Hoya mindorensis problems

This is one of the Hoyas I got earlier from DL, IML 768. It was one of about 3 that haven't really done anything in the way of growth since day one. But it is the only one that seems to be going backwards. No new growth but the leaves are yellowing.

It's supposed to be one of the single monsoon climate Hoyas, like the rest I bought at the time. The automatic irrigation is set to come on once every 3 days which I didn't think would be too much water.

On the weekend I pulled the plant out and although it's got a dense ball of roots coming from the stem, they don't look altogether healthy. No new looking roots and some of the old ones look like the ends have rotted.

I half filled the pot with gravel, put a little of the old soil in, more gravel, and then replanted. Not knowing any specific requirements of the plant makes it a bit difficult to know what to do next. But the roots did make me think they had it too wet. Hopefully the gravel will cure that.

Anyone have any ideas on what might be best to do at this stage?

Photo of the plant after putting the gravel into the pot.

I let mine get dry between waterings, but mine is a houseplant, and completely different from your conditions with them being outside.

I would think that if its from, as you say, a "single monsoon climate" that it would prefer to be grown on the dry side. But again, perhaps 3 days is enough to let it dry out between waterings where you have it growing.

I wish I could be more help.


Christine

Ive had young plant's roots rot back when they are young. Some dont seem to like being put straight in a larger pot at first and to be kept drier, others dont mind what theyre in.
If it were me, and Ive done this before, I would knock it out of its present potting medium, cut off the bad roots, and replace it in a smaller pot with a much airier medium , and keep it well misted, or into a propagator to re build its roots.
And if that 3rd leaf which is still green looks healthy, Id cut the plant into 2 pieces , leaving as much stem as you can below the green leaf, so you end up with 2 cuttings to try and root.
To check the roots, if you give them a gentle tug and they come away leaving a thin fibre which had been running down the centre of the root, then the root is a gonner and it should be removed....in my opinion


Dominic

This message was edited Nov 8, 2009 3:40 PM

I would echo what Dom says.... Every 3 days watering seems like alot...but then you are very dry there in the winter. My big mindorensis gets igored and watered maybe every coupld of weeks. I didn't know it was single monsoon type...and the other one in the gh I jsut let it dry with the others before I water. I water about once a week, thoroughly, and hose everyone down "mist them" briefly everyday to cool the leaves.

Originally when going through the catalogue I selected warm growers. DL suggested some changes, stressing I should go for single monsoon species to better suit my climate. From that I assumed all the ones I got from him were single monsoon climate.

Looking at the mindorensis it's "telling me" there's too much moisture. None of the others are showing the same effects. Sussuela (both McIlwraith Range and Bamaga) are rocketing along now. Walliniana is running all over the place. Macgillivrayi is putting on a burst. The only one not going anywhere seems to be clemensiorum which is static, and then there's mindorensis which is going backwards.

When I get home again we'll see what putting all that extra gravel into the potting mix has done. Having the plants in a large treed area helps keep humidity up, but there's definite limits to what you can do when you operate in the Great Outdoors.

High temperatures automatically draw down relative humidity. At night our RH is normally between 85% - 95% even in the dry season. With a constant water content, when temperatures then go up to 38C - 40C the RH plummets. The change is the capacity of the air to absorb more water rather than loss of water, ie relative humidity.

H. mindorensis has always been easy for me to grow...I guess. In the GH they get watered along with all the others (not treated as single monsoon)...and outdoors it has been in the same pot now for 6 years...I water when I remember, it does get a bit of rain sometimes and it blooms like crazy!!! I should remember to water more. It is in a 14" bulb pot (I find hoyas lovet he bulb pots)....