Lavender Star Flower (Grewia)

I recently visited a bonsai nursery at the suggestion of a friend and promptly fell in love with this Grewia (not sure if occidentalis or caffra?). However, there doesn't seem to be as much info on it as other flowering bonsai. Like my bougainvillea thread, Im going to lay out what I've seen on it so far. Please feel free to correct anything or offer your own advice! Thanks.

Soil
The one source I found suggested 50% organic (potting mix or pine bark), 25% pumice, and 25% lava rock. I've also seen that iron deficiency (chlorosis) is a common problem, so additives may be necessary.

Fertilizing
Since the Grewia likes acidic soil, I was wondering if it was worth it to use azalea fertilizer. Alternatively, I've seen that Apple cider vinegar could be used to achieve the target 5.5 pH.

Watering
I've seen conflicting information on this one. Some say to soak through until water comes out the bottom and wait to water until the soil is dry. Others say to keep the soil moist, but never wet. Anyone with experience here?

Pruning
Flowers need to be pinched continuously on young trees to promote more growth. Trees can be pruned heavily, but Im not sure about the roots. Do those need to be pruned regularly, or do Grewias like to be more rootbound?

Roots
The one thing that really makes me nervous on this tree is the roots. There seems to be a clump of dried/dead roots near the base. They are very thin, and many are just hanging off, barely touching the soil. Do these need to be removed, and are the indicative of a larger problem?



Styling
The trunk has a rather interesting twist, which means there is a bright future as an informal upright. I plan to refine the triangular shape it already has, but would it look better if I allowed full growth along the branches, or isolated pads like I see on a lot of junipers?



Blue Leaves
I've noticed that a few of the leaves have some sort of blue residue on them. I was thinking it was from a fertilizer the nursery may have used, but I'm not sure. Any ideas?

Have no idea of where you are from your profile but did find this article that may be of some use in a general sense.
http://homeguides.sfgate.com/lavender-star-flower-care-60479.html
and this one:
http://www.bonsaitoolchest.com/download/lavender_star_flower.pdf
hope it helps.

armetisius said:

Have no idea of where you are from your profile but did find this article that may be of some use in a general sense.
http://homeguides.sfgate.com/lavender-star-flower-care-60479.html
and this one:
http://www.bonsaitoolchest.com/download/lavender_star_flower.pdf
hope it helps.

Click to expand...

Thanks armetisius. Those are the two main sources I've found so far and they've been a great help. I just wanted to see if anyone had personal experience with these, since this seems like a comparatively rare bonsai.

Cover the exposed roots with an inorganic mix, grow that way for a year and check them. If they are alive take more off the bottom and repot it deeper... The Blue film looks like Copper Fungicide which would make sense if the grower kept it damp. I use Fertilizer at 5 - 7 times dose and it never leaves a film but Copper always does. I do not know about that plant but those roots look like they can be developed as I described...

Grimmy

You're from OC, you get this from house of bonsai?
I have one, I see them grown as hedges. Azalea/acid mix is probably a great way to start with pumice and lava.
may need to be dug/root pruned annually.
If it were my tree, I'd slip into a larger, deeper container. plant deep in the container to continue lateral root growth and build flare at the trunk base. you'll want to remove all those dried up dead roots, no cause for concern unless the tree is looks unhealthy. bury the trunk base so that any live roots will aid in thickening the base.
wire young branches as they harden off.
cut back to several leaf pairs or a finer twig in fall to begin ramification when ready. cut spring growth back to one leaf pair and let new shoots extend as far as needed.
Strongly growing branches will dominate growth (sap suckers) and other areas may not elongate unless vigor is redistributed through selective pruning. I think this is pretty standard to hedge type like privet and boxwood; clip and grow.

Its definitely occidentalis. Very strong growers once they are established. They are from Africa (think Australia to). Saw them in the wild as "semi climbers". They use the other shrubs and bush to climb and grow as they go. They flower all summer long. Beautiful and very striking. The flower don't last long. I remove it with the bud after the first day. That helps it produce more over a longer period. Because they are natural "semi climbers" they tend to send out long shoots that can be difficult to contain. Well worth the effort as bonsai....

Here is some info about the plant .... http://www.plantzafrica.com/plantefg/grewiaoccident.htm

With all of the suggestions, it looks like a good idea to repot in a deeper pot for more trunk development and to let those upper roots to grow a bit more. Thanks for the advice!

Special thanks to Grimmy for the info on the copper fungicide.

And yes, aframe, I did get this one from House of Bonsai. I went to check out the class, but found out that I had come too late. Couldn't resist a new addition though.

I finally had time to repot my grewia yesterday. The weak exposed roots were really bothering me, so I ended up working into the wee hours to get it done before leaving for another week. The tree came right out of the pot with relative ease (as compared to my bougainvillea which took all of 20 minutes to tease out). The roots were much more dense than I anticipated, and I wasn't able to get much of the soil out. There was one very large taproot that circled the entire root ball. I pruned that and took a bit off of the bottom to encourage root growth a little higher.


I repotted in a mix of 60% house of bonsai potting soil (I didn't have time to get pine bark / peat moss / lava rock before leaving) and 40% pumice in a 14" shallow pot. I then fertilized with azalea fertilizer to add some acidity to the soil. I trimmed a bit around the sides to control some of the longer growth, but I'm not sure if it needs more at this point. None of the nodes had more than 2 branching points, and there were no upward / downward / crossing branches to correct. I'm thinking of pruning down the top growth, but a friend of mine advised against it until it thickened up a bit. I'm still trying to figure out how to approach the wiring (hence my thread in the General Discussion forum).

No wiring needed, just some TLC and growing for a season... Bonsai = slooooooooooooooooooooow

Grimmy

Yeah they like forming exposed roots. I ground layered mine to get rid of a huge exposed one. Mine usually takes two seasons after root work before it starts growing strong again. Man I love them in flower. Lasts the whole summer. Good luck on yours. Remember to keep it updated.....

Ive been seeing some yellowing on the leaves lately. At first i thought it was chlorosis, as Grewias tend to be vulnerable to iron deficiency, but the spotted pattern and eventual browning doesnt quite fit. Maybe fertilizer burn? Anyone have any ideas?

Mine does that to. I use to worry about it but not anymore. In its natural habitat its deciduous but in other locations around the world it's semi deciduous. Mine throws leaves all the time, and replaces it with new ones.... I'll get worried if it has more yellow than green leaves on it.

Has anyone experimented with using Kanuma to increase the PH on the grewia? According to Craig Coussins in his book Bonsai Master Class, Kanuma has a PH running 4.5 to 5. My soil is always running 6.5 to 7 and I tried to supplement with vinegar additive. I have not tried Miracid yet. I have read quite a few different soil mixes for this and not sure where to go on my first re-pot next spring. I noticed that there was evidence of granular fertilizer in this plant when I purchase it and can tell that akadama is in the soil mix which supposedly has a PH of 6.8. Just curious . . . . (I am a bonsai virgin. This is my first plant.)

I have my Grewia in plain old Boon mix with a little more akadama now. Previously ( 20 years ) it was in haydite and bark to no ill effect. It's much more vigorous now (5 years ) and liked the change. It is watered once a day normally and twice when it's hot. It's fertilized once a week with dyna-grow during the growing season. I prune it once a year in mid-February just before it starts to push new growth.. Wiring is done as the new the growth extends with 20 gauge wire. The ends of the wire are left long to accommodate the new growth as it keeps extending. These new extensions are zig-zaged to give movement and keep the foilage compact as the flower buds form at the end of the extensions. If you look closely at the photo you can see these wires. The wire can be removed in August as its "mostly" done extending.

Very nice tree. I have hopes that I can get mine there. Mine stays super wet after watering. I check it with both bamboo skewer and moisture meter. I will water once and not water again for at least 5 days. It is not looking too healthy right now. Yellowing leaves that are dropping. Looked so good when I first got it. I bought it at a nursery in Lexington. Right now I am on day 5 and still on the higher end of moist/lower end of wet with moisture meter. I know I over watered it when I first got it. We had a lot of rain from Irma for a few days so I couldn't get it outside, but had it in as much sun as we could get all day (moving it between two windows). Rain again yesterday, but sunny today so I am going to take it outside so it will dry out some. The PH is consistently running at high 6's to 7. My last watering was with rain water (which is all I use on both my trees) and some vinegar to try to get more acidity. Everybody says it likes to be at about 5.5 in what I have read. I am known as "Go Big, or Go Home" from my friends so naturally when I decided to do bonsai, I bought just about everything known to man for them. I have pretty much every kind of soil (Bonsai Mix, Kanuma, Lava, Pumice, Sphagnum Peat Moss, but no Akadama yet, its on the way), grow lights, tools, books, Miracid, Bio Gold, etc. Is the water retention a sign of being root bound? Should I try to re-pot in a better draining soil even though it is fall? I attached a picture of it with the moisture meter. Also I attached a picture of my juniper (takes water about every other day) which seems to be doing well and my two bonsai trees I made that I know I can't kill. LOL. Thanks so much for the response and good info.

It seems to me the your soil is too organic and retaining too much water and no air. I would wash whatever you have off the roots and put it into free drain inorganic mix.... 2 akadama, 1 pumice, 1 lava of similar sizes. I do not have a problem with PH. Store bought PH testers are totally inaccurate if that's what you're using. They always read between 6 and 7. You could experiment with Kanuma instead of Akadama since its known for higher acidity. I'm just telling you what works for me. I've never put Miracid on mine. Actually I did not know they liked lower PH. Hmmmm. PLEASE NOTE!!! If you are not able to water daily or more do not use the mix I described. You should not have a problem repotting this time of year with proper after care.

Awesome. Thanks so much. I have a mix of 1 Akadama, 1 Pumice, 1 Lava. Based on this I think I will supplement that with some Kanuma to get the ratio of 2 akadama/kanuma, 1 pumice, 1 lava. Since I am re-potting, do you think it would be a good idea to fertilize? I have Biogold Original cakes that is a 5.5, 6.5, 3.5. I just don't want to be one of those bonsai virgins who kills their first tree.

Kentucky Rick said:

Awesome. Thanks so much. I have a mix of 1 Akadama, 1 Pumice, 1 Lava. Based on this I think I will supplement that with some Kanuma to get the ratio of 2 akadama/kanuma, 1 pumice, 1 lava. Since I am re-potting, do you think it would be a good idea to fertilize? I have Biogold Original cakes that is a 5.5, 6.5, 3.5. I just don't want to be one of those bonsai virgins who kills their first tree.

Click to expand...

I think that is a good plan. I wouldn't fertilize for a month. Keep it in filtered sunlight for 2 weeks.

Will do. Thanks again for your help.