For your specific (FL) application, and assuming brown vegetation/terrain to be uncommon, I'd suggest using straight Rit "Apple Green".  The reason for this is that doing so darkens the material the least, and also provides some green and contrasting pixilation.  Such contrast recedes the darker the dye used.  You can see the difference between the pouches dyed with straight Apple Green, and 4:1 Apple Green:Dark Green.  YMMV, of course.

BTW, short MALICE clips from Tactical Tailor can be used to replace the ALICE clips on the buttpack; removable and reusable.  I have come to loathe ALICE clips.

Be advised that my comments in this thread (with a few exceptions) are concerned with dyeing nylon field gear.  I've dyed a few ABU and ACU uniforms, with good (to me) results, but the main difference is that while using vinegar with field gear, one uses salt with nylon/cotton fabric, as found in uniforms.  Make certain to wash the uniforms with NON-Brightening detergent prior to dyeing.  Woolite is safe, and readily available.

Also, dyeing uniform fabric is different from dyeing nylon, where what you see is what you get.  Uniform fabrics always darken when wet, and this makes getting the right color much more difficult.  I strongly suggest having a thoroughly wetted uniform sample available for immediate comparison purposes, although I'm not certain that doing so will ensure you getting the exact color you want.

Good luck, and please post some pix.

My uniform items, both ACU and ABU, were bought used, and so I was able to make sure size was OK.  IOW, from the appearance of both uniforms, they had shrunk as much as they were likely to, prior to dyeing.  OTOH, I would certainly expect new, unwashed/unshrunk items to shrink; how much is hard to say.

Going by pic, is that what you wanted?

Yes, I was speaking to you.  Please try to stay away from Rit Brown dye when dyeing nylon field gear.  It might be fine for all-cotton cloth, but with Nylon field gear, a lot of red shows up.  Looks like the emerald green you used toned down the red a bit, so the stuff looks good, compared to the "Martian-red" nylon gear I've seen.

I suggest starting at the beginning of the thread.  I give lots of pix, and explain what dye(s) were used in most cases.  I specifically warned about using Rit Brown dye, and recommended using rit taupe dye instead.  No biggie, you didn't ruin your gear, as did I during early experimentation.

Marpat Desert is a pretty good desert pattern, as-is. I can envision it working reasonably well in non-snow winter, such as  brown fields and leaves here in CONUS.  If wishing a darker, browner overall color, consider dyeing with either Taupe of some form of light brown to achieve an overall Coyote Brown.  Make sure to understand the rules for dyeing cotton/polyester cloth, as found on Rit Dye website; such ruled differ greatly from rules for dyeing nylon field gear.  As with over-dying any pre-existing camo pattern, the lighter segments will absorb the dye most readily, and the darker the pixel, the less the absorption, and the less the change.  This sort of variable-dyeing due to a pre-existing pattern can be seen when comparing the various UCP-pattern gear, whose pix are in the earlier part of this thread.

There is another point, which illustrates but one of the many differences between dying nylon field gear and cotton/poly uniforms.

Aside from adding vinegar to solutions intended for nylon field gear, and salt to cotton/poly clothing, that is.  Don't forget that essential, and important difference.

With Nylon field gear, making a solution highly-saturated with dye is not usually a problem, as long as the dyer realizes that with nylon, what you see is a tinch darker than the dry result, and pulls the gear before it gets too dark.  Fairly simple:  Dye some gear, pull it when desired effect is achieved, add more dye, repeat process.  Simple.

With cotton/poly uniforms/clothing, the saturation of the dying solution must be controlled to a much finer degree.  The material naturally darkens to a great degree by being wetted with water alone, and so this masks the effects of the dye.  Too much dye, and the clothing, which takes the dye almost instantly, is too dark.   With the case of cotton/poly material, the material takes the dye so fast that pulling it is not usually an option.

So, and with the understanding that I am NO expert in dyeing cotton/poly material, I would suggest that the dyer start by using disposable items of identical material/camo pattern as test items, and dying them with rather light concentrations of dye.  Remember that it is always possible to dye darker, but never possible to dye lighter than the original material.
A number of subsequent dyeings, with small, but progressively higher concentrations of dye, should allow one to reach, in stages, the desired color with cotton/poly material.  I'd dye a tinch darker, and reckon on some of the dye eventually washing-out, even if a dye-fixer compound (available from Rit) was used.

Frankly, all the USMC Marpat is likely to be replaced by (USMC-LOGO-ed) Army Multicam clone camo patterns, including Desert Marpat.  I'd leave the Marpat items alone because they will no doubt become collector's items in due course.  Collectors love genuine USMC stuff.

YMMV.

Should be do-able; I'd use the same, gradual, approach as outlined above.  You can find some worn-out UCP uniform items on which to experiment for cheap.

Keep in mind that new, or near-new uniform cloth will shrink due to the hot water used when dying.  So plan on the sizes of the uniforms changing as a result.

Non-GI nylon material takes the dye in unexpected ways.  If that was a GI Assault Pack, the outcome might well have been different.  The plastic buckles will accept a little of the dye; almost not enough to notice except of compared side-by-side with an undyed buckle.

I don't know if that's your desired outcome, but I've seen much worse for sale in stores, and almost anything is better than UCP.

Concur.

Re-read the thread if dying uniform items; the process is different than dyeing nylon gear items.

Never tried it.  At some point, depending on bleach/water concentration vs. exposure time, the bleach will begin to damage the cloth

Looking at this again, and certainly no offense intended to poster, I think it's overall too dark, and there is insufficient difference between the lightest pixels, and the darkest ones. I have come back to the simplest procedure, which is to dye UCP nylon gear with 4 parts Apple Green and one part Dark Green.  See the pix far above, and see the results.  For camo to be truly effective, there needs to be some sort of contrasting "break-up" of colors/patterns.  YMMV.

OTOH, it's better that UCP for any green environment than the original, so there is that to consider.

Some day, original UCP field gear is going to command stupid prices from collectors.  My making dyeing threads is driving such future prices up.  They should pay me for driving up the value of their collections.

After some time has gone by, and after further experimentation, and much thought given to the topic of dyeing UCP nylon gear, I have come to the following conclusion.

First, some background.

The original UCP gear has 3 different pixels.  One light, usually very light tan or even white,  a medium pixel always of the usual Foliage Green, and a dark pixel, always of a very dark version of Foliage Green.

This camo pattern is an excellent one to use when viewed by an opponent using Night Vision Gear.  Other than that, unless coated by dirt, it's a terrible pattern.  When deliberately 'dirtied-up", it's passable, in some circumstances.

The camo pattern relies on the disruptive pattern of the light/med/dark pixels to work.   In short, the contrast between the different shaded pixels IS the camo pattern.

If dyeing these nylon gear items, please keep in mind that the lighter pixels will "take" the dye much more readily than the darker pixels.  Since it is necessary to maintain a distinction between the light/med/dark pixels, in order for the camo pattern to work, it is necessary to dye the item in such a manner to leave the lighter pixels with a trace of the desired tint (Green/Brown), but to NOT dye them too dark.

Less is More.  Dye the item to desired color, but I suggest that a lighter dyeing will maintain a better contrast and better camo effect than a darker dyeing.  One can always re-dye to a darker shade, but NEVER to a lighter shade.  The contrast is KEY with the UCP pattern.,  YMMV.

Based on my experiences, I say the following; Take it for what it is worth, since I have NPT tried to replicate the colors/camo patterns specified above.

As always, the lighter pixels always take more dye than the darker pixels.  In some cases, such as with Apple Green, the lighter pixels are still light, and the medium and dark UCP pixels also take the dye to varying degrees.  This maintains the contrast, which is an essential part of the camouflage pattern.  In many cases, over-dyeing can yield a decent overall color, but the breakup pixilation of the original pattern will be lost.  Your call.

Remember one IMPORTANT point:  It is always possible to dye darker, if the initial result is not what one desires.  It is impossible to go lighter than what one has initially.  So go easy at first, and re-dye to suit your desires.  Take notes, and soon you will be an expert.  There are still batches/lots of UCP grenade pouches for sale cheap, and such make great experimental items.

Another IMPORTANT point:  Most of the tips on the Rit Dye website are concerned with dyeing cotton fabric, not nylon field gear.  A Brown dye, perfectly acceptable for cotton clothing, comes out Martian RED on nylon field gear.  I use Taupe for dyeing brown, instead of Red, or Tan.  The point is to experiment on discardable items before dyeing something valuable.

1) Black Multicam.  I think I'd experiment with some light grey dyes, suitable for nylon.  That will give the lighter pixels a slightly darker cast, and darken the medium and dark pixels a bit.   I don't know how the webbing will take the dye.

2) Wolf Grey.  Find a Dye that gives a light/medium gray cast.  Experiment. I think that with the right dye, the lighter pixels in UCP will take the dye, and come close to matching the medium and darker ones.  Done right, probably a better camo pattern than UCP or Wolf Grey, although pixelation will still be present, and IMHO, this is desirable.  If you don't want this, then re-dye, and accept that a darker grey than Wolf Grey will likely be the result.

Multicam Tropic.  Straight Apple Green will probably give the best results in "greening-up" UCP while maintaining/accentuating contrast.  Some examples of dyeing UCP with straight Apple Green can be seen near the beginning of this thread.

It's worth mentioning that someday, Excellent condition UCP gear will command collector's prices, because it was not long issued.  Perhaps hanging on to Excellent condition UCP gear, and selling it to a collector in a few years might be the smart move.  Even now, 3-color and 6-color USGI Desert camo pattern stuff is rising in price, and such items were also issued in limited numbers/amounts.  Condition is everything, but the amount issued (scarcity) is right up there, too.  Your call.  As a former collector of USGI field gear, I say that collectors will pay remarkable prices for good to excellent condition gear. Just depends on waiting till the right time, and putting up the gear for sale on Ebay or similar.  Trust me on this.