Ornery non-bloomers

rennflApril 14, 2012

Hi all,

Need some advice here. I've got a couple Hoyas that are definitely big enough to bloom, but won't.

Any advice will be greatly appreciated.

First, sp. Tanna Island (or whatever it's called now) I've posted asking advice for this before, still won't bloom. One thing I though of, could this be one of the ones that need to cascade down to bloom? Just a thought.

Second, Hoya dasyantha. Grows like a weed, and I'm giving it conditions that carnosa blooms in. Maybe it doesn't like that, although it grows well with those conditions. Any tricks?

Hoya diversifolia. As least that is what it came to me labeled as. Grows well, won't even put out a penduncle. Advice?



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puglvr1(9b central FL)

I only grow h. diversifolia out of those you mention (although I have my fair share of non bloomers as well). I have found diversifolia to be a very shy bloomer at least mine has been. Its HUGE and yet it took what seemed a long time before it bloomed for me and when it did...the blooms were SO small it wasn't worth all that waiting,lol (IMHO)...other than giving it more light and fertilizing regularly I'm sure you're already doing all those things...now its just the waiting game. Good luck getting of those to bloom for you, I'm sure they will sooner than later.

    Bookmark   April 14, 2012 at 4:28PM
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I think that the most important factors in getting a mature Hoya to bloom are proper light and nutrition. The really fast growers need more fertilizer than the slow growers. Species like Tanna Island need to be fertilized with a half stregnth fertilizer solution at almost every watering when they are growing. Also try using a bloom booster type fertilizer every so often to see if that helps. You can also use 1Tbsp of Epsom Salts per gallon of water, use a few times a year to either help green a stressed plant back up or to give a nudge to encourage blooming.

Species with thick leaves like Hoya diversifolia like a dryer period during winter where you let them dry out and then water again. When spring rolls around or when strong new growth begins then start watering heavily again and start appliying fertilizer frequently again as well. If you do not have your plants well lit during the winter that will slow them down as well.
Hoya dasyantha should bloom best when the nights are cool. Aim for medium green leaves, dark green looks nice but often results in no blooms.

Another tip that I can't stress enough is to not trim the bare vines. Many Hoyas send out long vines that never seem to develop leaves but some use these to boom from and many will later fill in with leaves as well.

I have some really big plants that have never bloomed but I am convinced that they were not getting enough fertilizer for the last couple of years. Also some species want quite a bit of water during the summer and resent drying out so this can affect blooming as well.


    Bookmark   April 14, 2012 at 11:51PM
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Thanks for the responses.

My hoyas get fertilized at the same time and strength my orchids do, and as I grow the orchids in inorganic media, it is pretty regularly.

As for light levels, both of them in winter receive direct sun from sunrise until 11am or noonish. Now, as it is hotter, and the leaves were getting a little too yellowish, they are in the spot beside the Brassavolas, and at this light level, the Brassavolas bloom. So that is a good amount of light. I could inclease light some more, to about Vanda level, but that seems a bit extreme. Or not?

Sorry for using orchid terms to describe light levels, but Mike I know you grow them, so this should make sense to you right?

I'll try a couple doses of Epsom salts. Growing orchids, I've got that around always.

As for watering, in the winter, they were outside, so they both were allowed to dry out pretty well in between waterings. Now, as it is warmer, they are getting watered more often, but again both approach/reach dryness before being watered. I could increase the watering on the dasyantha, but I'm afraid to rot out the roots.

And actually the dasyantha is due to be repotted today, as long as I can get to it. If not it will be done in about a week. It is currently in orchids seedling mix, but as I look in the pot, it looks like it is just a mass of roots. Going to move it up another inch pot size.

And don't worry, I never trim bare vines. They do eventually fill in.

The diversifolia, is one of the first Hoyas I ever got, in early 2008, so it's a monster now. Treated the same way as the dasyantha, in fact it is sitting right beside it. It needs repotted too, but that is going to be a serious job, so me, being me, will put it off until it becomes an emergency lol


    Bookmark   April 15, 2012 at 8:30AM
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penfold2(4b, MN)

Be careful with epsom salt. The frequently suggested dose of 1 Tbs per gallon is a massive amount that will add about 150ppm Mg and increase TDS by about 1500ppm. Not only is that a very large increase in TDS, but it will throw off your Ca:Mg ratio as well. If you suspect you have a Mg deficiency, I'd try a much more moderate dose of 1/4 teaspoon per gallon, or try some Cal-Mag fertilizer which supplies both Ca and Mg in a proper ratio.


    Bookmark   April 15, 2012 at 11:46AM
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Hi Renee,

Patience is really the key to growing Hoyas. You said you've only been growing them since '08 - that's really not that long! I have species I've grown for years and years and years that have yet to bloom. A good example is australis ssp. australis - I can't even tell you how many years I've had it... let's say at least 15 years. It's huge - it finally put out one flower cluster last year. And it has several peduncles now that seem on terminal hold. They have that "fuzzing up" look, but have been in that position for some time. Yet australis ssp. tenuipes bloomed for me within 2 years and is a HEAVY bloomer.

I think because we're growing them in our homes, far away from their natural habitat, with different lighting, in pots, using chemically treated water (though I use RO water which should help), using chemicals to get them to grow/bloom/stay bug-free... All these factors have a hand in slowing down the normal blooming cycle. The fact that they grow so well and DO eventually bloom is a testimonial to how resiliant they are. If your Hoyas are growing well for you, it's probably just a matter of time with most species. That's why I grow species whose foliage I love to look at - I figure if they never bloom, they'll still make my eyes feel good.

Of the three you mention, I grow dasyantha and diversifolia, neither of which have bloomed for me either. Dasyantha is a lovely plant that will stay in my collection because I love the leaves. Diversifolia, on the other hand, doesn't do much for me. It's a little too "messy" looking for me. If it doesn't bloom soon, I'll probably trade it off for something else that grows a little "tidier."

Denise in Omaha

    Bookmark   April 15, 2012 at 2:01PM
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Chris I admit that when I use Epsom salts that I don't mix up a gallon at a time so I was just going off of what I was told many years ago by some orchid growers, the 1 Tbsp per gallon. I always mix my solutions up in a large watering can and that is probably about 5 gallons with 1-2 Tbsp of Epsom salts.
I wanted to see just how hight the TDS would jump with the ratios I mentioned initially and I was quite surprised by the results. I measured my tap water at 135 TDS and then added the 1 Tbsp Epsom salts to the gallon of water. The Epsom salts solution measured 235 TDS which was surprisingly low. Obviously this is only the TDS (total dissolved solids) or electro-conductivity of the solution but this is an important way to determine just how strong a fertilizer solution is. Usually I aim for fertilizer solutions to be below 250 TDS so using this Epsom salts solution would not concern me too much., still I have always liked to use Epsom salts for plants that are heavy feeders or heavy bloomers and skip it for the bulk of my plants. The Cal-Mag fertilizer is something that I might look into, seems like a good alternative. I admit that I am terrible at math but there must be table out there where one can look up specific info on fertilizer solutions, I'll have to do some reading I guess.

One thing that can cause issues is if you are from an area with hard water, well water etc. Adding anything to water that is already heavy in dissolved mineral salts can quickly go above the limits that plants can tolerate. Ideally we would all be using rain water or reverse osmosis water but that just does not happen. I think that everyone who is serious about growing plants could benefit from owning a TDS meter just so they can control the strength of fertilizer solutions.

Denise I had ordered an unidentified species last year that was collected on Timor Island in Indonesia. It turns out that the plant is a small leafed version of Hoya diversifolia or some other close relative. I had never wanted this Hoya because it just does not excite me either but now I have one. I hope in time it grows on me (not literally LOL) but I think I may end up with similar feeling to you when it comes to this Hoya.


    Bookmark   April 16, 2012 at 11:43AM
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Diversifolia gets a lot of hate lol. Honestly, it makes the ambivalence kerrii is subjected to look like a love affair. That kind of makes me determined to love it. Somehow, it seems more important to get plants like these into the conditions they crave. Because they can't afford to just sit back and be swanned over for occasionally producing a new leaf, like latifolia or macrophylla. They have to do something impressive or they will be bounced around from home to home like foster kids.

The temptation is to stick it in a corner and let it survive like a corporate rubber plant, but let's instead cast it as the scrappy underdog of an 80s movie. Mine got great light and winter dryness, so I'm going to start playing with my fertilizer schedule.

    Bookmark   April 16, 2012 at 12:17PM
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penfold2(4b, MN)


Your TDS reading seems incredibly low for how much epsom salt you're adding. Some meters use a "x10" icon when displaying large values, so 235ppm could be 2350ppm. Are you sure this isn't the case?

My calculations are as follows (sorry if I bore anyone):

1 TBS epsom salt = 12 grams
1 gallon water = 3785 grams


Take into account the fact that epsom salt (MgSO4.7H2O) is 51% water, which does not contribute to TDS, and you're left with 1548ppm.

I've tested a 1 TBS per gallon solution and got an increase of about 1100ppm. I assume the discrepancy is due at least partly to the fact that TDS meters measure conductivity and then use a conversion factor to estimate TDS. My meter uses a conversion factor for KCl, so the TDS reading may not be entirely accurate when measuring MgSO4.

I agree that TDS meters can be very useful, but I would be concerned about the accuracy of your meter if you're only getting a 100ppm increase from a 1 TBS per gallon solution of epsom salt. Or maybe I misread something in your post.

Sorry for the tangent everyone.


    Bookmark   April 16, 2012 at 7:48PM
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Yeah I was skeptical but my meter seems to be ok, it ready properly when I check my RO water etc. I have not calibrated in a long time so I should probably do so. I have an inexpensive Milwaukee TDS meter so I could always just get a new one if calibration is off.

I do think that it's important for us to talk about these things. No one wants to accidentally fry their plants because of a fertilizer error. I know I have had some disasters though the years and they were almost always due to experimenting with something new.


    Bookmark   April 17, 2012 at 12:22AM
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pirate_girl(Zone7 NYC)

Hi Folks,

Am at work, so just a quick word. I'd agree w/ caution abt the Epsom Salts. Those of you who remember Cena (grows Hoyas & Orchids among others), may remember she spoke of having used the ES since her DH had them around a lot for a foot soak. Don't recall how much she used, but she recounted that she'd damaged some Sans. she had due to too much of this, so beware, so I'd err on the lighter side.

    Bookmark   April 20, 2012 at 2:08PM
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