Why do my Rexes always die?

Christiana, TN(Zone 7a)

I live in TN. I can grow canes just fine. Have a great soil mix.
But my Rexes and most rhizomatous just fade into oblivion.
Could it be hot temps? Or what?
Please help.

Lake Stevens, WA(Zone 8a)

Hmmm, are we talking about Begonias?

Powder Springs, GA(Zone 7b)

Quote from quercusnut :
I live in TN. I can grow canes just fine. Have a great soil mix.
But my Rexes and most rhizomatous just fade into oblivion.
Could it be hot temps? Or what?
Please help.


Rexes can be fussy but once you learn their traits and how to care for them, they are as easy as a cane begonia. Since a rex is a rhizomatous then you can treat them similar with the exception that rexes may go semi-dormant in winter so cut back on water when they defoliate.

I guess we need more information about your growing conditions and watering habits first. I find most rexes and rhizomatous are planted in too much peat and deep pots. I would change any heavy peat mix out for a faster draining mix to ward off rot from too much wetness. I prefer bowl pots (pans) to standard pots but they are a bit more difficult to find. Are you growing indoors or out in warmer months? What kind of light do you provide in winter? It took me a lot of years learn what is best for my rhizomatous and rex begonias and wish there was a very informative site on what to do other than grow in a perfect greenhouse with careful watering. This should not be rocket science in other words. I still lose begonias every year - summer and winter (most in winter from not enough light or too much water) but the successes have become much more than the few failures.


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Christiana, TN(Zone 7a)

Hi, hc. Thanks for responding.
It might be too much peat. I have to run but I am going to come back and give more info.
Thanks again. Be back soon as I can.

Christiana, TN(Zone 7a)

I have been using standard pots. I have some new azalea pots I'm going to try.
I usually lift the pot to see if it's light enough to need water. I grow outdoors in shade in warm weather then fluorescents in winter. My potting mix is peat based with perlite and pine bark. Also lime, gypsum, trace minerals and starter fertilizer. Wetting agent also. I get it from a local nursery supplier.
The canes and most other plants do well in it. When I fertilize I use Alaska fish emulsion.
Any ideas?
My latest and only two rexes are Jurassic Silver Point (left) and Jurassic Silver Swirl.
I added about one-third finely chopped dry oak leaves to the mix on these.

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Powder Springs, GA(Zone 7b)

Sounds like you are doing things right. The pot on the right may be a bit large for the plant in it though - start with a pot sized for the plant and move up as it grows.

Almost all these begonias are in 3 inch pots and need to be moved up for example.

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Christiana, TN(Zone 7a)

hc, they both were the same size when I planted them. The small one is a good example of my problem. Both treated the same and one is already in decline.
Would you suggest trimming some roots and repotting?
Do you make, purchase, customize your potting soil?
Btw, I forgot to say your rexes are spectacular.
*envy* 😣

Powder Springs, GA(Zone 7b)

I just use Miracle Gro potting mix - the KISS method. I have stepped up fertilizer this summer - hose end sprayer with water soluble fertilizer at 1 TBSP per gallon. Not sure if it makes that big a difference but as long as they don't die on me, I'm good.

I just took a second look at your photo and the second one's surface looks a bit dry. Other than that they both look healthy enough.

We still have several weeks of good growing weather left to eke out as much growth as it can muster. A lot of mine get some direct sun - maybe a couple of hours and filtered light for many hours.

Here are a few more from August 30

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Powder Springs, GA(Zone 7b)

And from yesterday

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Christiana, TN(Zone 7a)

Many times I can't tell by looking at the surface. I have pots where the surface looks wet and it will be dry as a bone. And vice versa. When I'm in doubt I have to check the heft of the pot by picking it up.

Powder Springs, GA(Zone 7b)

I hear you on sensing the weight of the pot for signs of dryness/wetness. I sure can't do that with mine - way too many! The old timers/experts/pundits say to stick your finger an inch into the soil and if it feels dry, then water it thoroughly. Again that would take forever for me and I'd have one wrinkled up dirty finger if I did that to all my pots.

What I look for is how wet it looks on the surface and for signs of wilt. If the soil looks wet I may skip watering it that day but if dry looking then I water it. If the plant is wilted and the soil is wet then it may be roots are rotting or maybe the surface is wet but the root ball is dry - the finger test is good in this situation. If the soil is really dried out and the plant is wilted then usually a thorough watering will revive it. In summer I try to check daily and often water by overhead showering. Sometimes a thorough watering is needed though and you will eventually see what plants are extra thirsty and which ones aren't. In winter I have to be a bit more judicious on what to water and how much.

Anyway hang in there, you have to kill a bunch to get the hang of it at times.

Here is an old adage from the Aussies (this was added to the ABS "The Begonian" magazine a few years ago)


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Lake Stevens, WA(Zone 8a)

Hah!
I am still a novice, having killed quite a few.

Powder Springs, GA(Zone 7b)

I must be an expert since I think I have tried new methods to kill them disguised as a way to make them grow faster. HA!

Two things that will kill them quick - doting on them too much (usually too much water) and pure negligence which takes longer to kill them (where you don't water them or check on them for days or weeks on end).

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