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How do you know when to trim the roots?

Posted by MsGreenFinger 8 Ireland (My Page) on
Fri, May 16, 14 at 8:08

I have Ficus benjamina plantlets and they have grown long roots and almost no leaves. Should I trim those roots to fit in the pot or just leave them so the plants can focus on gowing leaves now?

Also, how do you know/estimate the necessary size of the root system?


Follow-Up Postings:

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RE: How do you know when to trim the roots?

Are these plantlets seedlings, or rooted cuttings, MsGreenFinger ?


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RE: How do you know when to trim the roots?

They are rooted cuttings, bought the 3 together, then I planted them into separate pots. Since they are in semi-hydro (clay pebbles, no soil) I think they have grown the necessary water roots. I just don't want them to do this, it's time to focus on leaves :)

This post was edited by MsGreenFinger on Fri, May 16, 14 at 14:31


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RE: How do you know when to trim the roots?

Ficus trees like to send long roots out right away, which poses a lot of problems for those in warm climates who put them in the landscape, due to the extremely aggressive roots. It also gives people grief who grow them in pots, that is, if you care to keep them alive more than a couple/few years. In pots, they tend to send roots right down to the bottom right away, which is where the moisture lingers. Not long after a repot, roots are popping out of the drainage holes already, but that doesn't mean it's root bound. I snip them off every now and again, otherwise they roll up under the pot.

As for what you should do, we'll, roots take up the water and nutrients, so if you're looking for foliage growth, you'll want those roots. If some are excessively long, you can nip them off, but I wouldn't get carried away. Good roots come before good foliage, so just be patient. As for rootball size, we'll, that's very subjective, because you need X amount of roots to support X amount of foliage, so it depends on how you intend to grow your tree. Right now, you're looking for rapid growth, so just provide for them, and as they outgrow the pots, pot up. During that process, I like to do minimal root pruning, but nip out the fatter roots if they don't take too much out. Letting the pot fill with fat, woody roots wastes space; you want feeder roots. In time, you'll reach your desired height and/or fullness.

Joe


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RE: How do you know when to trim the roots?

Thank you


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RE: How do you know when to trim the roots?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, May 18, 14 at 13:25

Potting up is sentencing your plant to a life of mediocrity, at best. Repotting, on the other hand, which includes a complete change of soil and selective root pruning, eliminates the limitations imposed by root congestion.

Your plant needs repotting (not potting up) when it gets to the point where the root/soil mass can be lifted from the pot intact. That is roughly the point at which root congestion begins to impact growth rate and vitality. If you're going to use potting up as part of your maintenance strategy, it needs to be done before your plant reaches the point where roots/soil can be lifted from the pot intact. If you allow your plant to get rootbound to beyond that point at any time, a repot is necessary to correct the limitations imposed by the plant becoming rootbound. IOW - once the plant has become rootbound, it will be limited, no matter how often or how large the pot when you do pot up, for the life of the plant or until the problem is corrected.

Al

Here is a link that might be useful: You might find this helpful.


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RE: How do you know when to trim the roots?

Al,
I have my plants potted in clay pebbles so I don't think they ever get rootbound. Or do they?
In this case is there any difference between soil-potted and semi-hydro plants about how much they fill the pot with roots before they have to be potted up/have the roots trimmed?
It's been only 2 months that they are in hydro so soon I'll need to check for dead soil-roots and that is kind of repotting IMO.

So you say that with smart root pruning, a large plant can live and thrive in a smaller pot? Or at least can stay longer in that without potting up. How do you estimate the amount of roots that are necessary for a healthy plant and how do you know when it's time to pot up?

Thanks for the link


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RE: How do you know when to trim the roots?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sun, May 18, 14 at 22:17

Eventually they'll get so root bound they'll start pushing the plant up above the rim of your pot, so you will eventually need to prune the roots. I suspect that root congestion in semi-hydro wouldn't be as limiting as it is in a solid medium because the entire volume of the container is available for root colonization - not just the interparticular air spaces.

One goal of root pruning plants in a solid medium is to remove the larger roots, which serve only as organs of transport. This leaves room for fine roots, the work horses, to grow.

It's not unusual for a bonsai practitioner to start with a plant in a 3 gallon pot and reduce the root mass so the plant fits in a much smaller pot - say a half gallon size. Here is an example of how extreme a root pruning of a healthy plant CAN be:
 photo repots010.jpg
 photo repots013.jpg

Another, a ficus:
 photo TooLittleRepot020.jpg
 photo TooLittleRepot022.jpg
 photo TooLittleRepot031.jpg

I have a LOT of experience repotting woody plants - I've done many thousands of them. For me, I can look at the volume of foliage and instinctively know how much root mass it will take to support the top mass. I take into account where the plant will be sited. If I really do a severe root reduction, the plant will be sited in open or dappled shade out of the wind (my houseplants are all outdoors at repotting time). For ficus, it's usually pretty safe to remove 1/2 of the root mass w/o having to prune the top back. If you remove 2/3 of the root mass, the plant might shed branches it can't support, so it's better if YOU selectively remove some of the foliage to prevent the plant from shedding branches that might be important to the plant's eye appeal.

If the root/soil mass can be lifted from the pot intact, it's already too late to pot up and expect to receive the same benefits you would from a repot. Growth and vitality begin to be impacted at about that pivotal point.

I wasn't clear on whether you were asking the recent questions about conventional container culture or semi-hydro. My reply was centered on conventional growing. Initially, I missed the part about this plant being grown in water - sorry.

Al


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RE: How do you know when to trim the roots?

Thanks for the input!

So I just chop off the thick woody roots and leave mostly the fine ones. Sounds easy :)


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