Lots of folks use the 5:1:1 mix: 5 parts Orchid Bark (the very small piece type of Orchid Bark), 1 part Perlite, and 1 part Peat Moss.

Or "Al's Gritty Mix" 1:1:1:
Turface (calcined high-fired clay). It is very porous and used in the soil to hold water and nutrients. Look for size "Turface MVP" or "Turface AllSport" at John Deere Landscapes dealers. The products are identical.

Granite grit. It holds no water or nutrient, except as a film on its surface. It is used to provide better drainage and reduce water retention. For brand "Gran-I-Grit" use 'grower size'. If you can find New Ulm cherrystone, use #2 size. For other brands, the ideal size is 1/8".

Fine bark. It is used to hold water and nutrients. Use uncomposed "Fir" or "Pine" bark. Ideal size is 1/16" to 1/4".

You should also add in gypsum as a CaSO4 source. Add 1 tbsp to every gallon. Because gypsum contains no Mg, use Epsom salt for MgSO4. Use 1/8 -1/4 tsp Epsom salts per gallon of fertilizer solution each time you fertilize.

And, a Meyer Improved is a Lemon, not a lime :-) The most delicious lemon you'll ever grow, btw, and makes the most superlative lemonade ever. I have a lovely Meyer Improved Lemon tree in my garden that I rescued and revived. The previous homeowners, while great gardeners, struggled a wee bit with fruit trees. Here's my Meyer right now, with about 100 lemons ready to go:

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Patty S.

I have a Dwarf Meyer lemon in a pot (18" diameter) which is now nearly 20 years old. It grows in John Innes no 3. and gets repotted every 5 years or so. I don't know if these are available in the States, but it certainly suits my lemon.

Here is a link that might be useful: John Innes composts