root pruning

[topshelf12]

  When is the best time of year to do root pruning?  I have my plants in 10 or 11 inch pots.  I think I read to take a couple inches off the roots  from the bottom of the root ball. I would think a sharp sterilized knife would be best. Also, I have some Fox Farms Microbe brew that I gave them about four months ago.  Should I give them some more right after I root prune them?
Thanks
Norm
Clear sunny and 44 degrees

[helixturnhelix]

Outdoors I would do it late spring, when your plants are starting to come out of the winter doldrums.  This way you could also remove the roots that have died due to the cold winter weather.  I would also prune the top at the same time as the roots because it will allow your plants to deal with less evapotranspiration stress if you also reduced the dumber of leaves that need water in addition to roots.

Indoors: anytime of year is fine, I would also prune the top in this case as well.    

[Charlie]

There was a retired couple in Houston who had hundreds or possibly a thousand potted plants in their yard. Every other year they would root prune most of them - huge job but they found it renewed the plants better than anything else. My greenhouse experience has been similar - in pots roots stop growing eventually and by pruning up to 1/3 of them away and adding in fresh, high quality potting mix you can get a very nice response from the whole plant. Remember, growth hormones for the top of the plant are manufactured in the roots and new, growing roots are the best producers of these hormones.

I agree with the advice on timing that Chris provided, with one additional comment. If the hibiscus are indoors the temperatures and light need to be conducive to growth. Too cold or too dark and it would be safest to wait until spring.

Charlie

[roadrunner]

Charlie do you only prune the roots on the bottom of the root ball or in some cases should roots on the sides be prunned back a bit as well?

dave

[topshelf12]

thanks Chris, Dave and Charlie.  I have hibs in the greenhouse and about 10 inside. The ones inside are in low light east window and are kept 58-68 degrees. I think i will wait until spring.
thanks as always for the great info and quick response. This is an awesome forum!
Norm

[Charlie]

Dave, I think taking a little off the sides is good with most coming off the bottom. It's also a good idea to see if you can scrape up to an inch off the top, too. This layer can contain hiding and burrowing insects and removing it takes some pest load off the plant.

Charlie

[roadrunner]

Thanks Charlie.  I've done that with other container plants like lantana, roses, and buddlea, but not hibiscus.  Lantana and buddlea get really bad mats of roots on the surface that need to be essentially raked every year with a hand cultivator to break them up and then trimmed.

Here's a problem I have that's related to being very negligent on root prunning.  Last spring two of my fastest and most vigorous growers never really got going when the weather warmed. They were in 10" pots and had gotten to 5 feet tall the previous year. They were gorgeous. When I pulled them out of their containers to see what was going on, I was shocked to see several large very long roots had spiraled several times in the bottom of the pots.  I guess I didn't expect this since 2 less vigorous cultivars of mine (Tamibon and Aztec Sun) have been in 10" pots for several years and have never gotten pot bound.  I prunned the excess roots and top growth, fed with Super Nova and Houseplant formula, and kept them in a mostly shady spot that received bright indirect light. In spite of this it died after struggling for a couple of months.  The other plant is Acapulco Gold.  While it didn't die it has never really recovered.  Growth has been weak since.  It's had regular doses of Houseplant formula and SN the last several weeks.  I also spray the foliage with SN about once a week.  I wonder if it is ever going to snap out of this?   It doesn't look awful in this picture, but it's basically looked the same for the last several months.  I'm hoping that it's replacing its roots and will explode with vigorous growth when the weather warms up.  Currently it's inside the house where it get about 5 hours of sun thru the south facing storm door.  What do you think?  I ordered a replacement plant during the store reopening just in case.  Also hoping you will have some more Pina Colada in the works as I'd love to replace that one.

Thanks,
dave

[davidwood]

Dave I have a couple of ideas about your AG having had similar problems, but first of does it look like that 24 hours a day [leaves looking a little limp], or when you look at it in the morning have the leaves  perked up quite a bit.

If above is true [perking up a lot in the morning] what I have found with AG is it seems to like the potting mix a little more compact [no idea why it just does] than others, to correct the mix and as I have mine in a big pot I used a broom handle but in a little pot like that you just need something like a wooden ruler, slide it down the side of the pot and gently force it inwards making your way all round the pot, adding mix to fill in the space you have created, this will compact it inside and does very little damage.

If the above isn't the case and its looking like that 24 hours a day then maybe its more serious, can you remember when you re-potted did you put back an actual root ball or where the roots lose, if they where lose I would say for sure that when you have re potted it  for some reason the roots haven't taken, a way to check is gently tug up the main stem, you may even pull it right out of the mix if your not carefull.
This problem can also be fixed but  I will hear what you have to say first.

[helixturnhelix]

Dave,

Its interesting how some CVs take being root bound much better than others.  There are several CVs, one that comes to mind is Climax, that just do not perform well in any pot that is smaller than 5 gallons.  In the ground is where these CVs really shine!  Other CVs are fine for years in smaller pots, its as much an art as a science figuring out which plants do well under which conditions.  Luckily the forum helps tease this information out little by little. 

[Charlie]

Dave, if the Acapulco Gold doesn't die I bet it will take off this coming summer. You could try watering from the bottom for awhile. Just fill the saucer and let it suck up the water from the saucer. Probably have to fill it more than once each time but just keep refilling it until it does not quickly suck up any more water.

Charlie

[roadrunner]

The foliage drooping has been fairly consistent for the last several months and it's 24hrs a day.  I'm treading a delicate balance on watering here.  It's been taking a long time for the pot to dry out between waterings (over 2 weeks) and I don't know what's going on with the roots now. I've lost several plants when they've gotten into the dreaded decline state from apparently overwatering, even though I had backed off on frequency significantly. 

David it was repotted probably late May of last year.  All of the roots I trimmed off were coiled around the bottom of the pot. There was some root ball that held together but the majority of the root system was coiled around the bottom.

Chris I think you are right about some cultivars just needing more root space.  I've been trying to keep the max pot size at 10" because of space limitations, especially for overwintering them.  Frankly I never expected to have this many plants (just under 100 and counting).  Apparently a few will need to be moved up to 12" possibly even 14" containers.  It would be so much easier if they all could stay in 8" pots, not for watering, but for spacing issues.

Charlie I'm going to try your advice on watering from the bottom.

Thanks,
dave

[Charlie]

Dave, I should have added that the main reason to water from below is that the water is wicked up along the fibers of the potting mix and does not fill the air spaces when done this way. In other words you cannot overwater in the sense of drowning the roots by flooding all the air spaces and driving the air out.

Charlie

[Ernest]

Charlie, that's an interesting point about watering from the bottom. Years ago I had a large collection of cacti in pots and it was standard procedure for everyone in the cactus and succulent hobby to water that way. I would put a few inches of water in the bottom of a plastic bin and place  10-15 pots in at a time. This saved me a lot of time and conserved water as well.

Erny

[Diana]

I intend to prune the roots of my biggest hibiscus other day but still have some scare if I do it right.
Also I've read that better not to cut the middle of the root ball, is it true?
Well I painted at these pics what I mean
Is it better to cut the root ball the same like at the first pic or at the second?
Thanks in advance for the reply


 

 

[davidwood]

Interesting question Diana, I know I do it as in the first picture and I would also at the same time scrape away all that loose mix[say the top inch] at the surface, this gets rid of debris and maybe any insects so I have new potting mix top and bottom.