I think you're on the right track in your thinking, but for the sake of full disclosure:

- It's best to repot it in early summer. Technically not quite true. Summer STARTS Jun 21. In most locales, repotting should be done by then, but you can repot even i8n northern US States into Early Aug with good results.
- It needs fast draining soil no matter what and likes low nutrient content like in the gritty mix. There ARE work-arounds that allow you to use soils that would be wholly unsatisfactory w/o the work-around. Ballast, wicks, and several other tricks can be used to limit how much 'excess' water a pot can hold.
- I have to keep the fine roots wet during repotting. True
- It shouldn't be fertilised again until it starts new growth. True
- It's good to trim the roots 30% or more. I'd limit my first foray into root pruning to removing 1/3-1/2 of the roots, total ...... and I'd concentrate on large roots that are problematic for one reason or another and not connected to the base of the trunk.

However, I still have some newbie questions.

- I live in zone 10b (Malibu, USA). Should I still wait until June to
repot it? Can you manage to hold off until Memorial Day? That's when I would do it if I lived in Malibu.

- The soil. This is my biggest question. I understand gritty mix
would give my tree the most potential but I highly dislike the idea of
completely depending on plant food and watering as often as I've seen
gritty mix users say they have to water (every 3-4 days even). Is there
perhaps a different ratio or set of ingredients I could mix to give the
soil only a little less potential but a lot more leniency in those
areas? I wish there was a list somewhere of the detailed benefits and
pitfalls of different common soil ingredients. If you're going to do things to the gritty mix that eliminate the reasons you would go to the extra effort to begin with, push it to the back of your mind. It simply doesn't make sense from the perspective of economics or effort to make an expensive soil you might as easily have made with less effort and reduced outlay. I'd be thinking of something like the 5:1:1 mix, which is based on a high % of coarse ingredients, but still holds more water than the gritty mix.

- Root pruning. Again,
I'm new to plant care. How do you tell which roots are are healthy and
which are sickly or dead beneath the soil line? You'll know. Healthy = white or tan, not black, dark brown/ slimy.

Am I correct that I
should prune the large roots without a lot of feeder roots? Yes

What should I
look for beyond that? Roots that point back toward the center of the root mass, roots growing straight up or down, hooked/ encircling/ girdling roots. I've seen people straight up hack inches off the
rootball. Is that much removal and abrasion very beneficial to the tree
or can I just gently separate the roots and cut off obvious problem
ones? I alway start by hacking a significant fraction of the lower root mass off - often as much as 75%, but that's not meant as a suggestion to you. How much you can safely remove will come with experience. I was uneasy enough with root pruning as it was and then found
some even more disconcerting posts about how foliage may need pruning
also to a level the new roots can support. I definitely don't want to
prune my roots to a level near enough to likely need leaf pruning. It's
still a short tree and every leaf is healthy. FWIW - a ficus will alway benefit from pruning when you repot if you concentrate your pruning efforts at the top of the tree, which ALWAYS robs the bottom of the tree of its due, in terms of food and energy. I can say, without question, that if you continue to progress in your proficiency at growing trees in containers, at some point you will be regularly pruning at least the top of almost all apically dominant trees when you repot, for more than 1 reason.

- Keeping the roots wet. How do I do this? Should I keep a light
shower on them? Should I dunk them in a bucket of water every minute?
Could someone please suggest an exact method and interval to do this
right? I normally work over a tub of water and dunk the roots as often as necessary to keep them wet at all times. When it's cool/ humid/ shady, that might be every 2-3 minuts. Hot/ windy/ sunny = every 30 seconds or so. You can also use a hose & pressure nozzle to 'blast' soil off roots.

- Watering. Should I water it right after repotting? Yes

Does the tree
need to be kept in extra moist or extra dry soil before or after the
report? The fraction of soil that holds the roots needs to be damp - not wet or dry - damp. If your soil is appropriate, you can easily water a couple of times each day to ensure roots get enough moisture w/o suffering from soil saturation.

Also, I've seen mention of people soaking their ingredients/soil
before mixing/potting into it but I don't understand it. What's that
part about? Some soils, when they get dry, become hydrophobic (water repellent). To correct, make mud from about 1/3 of the soil you'll need for the repot, then mix in the dry soil. Do this well before you start the repot or transplant. By the time you need the soil, diffusion of moisture in the soil will have 'broken' any tendency toward hydrophobia.

- Fertilising. Should I fertilise some time before the repot? Give it
more strength somehow? Yes. Fertilize appropriately right up until the day you repot, and resume as sioon as you see new growth being pushed.

I bought some Foliage Pro 9-3-6 recently but
haven't been fertilising at all since I got the tree; just been giving
it filtered water. You should fertilize regularly all year long - varying the dosage and/or the intervals between applications in response to what part of the growth cycle your tree is in. I often fertilize at more than 2.5x the recommended maximum dose when cultural conditions support that practice. You can learn more about fertilizing containerized plants if you click me.

- Pot size. I read these trees enjoy small pots False. Read this. and can even be
repotted into the same pot after root pruning True

but I think mine is
pushing it. It's over 2.5 feet tall in a 6-inch pot. I'm definitely
going 8-inch minimum—but would it be better to go for a 10-inch?

How large a container ‘can’ or ‘should’ be, depends on the
relationship between the mass of the plant material you are working
with and your choice of soil. We often concern ourselves with
"over-potting" (using a container that is too large), but
"over-potting" is a term that arises from a lack of a basic
understanding about the relationship we will look at, which logically
determines appropriate container size.

It's often parroted that you should only move up one container size when
"potting-up". The reasoning is, that when potting up to a
container more than one size larger, the soil will remain wet too
long and cause root rot issues, but it is the size/mass of the plant
material you are working with, and the physical properties of the
soil you choose that determines both the upper & lower limits of
appropriate container size - not a formulaic upward progression of
container sizes. In many cases, after root pruning a plant, it may
even be appropriate to step down a container size or two, but as you
will see, that also depends on the physical properties of the soil
you choose. It's not uncommon for me, after a repot/root-pruning to
pot in containers as small as 1/5 the size as that which the plant
had been growing in prior to the work.

Plants grown in ‘slow’ (slow-draining/water-retentive) soils need to be
grown in containers with smaller soil volumes so that the plant can
use water quickly, allowing air to return to the soil before root
issues beyond impaired root function/metabolism become a limiting
factor. We know that the anaerobic (airless) conditions that
accompany soggy soils quickly kill fine roots and impair root
function/metabolism. We also know smaller soil volumes and the root
constriction that accompany them cause plants to both extend branches
and gain o/a mass much more slowly - a bane if rapid growth is the
goal - a boon if growth restriction and a compact plant are what you
have your sights set on.

Conversely, rampant growth can be had by growing in very large containers and in very fast soils where frequent watering and fertilizing is required - so it's not that plants rebel at being potted into very large containers per se, but rather, they rebel at being potted into very large containers with a soil that is too slow and water-retentive. This is a key point.

We know that there is an inverse relationship between soil particle size
and the height of the perched water table (PWT) in containers. As
particle size increases, the height of the PWT decreases, until at
about a particle size of just under 1/8 inch, soils will no longer
hold perched water. If there is no perched water, the soil is ALWAYS
well aerated, even when the soil is at container capacity (fully
saturated).

So, if you aim for a soil (like the gritty mix) composed primarily of
particles larger than 1/16", there is no upper limit to
container size, other than what you can practically manage. The lower
size limit will be determined by the soil volume's ability to allow
room for roots to ’run’ and to furnish water enough to sustain
the plant between irrigations. Bearing heavily on this ability is the
ratio of fine roots to coarse roots. It takes a minimum amount of
fine rootage to support the canopy under high water demand. If the
container is full of large roots, there may not be room for a
sufficient volume of the fine roots that do all the water/nutrient
delivery work and the coarse roots, too. You can grow a very large
plant in a very small container if the roots have been well managed
and the lion's share of the rootage is fine. You can also grow very
small plants, even seedlings, in very large containers if the soil is
fast (free-draining and well-aerated) enough that the soil holds no,
or very little perched water.

I have just offered clear illustration why the oft repeated advice to
‘resist pottting up more than one pot size at a time’, only
applies when using heavy, water-retentive soils. Those using
well-aerated soils are not bound by the same restrictions. As the ht
and volume of the perched water table are reduced, the potential for
negative effects associated with over-potting are diminished in a
direct relationship with the reduction - up to the point at which the
soil holds no (or an insignificant amount) of perched water and
over-potting pretty much becomes a non-issue.

Al

To answer one of your questions : yes there is an alternative to gritty mix, it’s called 5:1:1 and it’s also described in detail in many posts on this forum. Based on bark, perlite or pumice, and peat. It has more water retention than gritty but is still well draining so that may suit you better.

I keep the roots wet the whole time by either dunking in a bucket of water or working at them under a running tap. In the shade on a still warm day. It is important to remove all the old mix and then wiggle new mix into the gaps betweeen roots, but don’t get hung up doing a perfect root prune for your first repot.

My initial attempts ended up just being cutting maybe 20% straight across off the bottom before chickening out, and the plant police never came. Now I’m confident to remove a lot more, but I’ve never cut foliage back too - I wouldn’t want to on a nice looking plant like yours. Good luck.

Fennel - Reposted per your request. I hope you can see it. If not, send another message and I'll send it direct.I think you're on the right track in your thinking, but for the sake of full disclosure:

- It's best to repot it in early summer. Technically not quite
true. Summer STARTS Jun 21. In most locales, repotting should be done
by then, but you can repot even i8n northern US States into Early Aug
with good results.
- It needs fast draining soil no matter what and likes low nutrient content like in the gritty mix. There
ARE work-arounds that allow you to use soils that would be wholly
unsatisfactory w/o the work-around. Ballast, wicks, and several other
tricks can be used to limit how much 'excess' water a pot can hold.
- I have to keep the fine roots wet during repotting. True
- It shouldn't be fertilized again until it starts new growth. True
- It's good to trim the roots 30% or more. I'd
limit my first foray into root pruning to removing 1/3-1/2 of the
roots, total ...... and I'd concentrate on large roots that are
problematic for one reason or another and not connected to the base of
the trunk.

However, I still have some newbie questions.

- I live in zone 10b (Malibu, USA). Should I still wait until June to
repot it? Can you manage to hold off until Memorial Day? That's when I would do it if I lived in Malibu.

- The soil. This is my biggest question. I understand gritty mix
would give my tree the most potential but I highly dislike the idea of
completely depending on plant food and watering as often as I've seen
gritty mix users say they have to water (every 3-4 days even). Is there
perhaps a different ratio or set of ingredients I could mix to give the
soil only a little less potential but a lot more leniency in those
areas? I wish there was a list somewhere of the detailed benefits and
pitfalls of different common soil ingredients. If
you're going to do things to the gritty mix that eliminate the reasons
you would go to the extra effort to begin with, push it to the back of
your mind. It simply doesn't make sense from the perspective of
economics or effort to make an expensive soil you might as easily have
made with less effort and reduced outlay. I'd be thinking of something
like the 5:1:1 mix, which is based on a high % of coarse ingredients,
but still holds more water than the gritty mix.

- Root pruning. Again,
I'm new to plant care. How do you tell which roots are are healthy and
which are sickly or dead beneath the soil line? You'll know. Healthy = white or tan, not black, dark brown/ slimy.

Am I correct that I
should prune the large roots without a lot of feeder roots? Yes

What should I
look for beyond that? Roots that point back
toward the center of the root mass, roots growing straight up or down,
hooked/ encircling/ girdling roots. I've seen people straight up hack inches off the
rootball. Is that much removal and abrasion very beneficial to the tree
or can I just gently separate the roots and cut off obvious problem
ones? I
alway start by hacking a significant fraction of the lower root mass
off - often as much as 75%, but that's not meant as a suggestion to you.
How much you can safely remove will come with experience. I was uneasy enough with root pruning as it was and then found
some even more disconcerting posts about how foliage may need pruning
also to a level the new roots can support. I definitely don't want to
prune my roots to a level near enough to likely need leaf pruning. It's
still a short tree and every leaf is healthy. FWIW
- a ficus will alway benefit from pruning when you repot if you
concentrate your pruning efforts at the top of the tree, which ALWAYS
robs the bottom of the tree of its due, in terms of food and energy. I
can say, without question, that if you continue to progress in your
proficiency at growing trees in containers, at some point you will be
regularly pruning at least the top of almost all apically dominant trees
when you repot, for more than 1 reason.

- Keeping the roots wet. How do I do this? Should I keep a light
shower on them? Should I dunk them in a bucket of water every minute?
Could someone please suggest an exact method and interval to do this
right? I
normally work over a tub of water and dunk the roots as often as
necessary to keep them wet at all times. When it's cool/ humid/ shady,
that might be every 2-3 minutes. Hot/ windy/ sunny = every 30 seconds or
so. You can also use a hose & pressure nozzle to 'blast' soil off
roots.

This ^^^ fits on the hose end. Adding a shut-off helps save water.

- Watering. Should I water it right after repotting? Yes

Does the tree
need to be kept in extra moist or extra dry soil before or after the
report? The
fraction of soil that holds the roots needs to be damp - not wet or dry
- damp. If your soil is appropriate, you can easily water a couple of
times each day to ensure roots get enough moisture w/o suffering from
soil saturation.

Also, I've seen mention of people soaking their ingredients/soil
before mixing/potting into it but I don't understand it. What's that
part about? Some
soils, when they get dry, become hydrophobic (water repellent). To
correct, make mud from about 1/3 of the soil you'll need for the repot,
then mix in the dry soil. Do this well before you start the repot or
transplant. By the time you need the soil, diffusion of moisture in the
soil will have 'broken' any tendency toward hydrophobia.

- Fertilizing. Should I fertilise some time before the repot? Give it
more strength somehow? Yes. Fertilize appropriately right up until the day you repot, and resume as soon as you see new growth being pushed.

I bought some Foliage Pro 9-3-6 recently but
haven't been fertilising at all since I got the tree; just been giving
it filtered water. You
should fertilize regularly all year long - varying the dosage and/or
the intervals between applications in response to what part of the
growth cycle your tree is in. I often fertilize at more than 2.5x the
recommended maximum dose when cultural conditions support that practice.
You can learn more about fertilizing containerized plants if you click me.

- Pot size. I read these trees enjoy small pots False. Read this. and can even be
repotted into the same pot after root pruning True

but I think mine is
pushing it. It's over 2.5 feet tall in a 6-inch pot. I'm definitely
going 8-inch minimum—but would it be better to go for a 10-inch?

How large a container ‘can’ or ‘should’ be, depends on the
relationship between the mass of the plant material you are working
with and your choice of soil. We often concern ourselves with
"over-potting" (using a container that is too large), but
"over-potting" is a term that arises from a lack of a basic
understanding about the relationship we will look at, which logically
determines appropriate container size.

It's often parroted that you should only move up one container size when
"potting-up". The reasoning is, that when potting up to a
container more than one size larger, the soil will remain wet too
long and cause root rot issues, but it is the size/mass of the plant
material you are working with, and the physical properties of the
soil you choose that determines both the upper & lower limits of
appropriate container size - not a formulaic upward progression of
container sizes. In many cases, after root pruning a plant, it may
even be appropriate to step down a container size or two, but as you
will see, that also depends on the physical properties of the soil
you choose. It's not uncommon for me, after a repot/root-pruning to
pot in containers as small as 1/5 the size as that which the plant
had been growing in prior to the work.

Plants grown in ‘slow’ (slow-draining/water-retentive) soils need to be
grown in containers with smaller soil volumes so that the plant can
use water quickly, allowing air to return to the soil before root
issues beyond impaired root function/metabolism become a limiting
factor. We know that the anaerobic (airless) conditions that
accompany soggy soils quickly kill fine roots and impair root
function/metabolism. We also know smaller soil volumes and the root
constriction that accompany them cause plants to both extend branches
and gain o/a mass much more slowly - a bane if rapid growth is the
goal - a boon if growth restriction and a compact plant are what you
have your sights set on.

Conversely, rampant growth can be had by growing in very large
containers and in very fast soils where frequent watering and
fertilizing is required - so it's not that plants rebel at being potted
into very large containers per se, but rather, they rebel at being
potted into very large containers with a soil that is too slow and
water-retentive. This is a key point.

We know that there is an inverse relationship between soil particle size
and the height of the perched water table (PWT) in containers. As
particle size increases, the height of the PWT decreases, until at
about a particle size of just under 1/8 inch, soils will no longer
hold perched water. If there is no perched water, the soil is ALWAYS
well aerated, even when the soil is at container capacity (fully
saturated).

So, if you aim for a soil (like the gritty mix) composed primarily of
particles larger than 1/16", there is no upper limit to
container size, other than what you can practically manage. The lower
size limit will be determined by the soil volume's ability to allow
room for roots to ’run’ and to furnish water enough to sustain
the plant between irrigations. Bearing heavily on this ability is the
ratio of fine roots to coarse roots. It takes a minimum amount of
fine rootage to support the canopy under high water demand. If the
container is full of large roots, there may not be room for a
sufficient volume of the fine roots that do all the water/nutrient
delivery work and the coarse roots, too. You can grow a very large
plant in a very small container if the roots have been well managed
and the lion's share of the rootage is fine. You can also grow very
small plants, even seedlings, in very large containers if the soil is
fast (free-draining and well-aerated) enough that the soil holds no,
or very little perched water.

I have just offered clear illustration why the oft repeated advice to
‘resist potting up more than one pot size at a time’, only
applies when using heavy, water-retentive soils. Those using
well-aerated soils are not bound by the same restrictions. As the ht
and volume of the perched water table are reduced, the potential for
negative effects associated with over-potting are diminished in a
direct relationship with the reduction - up to the point at which the
soil holds no (or an insignificant amount) of perched water and
over-potting pretty much becomes a non-issue.

Al

Could someone please direct me to the detailed instructions on repotting a FLF? I've looked at many posts and they all seem to refer to other posts and I can't seem to get to the beginning of it all! My FLF seems to suffer from overwatering and now that I've read the tip about checking the soil with a chopstick I think my soil is too moisture retentive. It takes two or more weeks for it to dry out.

And what is the gritty mix- can it be purchased?