What a nice collection of plants you have. Why not wait a while before repotting your citrus, until it blooms...let it do its thing and allow it to get adjusted to its new home. I imagine this plant likes plenty of light and hope you have placed it in a bright room/window. Also, it would do well with a humid atmosphere (like the topics), so spray its leaves with a fine mist early in the day. Do things gradually and observe what the plant seems to like, what it responds to. They're like people you know (lol).

You could root prune a spider plant with a weed whacker and it would be fine afterwards. Start with those if you're feeling nervous, or have specific worries about being too rough with exposed roots.

The steps as I understand it are:
Remove plant from pot
There's often another step after this, which is 'chop off the base of the pot-shaped rootball'. It's sadly common that you'll see lots of circling roots around the bottom of the pot, and there are several reasons to carve the rootball like a turkey before you do anything else at all.

1. You're quite likely to damage them if you try and untangle them, and then you'll just have to remove them anyway.
2. The thick, relatively unbranching roots are the ones that ferry collected nutrients to the top part of the plant. They don't do much collection themselves, and the woody ones don't do any. In a pot, all they do is take up space.
3. They get in the way when you're trying to take the rest of the soil off, especially if they're woody and have woody corners.
4. They get in the way when you're trying to repot, especially if they're woody and have woody corners.

Overall it's a lot of effort for very little return, and takes time you might not have. It's less traumatic all round to lop them off and be done with it.

If the plant isn't pot-bound, great. Straight onto the next step.

Remove as much of old dirt as possible
For this you can use a root rake, a chopstick, a jet of water, or your fingers. Whatever you use, take care not to scratch the skin on the roots. Some species tolerate that more than others, but no species likes it.

Cut off dead roots, roots growing in a circle around the pot
You can do this as part of the previous step. As you're taking the soil off, remove roots that are circling, dead, heavily damaged, or just plain long. These long roots are more trouble than they're worth, being hard to keep undamaged and requiring their own special space in the new pot. You can also cut off old woody roots that are getting in your way, if they don't have many fine roots at the end. You may need to take off a swathe of old roots near the base anyway, so you can get all the soil out of the very centre of the root ball.

You may also need to take off another layer of bound roots, if the plant was previously potted up while rootbound. Cut a slit in the corner of this new rootball, going directly through the bundle of roots, and make as many cuts as you need to get access to the interior of the old pot.

Once you're done with that, tidy the roots up. Take off root sections that have a single deep wound / multiple scratches, have ends that curve upwards or back towards the plant, have no fine roots branching off near the end (NB: change where the end is; don't cut the whole root at the base!), or cross over other roots. While it's best to correct all of these problems, at this point you may not have many fine roots left. Take the worst offenders, or the ones that are crowding more desirable roots, or the ones with lots of mass but hardly any fine roots, and leave the rest for next year.

Cut wedges out of the root ball (this is the one that makes me really nervous)
Not always necessary, and redundant if you're bare-rooting. Bare-rooting (and the subsequent pruning) creates space for new, fine roots by removing unwanted roots and sections of unwanted roots while leaving as much fine rootage as possible. Wedges create space for new roots by bulldozing an area of the existing root system, from the thickest roots down to the thinnest and without regard for whether or not those roots are entirely inside the wedge taken. That's not to say wedges are bad -- while the effect on the worked area is... dramatic, the rest of the roots are left undisturbed.

Add gritty or 5-1-1 mix to new similar-sized new pot, or well-cleaned old pot
Settle plant in new pot, water thoroughly
Do not fertilize for awhile (not sure how long)
Fertilise when you start seeing new growth. That means the plant is taking up enough water to do more than keep itself turgid, and you can start making osmosis a little less easy by adding fertiliser salts. How long does that take? Depends on the current health of the plant, the potential vigour of the plant, the time of year, and the conditions the plant is exposed to after being repotted.

Timing IS important, and depends on what plant material you're working with. Spider plant & ficus tree - late Jun or early Jul, miniature rose - before buds break in spring, calamondin and meyer lemon - early spring.

You can get away with a LOT if you keep the roots moist, use a good soil, and provide reasonable after care.

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Al

Great! I got on here to find a topic already started for me, that Al has commented on, with a perfect illustration! Al, when do you know when its time to repot? I started my key lime 3 years ago in a 2 gallon (about?) terra cotta pot. I live in North Iowa, so it hasn't been growing continuously. It is finally starting to really sprout. I've kept it in check over previous winters and pretty much chopped off all the leggy growth before springs. However, the past 2 months this thing has exploded! It is growing like crazy, even in the limited amount of light I've been able to give it. Do I let it really grow this year and establish itself, or do I root prune it now that it is healthy and strong so the taperoot is taken care of and it can grow to maturity in the next 3 or 4 years? I'm on the fence. I know root pruning will not set it back very far, just want to make sure I don't do it too early in its life.

If you can lift the plant from the pot with the root/soil mass intact, your plant will benefit from a repot. Sometimes, even if I know the plant will be a little too root bound before the next opportunity to repot, I'll still skip & let the plant suffer a little loss of growth/vitality, but I always repot at the next opportunity.

The healthier your plant IS, or the healthier it WAS when it went dormant, the more roots you can remove. Err on the safe side when you're just getting familiar with root work though.

Al

Sounds good. I have roots coming out the bottom of my pot and substrate falling out too since my screen fell out a few years ago. Maybe I will just let it grow this year since I doubt it is root bound. I pulled on it a little and the substrate moves up, but not like I would imagine that tree in your picture does!.

Wow, thank you all for the great advice!

Canukgirl, the citrus are currently in the east window, and will be moving to the south windows as soon as I'm sure they didn't bring home anything too icky from the greenhouse. They get misted, and sometimes even have a humidifier :)

Sutremaine, that is exactly the kind of detail I was hoping for!

Badsmerf, you're welcome ;)

Al, that's amazing! It's one thing to hear it, and another entirely to see it. Thanks too for the advice on timing.

And here's a picture of my little rosebush, since she decided to bloom today.

Whoops, just thought of a follow-up if you're still watching Al, (or anyone else who knows) - when should I re-pot Arabian Jasmine and Christmas Cactus? Or even better, where can I find this information on when to re-pot various plants for myself?

Sutremaine, that is exactly the kind of detail I was hoping for!
Thanks -- it was helpful to me as well, as it reminded me of wedge-cutting at a time I was dealing with a new Forsythia. The roots on that were all long transport roots leading straight into an open brillo pad of fine roots throughout the pot, and trying to pick that particular root structure apart tends to create moments of frustration that ruin the careful work already done.

I don't have any experience with jasmine, but some poking around Google suggests that it should be repotted late winter / early spring, just before the top half of the plant starts moving. I do have experience with Christmas Cacti, but while I don't kill them I can't really get them to grow either. Cacti as a whole should be repotted just before they start growing for the year. The common wisdom for this is that it's the only time of year at which the roots are dry enough to not rot from any damage caused at repotting time. I suspect there are other reasons for preferring bone-dry roots at repotting time, but I'll need a couple more years of observation to start working that out.

If you want to learn about the best time of year for repotting (or pruning), do some general reading on how energy flows up and down the plant as the year goes on. I'd also recommend taking a look at bonsai techniques, because they're refined enough to keep a plant healthy in a small container for decades. And the thing you're trying to do here is keep a plant alive and flourishing in a container for as long as possible, right?

Repot the jasmine in the fall after the bloom period ends, and make sure you protect the roots from freezing if you give it a cold rest. I'd repot the CC in April, where you live.

Al