Callistemon update

A couple of weeks ago I showed you how I repotted my Callistemon sieberii bonsai.

Despite removing quite a lot of roots this tree has just continued to grow without any apparent setback. The shoots that were left intact have continued to grow and will need trimming soon.

 

 

 

New buds have formed from the leaf axils on all shoots that were trimmed.

 

 

 

 

New buds have also emerged from older, bare wood on the branches

 

 

 

 

and even on much older areas. These are near the base of the trunk.

 

 

 

 

I think you can see here that summer repotting seems to suit these trees.

You may also recall that this tree went back to its normal display space, in full sun, straight after repotting. Since then we’ve had a few really hot days, some rain and some cooler than normal days. I have not found that trees need extra protection or shade after repotting. In my experience, bonsai seem to do better after repotting if they are placed somewhere similar to the area they are used to. Adequate sunlight helps the tree recover from both root and shoot reduction.

Banksias as bonsai

Summer has proved to be a good time to repot banksias and a couple of the shibui bonsai banksias were due for it this year.

When I first started to grow banksias for bonsai they were not very successful. Most just lasted a year or two then suddenly died. Given that banksias have a reputation for being quite sensitive I just thought the genus was not suitable then I started to see some great banksia bonsai and gradually pieced together a couple of important facts about banksia bonsai.

Banksias in pots do need fertiliser. Much of the literature warns to be very careful with fertiliser near banksias because they are phosphorus sensitive and can die if fertilised with the wrong thing so being unsure what fertilisers were suitable I was not feeding them. I’m certain that a number of my experimental trees died of starvation before I discovered the truth. Banksias do develop proteoid roots that help them accumulate scarce phosphorus from the depleted soils where they grow but they only grow these proteoid roots when they are starved of nutrients. Some experimental work with the closely related South African proteas showed that if they are given fertiliser containing phosphorus from an early age or are introduced to it gradually the proteoid roots disappear and the plants are then able to tolerate higher levels of phosphate in the soil. Now I make sure I feed my banksias well like all my other bonsai and they are happy to take the same fertilisers as the rest of my trees. Many of my banksias are now are potted into mix containing standard osmocote rather than worrying about special low P ‘native’ fertiliser.

Quite a few of my earlier banksias died suddenly in late spring and summer. When I investigated the roots I discovered that the pots were usually crammed with very fine roots and, while the outside of the root ball was damp, the insides were bone dry. These trees died from dehydration despite being regularly watered. Banksias seem to quickly fill the pot with masses of very fine feeder roots to the stage where water cannot penetrate into the centre of the pot. Regular repotting seems to have eliminated this problem and now I try to root prune young, vigorous banksias each year to allow space for water during the summer.

Some early information about native plants as bonsai showed that most seem to prefer to be root pruned and repotted in the warmer months. Some experiments carried out here at Shibui Bonsai confirmed that banksias in particular do not tolerate root pruning well in the cooler months but thrive when roots are cut when it is warm. It does not seem to matter what growth stage the trees are at. I have root pruned banksias covered in fresh, actively growing new shoots and they continued to grow afterward. Usually I prune the trees to remove most of the soft new shoots but that does not seem to be absolutely necessary.

During the growing phase banksias can just be slip potted into larger pots. Because they have few larger roots that can get tangled up there’s not really any need to do a full root prune on growing trees. Simply turn the tree out of its smaller pot, place the root ball intact into a larger pot and fill the spaces with new mix. I even do this when planting banksias into the grow beds and have not had any problems with tangled larger roots when they are dug several years later.

When repotting I find that the masses of fine banksia roots are very densely tangled and are difficult to cut with traditional root shears. The roots are, however, quite brittle. Simply grabbing a handful of the root ball at a time and pulling will quickly reduce the root mass enough to repot successfully. When dealing with larger pots an old saw is useful. Simply saw through the root ball at a suitable depth to reduce the root mass. Sometimes I’ve even sawed off chunks around the edges to complete the root reduction before potting the tree back into fresh mix.

Here are some pictures of the banksias I repotted on January 1st 2018

Banksia serrata. This one has been grown in a pot for around 5 years. I have found that banksias thicken quite well, even in relatively small pots.

 

 

after pruning

 

 

 

 

 

 

 

 

 

root ball before root pruning

 

proteoid roots

 

 

 

 

 

 

Proteoid roots. This one must have been getting a bit hungry. It has developed quite a lot of these proteoid roots to try to scrounge as much P as possible. fertilising this one with high P fertiliser would have made it quite sick and may even have killed it.

 

 

after root pruning

 

After root pruning most of the proteoid roots are gone so thus tree can now have normal fertiliser again.

Note that there are no larger roots visible. Banksias seem to rely mostly on the masses of fine feeder roots.

 

You can see that I routinely remove around half the root mass at repotting.

 

Banksia marginata.

root damage caused by curl grubs

Curl grubs seem to like banksia roots. As soon as I removed this one from the pot I could see that something had been feasting on the roots

Luckily the damage is not too bad. I probably would have cut off nearly that much anyway.

 

 

The culprits!

My turkeys really enjoyed helping me dispose of the grubs.

 

 

 

 

 

 

Banksia marginata – before

Banksia marginata. No curl grubs this time but I thought this one was ready to go into a bonsai pot for final development of branches and ramification.

after pruning, root reduction and potting

 

Repotting Callistemon

Today is the last day of 2017 which means it is well into summer at Shibui Bonsai and that means it is time for repotting some of the bonsai.

Last week I gave my Callistemon its annual after flowering prune. This one is Callistemon sieberii – River bottlebrush which flowers later than most Callistemon species, normally Early-mid December here.

Continue reading

More pine cuttings

Some say it cannot be done…..

Here at Shibui Bonsai I’ve often found that much of what ‘they’ tell us is not completely true so I’m often putting aspects of bonsai wisdom to the test.

Pine seed is currently very difficult to obtain here in Australia so many growers are looking for alternative ways to propagate pines for bonsai so even though the ‘experts’ tell us it cannot be done I’m trying to grow more pines as cuttings. Continue reading

Pot up some pines

Most of the trident maples now have tiny pink buds where new leaves are emerging to show that spring has arrived at Shibui Bonsai.

I’ve repotted most of the deciduous trees that need doing this year so it is time to move on to the evergreens. Some growers now repot pines in autumn but I’m still doing most of mine at the traditional spring repot time.

Today it was time to get a few pines into their first bonsai pots.

This twin trunk Japanese Black Pine has been developing slowly over the past 15 years or so. It has an impressive nebari and some well placed branches and now it is time to start developing better ramification. I think the restricted space in the smaller pot should help control the new growth and help the process.

Black pine after root pruning

 

 

 

 

 

 

 

 

nebari

 

 

 

 

 

Among the roots lies a clue to the origins of this tree.

This is one of the pines mentioned in the previous post. Seedlings were threaded through a hole in stainless steel disks to see if pines could be developed in a similar way to the maples as outlined in previous posts. Pines do not root quite as well as maples and only 2 out of 5 survived the process but the experiment did prove that it can be done.

In this case I put 2 seedlings through the same hole. In the process of growing new roots they have fused into a single twin trunk tree.

the steel disc

 

 

 

 

 

 

 

 

I’ve selected a round drum pot which has adequate size for a developing tree but still a reasonable match to the tree.

Now we wait until December for the first round of candle pruning to start the process of developing branches with full ramification.

Trident nebari

Spreading basal roots, known by the Japanese term ‘nebari’ is considered very important for maple bonsai. Surface roots are prominent features of old maples, pines and elms so these features are also valued in bonsai of these species.

Nebari should, ideally, spread evenly all around the base of the tree, showing enough to give the tree the air of age and stability. Continue reading