Hi, Patti - I Use the 5:1:1 mix, so that or some rough equivalent would be a better choice than gritty mix, which would be overkill for plants that need annual repotting. I always let the plants start to go dry just before I expect first frosts to knock back foliage. After the freeze, I lift the tubers from the soil and remove most of it (soil) by hand, then set the bulbs on a table covered with newspaper or cardboard to dry. After leaves are dry, I cut them back, remove the rest of the soil from the tubers and put them in a paper gag with dry peat + some flowers of sulfur (powdered sulfur - used as a fungicide). You need enough peat to keep the tubers separated from each other and anything that doesn't breathe - like a plastic pot wall or a painted surface.

In spring, I plant them in moist soil on our last frost day. If that might seem late, but it's not. The tubers won't do much until the container soil temp is reliably above 70*. If you put them out while night temps are well below 70*, it increases the potential for rot, so if it's not too much work, be sure to bring them indoors for the night until it warms up considerably.

You'll have better results in the subsequent growth cycle if you give the plants a winter's rest. They're fertilizer hogs, so make sure you keep them satiated.

Al

Al, You are saying that it is better for me to let them rest for the winter here in Chicago and then bring them back out in the Spring, yikes. I will try that method but I am better at keeping things alive then I will be at this resting period. Ha!! Thank you for the quick response. I am a bit confused about the mix then. I want to use your "soils" next year for my annuals and I want to use it for my houseplants as well. What I thought I read was that the 5:1:1 mix is good for annuals outside and the gritty is good for houseplants. I have bookmarked a lot of your responses and will read them again but I wanted to replant my houseplants before winter so they will be all set for the next 6 months in your mix. Is it not a good time to do this and should I wait til the spring to replant? I had it this year with the miracle grow mixes and I came to find this wonderful forum and all this great information. You have helped so many by what I read and now you are helping me. Thank you in advance for all the help.

"What I thought I read was that the 5:1:1 mix is good for annuals outside and the gritty is good for houseplants." That's a generality - true in most but not all cases. Whenever I grow plants I know will need repotting every year, I almost always opt to grow them in 5:1:1. It's less expensive AND less work. Datura, brugmansia, caladium, colocasia, hybiscus, are a few of the plants I always pair with 5:1:1 because I can be absolutely certain that all will be very much in need of a repot after 6 months to a year of growth, depending on the locale.

Most houseplants should not be repotted in early spring. In fact, that's the worst case scenario in most cases because plants are at their weakest (in terms of growth rate and energy reserves). Very late spring and very early summer is best for at least 90% of the plant material we grow as houseplants, which is why I so often mention Father's Day or the summer solstice/first day of summer as time markers that are easy to remember.

Thanks for the kind words, Patti.

Al

I too want to have Caladiums as house plants this winter. So far I didn't get an answer on how long Caladium bulbs must be dormant. I'm going to try 1 week and pot my dormant bulb in a couple of days. Then I'll keep my fingers crossed.

See my 9/7 at 9:17PM post that has a Freida Hemple Caladium photo & its bulbs:

http://forums.gardenweb.com/discussions/4820601/question-and-reassurance-please

...and this one from last night on drying / curing bulbs:

http://forums.gardenweb.com/discussions/4856789/store-bought-taro-doing-great-when-do-i-harvest

2 of my Caladiums went dormant over the last couple of weeks and the rest slowed their growing. And, of those, some are getting dull in color and are not replacing leaves as fast as they die off. We've had 3 nights in the past week that were 46 deg F.

The cheapest indoor potting soil is what I've been using. After reading up on Fungus Gnats and fungus on potted plant roots/soil I've decided to use the 5:1:1 soil formula for future indoor plants.

Al, I have a question about the Father's Day/Summer Solstice rule of thumb, if you don't mind. I'm in San Antonio, zone 9a, 29.5*N. Today's length of day is 12:25 hrs (13:13 hrs of visible light) and it's forecast to be 95F (w lows in the low 70s) for the rest of the week. It seems to me like all my indoor plants are still going strong and highs don't stay below 70 here until early December, so I'm wondering what kind of flexibility there might be in the repotting timeline for southern latitudes. Is the major factor hours of daylight, average temperatures, or something else? Thanks!

The closer to the equator you are, the less notable benefit there would be in adhering to a repotting time table based on the growth cycle. The primary factors that make repotting in June a superior choice in northerly climes center on light intensity and day length. Technically, it's the length of night or dark period, but really no need to draw distinction for this thread. Temperatures do play a role as well.

Also, many plants do very specific things and react to increases/decreases in day length by changing their growth habit or even growth phase. For example, many of the trees I grow as bonsai slow down multiplicative growth and increase additive growth, i.e., they stop extending/making more leaves and branches, and start storing more and more of their current photosynthate (sugar/food) in files of cells in cambial tissues, which creates thickening (additive growth) instead of the multiplicative growth mentioned. Here in MI, all my Ficus turn off very quickly in late Aug - they just (nearly) stop extending, even though temps are still warm and it's been quite sunny as of late. I attribute that to a day length response. It's funny, the Ficus won't grow much, even under lights, until the vernal equinox. At that point, they'll start pushing in earnest. The strange thing about that is, they over-winter in a basement, under lights on 16 off 8. There is 1 - 16x32" window in the basement that is completely blocked by a rack of clothing. It's VERY dark in the basement at midday with the lights off, yet this tiny bit of light that makes its way in is enough to tell the plant when it's time to do all the things they do as a photoperiod related function.

Al

Thank you for the detailed reply. This makes a lot of sense...and also makes me really curious about the growth habits of the same species in comparable environments at different latitudes. (I just googled & came up with days upon days of reading. Yay science!)

caladiums will go dormant for sev months no matter what you do. Even in south FL now rezoned as z11 they loose leaves for winter and then resprout.

I bring mine in from outside to let them decline slower so they'll have may be extra 4 weeks in Oct, but then they need to be kept dry until mar-apr.

I grow one very large one 'Red Flash' completely indoors, since my balcony is very windy and it produces huge leaves. i've had it for more then 10 years :).

perhaps you can wake them up earlier in feb by putting them on a heat mat - you should keep the mix moist at all times . but that's a lot to bother with...

but i must add that they DO plant them in planters for winter display in Z11 in Miami and they do grow, but not very well (they resprout corms for that naturally :)). The planters stay warmer then the ground and they put them in dappled sunlight, not in total shade. So they really warm up during the day - i think that's a factor to sustain growth.

the winters have been exceptionally warm with 80-92F in dec and feb and 70-75F in jan. and the light levels are super bright even in winter. Nothing like that indoors.

They do like to be very warm above 80F and 70s at night. nights below 65F stall growth.

it would be interesting to experiment to see how soon they will wake up if put on a heating mat. or if they will continue to grow on a heating mat indoors and for how long.

and one more:

i usually start them on a heating mat in spring - when i tried doing it at an earlier mar 1 date - they just sat for 1 mo and produced hardly any roots (and no leaves).

so now i start them later - when put on a heat by late april, they leaf out in a few weeks. and light is much stronger then too and they begin to really bake in my west window and love it :).

and one more: ;)

it's been my experience they really sulk if you bare-root them for xfer to a diff medium even in summer and that stalls growth in a big way or they even decline alltogether - so i would not recommend that at all. only uppotting.

yours have probably been exposed to cooler temps at night too. once they go to below 60s at night they will be prone to tuber rot (dry or wet). I overwinter mine, so when i let them grow outside till the end of oct - i say goodbye to tubers. no survival, unless you unpot , clean and dry them up. but then the small tubers dry up too much and won't make it ...

so, only makes sense to play with very large tubers, or min 1" in diameter.

Petrushka - Thanks for the help. I did not realize that the best for them was a long winters "nap" so to speak. I will take Al's advise and after the first frost I will do what he directed me to do. I thought they can be grown all year and I even bought a great pot to put them in. I will just have to get a few different house plants for that new pot. lol. I really like all of them and all the colors are so great. If they don't survive I will just try them again in the spring. Chicago has long cold winters sp I do enjoy my house plants while I cant garden. Thanks again all!

you shouldn't wait until the first frost - small tubers will rot by then in damp and cold soil. so it depends on how large your corms are, which varieties you have and how damp your soil gets in the fall, etc. they should be kept very dry after it goes below 60F daytime.

it's a tropical after all - you can dig them up soon as the leaves die out, which should be much sooner then 1st frost.

leaving them below 50F at nite is a sure recipe for rot - you'll have to dig/dry/dust them then for sure. i don't do that, since i don't let them sit outside so late.

i overwinter mine in their pots dry, without digging, until spring.

Yup. In tropic, caladium is fast growing, but it's leaves also relatively fast dying no matter how the temperature is. Keep save the tuber for regrow next season is the best.

Patti - allowing the plant to start drying down just before the first frost knocks it back provides a double message to the plant to stop growing and enter into a period of 'consequential dormancy', which is different than the 'predictive dormancy' most are more familiar with; and, almost all university sites suggest that you lift and store the tubers as I suggested. If they don't suggest that you store them in dry peat, or treat with a fungicide (like flowers of sulfur), they should. Leaving them to over-winter in the soil they're growing in increases the likelihood of rot because it encourages the plant to keep growing, which produces herbaceous tissues susceptible to rot so I wouldn't recommend that you go that route.

Overwinter the tubers ......

Al

They are really still so pretty right now so I hate to take them out right now. They are all so full. I will stop watering them so they can start to dry and I will put the pot where they will get no rain so I know that they are truly dry and ready to be lifted and stored properly. Unfortunately I have them in Miracle Grow potting mix that never dries out completely. Next year I will make my own mix for all my containers. Thanks all. :-)

it's still warm in chicago - i see 80s and mid 70s mostly for the next 2 weeks - so they'll still need to be watered. but around sep 26 will dip at nite to 53-55F and daytime low 60s. so by that time they should be drier. However, when bone dry - they will just wilt and go caput. and not recover. so keep checking the soil with a chopstick or skewer.

very often in the pot the bottom is moist while on the top couple of inches is totally dry. about half way down dry should be ok when in mid 60s. don't soak them to dripping- just dribble some water. in the tropics the dry season approach is 'sporadic light rain', not soakers and cooler temps. then they'll decline slowly.

so they'll be ok until then. as a rule if you see most leaves declining and new leaves not coming - it's a good time to lift them up.

by the way most sites say that normally they stay dormant 8-10 weeks. growers lift them for min 6wks from what i could find.

and they say tubers decline if it goes below 55F. and of course in the south when the frost come it could still be quite warm during the day warming the pots/soil.

but not so in chicago. the days would prolly be in the 40s and 50s - way too low.

Best luck, Patti.

Al

Thank you Al and Petrishka. I only water them when they need it because like I said they are in a bad potting mix that does not drain well. I have learned Miracle Grow potting mix just doesn't not drain well when my geraniums all rotted due to the rain and the potting mix. I have the Caladiums on my front porch in the shade and a bit of shelter so they don't get much rain.I can't say what this forum has done for me this year. My tomatoes and cucumber are still producing because of help from others on the Growing Tomatoes and Veggies forum. I have learned from so many knowledgeable folks helping us newbie gardeners.

P - you might not yet know how to appropriately use ballast in the bottom of your pots to significantly reduce the negative effects too much water in your media has on your plants. If you don't know, and want to, let me know. It can make a very big difference in how much of their genetic potential your plants can realize when in heavy (water-retentive) media.

Al

Al, I would love your help and feedback. I plant to make my own medium next year for all my pots using your "recipes" and I'll have all winter to read all the information that I printed and get prepared. I will repot my house plants in spring/summer when doing my annuals next year. I was really disappointed this year with the Miracle Grow potting mix and in the big city here we just don't have many choices at the big box stores near my home. I don't like throwing money away on flowers and this year I lost many flowers to root rot due to poor draining mixes. All my planters have good drain holes so I know that is not an issue. I am looking forward to my flowers next year and may even try to start some from seed in the house. Thanks again for taking your time to help me!

Me too. Please do share the info on the ballast. I'll have several potted plants indoors this winter. More than in past winters.

You may not realize it, but enthusiasm is an attractant. Folks are always more willing to help those that exhibit an upbeat, enthusiastic attitude, and a willingness to do part of the work. It's much more rewarding to help someone like that, than someone who arrives with the sense that they deserve to be spoon-fed information, then in the end, wind up choosing what's easiest over what makes the most sense.

I've talked enough about using ballast in the last couple of weeks to think a thread about the topic might be useful/helpful; and, I haven't posted a new thread in quite a long while. I worked on it for a couple of hours earlier this evening, and I'll likely finish it in the morning and get it posted. When I do, I'll either come back and link you to it, or just paste it into a text box here on your thread. I think you'll find it interesting.

Take care.

Al

I'm bookmarking this because I want to save the link for the next time I want to re-learn about it!

My hope is that many of you will bookmark this post and provide a
link whenever you come across posts written by others in search of a
remedy for problems caused by a saturated medium. As a member of Garden
Web/ Houzz who has been assisting members with their container gardening
adventures since 2004, I’ve discovered that an extremely high % of the
problems growers bump up against are related to excess water retention
in the media (soils) they use. The cause of some of these issues, like
poor growth and spoiled foliage, are often very apparent. In other
cases, where insect infestation and diseases are at issue, the cause
might not be isolated as facilely; still, root systems in poor health
and with limited ability to function efficiently due to excess water
retention in the medium, affect the plant’s metabolism, which in turn
affects the effectiveness of the plant’s natural defenses against
diseases and insect herbivory. So, where we might be inclined to levy
blame for low vitality levels in plants affected by the insects/
diseases we can readily see, in most cases the opposite is true. Low
vitality/ weakened plants that result from poor root health, caused by
excess water and an insufficient volume of oxygen in the root zone, is
the reason underlying most cases of root/foliage diseases and insect
predation.

Without question, the best way to resolve problems related to excess
water retention is by using a soil that allows you to water correctly.
This means using a soil that allows you to water to beyond the point of
saturation, so water is draining freely from the drain hole(s) w/o the
plant being necessarily punished by a subsequent period of soil saturation
that limits root function and damages root health. Understanding what
drives water retention in container soils probably represents the
largest step forward a container gardener can take at any one point in
time. Read more about it here.

Perched water is water that is so tightly held by the force of
capillarity it won’t leave the pot, even though the force of gravity is
exerting its downward pull. Capillarity is the sum of the forces of
cohesion and adhesion and what causes sponges to be moist, even after we
thoroughly wring them out. Cohesion causes water molecules to stick to
other water molecules, which is why water forms drops. Adhesion causes
water to stick to dissimilar molecules, like those in soil particles and
pot walls, and is the reason that drops of water can be observed
adhering to even perfectly vertical surfaces. Acting together, the
cohesive and adhesive forces in container media are regularly
observed to be stronger than gravity, thus preventing water from moving
downward and out of media through the drain hole(s) that should be a
part of every conventional container planting. When capillary attraction
is stronger than gravity, water ‘perches in the soil above the
container’s bottom. Since it is primarily the saturated fraction of the
medium that acts to limit root health/ function, anything we can do to
reduce the amount of saturated soil in a container, the less potential
soil saturation has to limit root health/ function.

Finally, to the point of this post, which focuses on how to use
ballast to limit the volume of soil in any container that is capable of
holding perched water. First, though, it is important to note that the
amount of perched water a soil can hold varies from one soil to another
and by container size shape; BUT, the height of the perched water table
supported
by any given soil will be the same in any container size/shape used.
That MG Moisture Control Soil you might use, the one that supports 6” of
saturation at the bottom of the pot? No matter what the size or shape
of the container, when the soil is saturated, it will always support 6”
of saturation, i.e. until that ht. is reduced by way of evaporation or
evapotranspiration.

If we use a “drainage layer” of stones/ gravel/ packing peanuts …, it
doesn’t increase drainage. E.g., if we have a pot that is 12” deep and a
soil that supports 6” of perched water at the bottom of the pot, adding
a “drainage layer” simply causes water to perch to a ht of 6” above the
drainage layer. Whereas the max height of the drainage layer would be
6” from the container’s bottom w/o a drainage layer, adding a 3”
“drainage layer”would cause water to perch above that to a ht of 9”, which is actually an effort that ends up being self-defeating.

Let’s use our mind’s eye for a moment to visualize what using ballast
can do for us in terms of reducing retention of unwanted or excess
water. We already learned that the potential ht of a perched water table
remains constant for any given soil. For this visualization, we will
use a soil that supports 4” of perched water/ soggy soil. Let’s also
imagine that our container is 9x9x10” deep. The potential volume of soil
saturated with perched water is equal to 9x9x4, or 324 cubic inches.
But what happens if you place a 4x4x8” brick in the bottom of the pot as
ballast before you fill it? The brick takes up 128 cubic inches of
space that would otherwise be occupied by saturated soil. Let’s add 2
bricks, so the amount of soil that can hold perched water is reduced
from the 324 cubic inches w/o the 2 bricks as ballast, to only 68 cubic
inches, with ballast - less than 1/5 the amount before adding ballast.
With a little planning, you can reduce the volume to less than 10% of
the amount of soil saturated before adding ballast, which goes a very
long way toward providing a remedy for woes related to saturated soils.

One very important consideration relates to the fact that there must
be a continual soil column that extends from the top of the soil to the
bottom of the pot. If you had an 8x8x12” pot and were using a soil that
supports 4” of perched water, adding 2 – 4x4x8 bricks would fill the
bottom of the pot, which would cause water to perch 4” above the bricks;
but, if there was a small crack between the bricks that allowed an
unbroken soil column from the soil mass above the bricks to the bottom
of the pot, the only perched water in the entire configuration would
reside in the soil occupying the small space between the bricks.

In addition to using ballast, there are other tricks that employ some
simple science that allow you to reduce the amount of water a given
soil can hold. You can read more about them here. You can read more about them here.

The first link I left,
at the end of the second paragraph above, explains a concept that makes
growing proficiently much easier on multiple fronts. I highly recommend
you take the time to become familiar with it to the degree that by
default, it's part of the compendium of container gardening knowledge
you can apply at will. When you understand and put the concept it
explains to work, using ballast won't be necessary.

If you think it might be helpful, I can provide a few sketches I drew that should help to clarify some of the info provided.

Take care.

Al

I found your drawings really helped me understand the concept as I read through your previous posts. Should I post them on the new thread?

I posted them, LB - thank you. I apologize for the formatting above. I have no idea why the original document I produced doesn't work in Houzz's text box.

Al

Sorry, they're not showing for me. Might be a personal problem with my magnetic field or something...