistic and horticultural approach he shares with his wife, Isabel, who is a keen gardener. You can contact him via email email@example.com