Also, what are some people's favorite compost recipes?
This can vary considerably depending on how much you know, but it's best to start with a decent base compost to start from, compost companies spend millions on getting their compost recipes right, why do we think we can do better?
Having said that the Miracle Gro composts don't appear to grow Canna particularly well. Fox Farms organic soils seem to be quite popular though, can't say myself because I've never used it.
Find a decent organic commercial compost and work on amending it for outdoor grows. Amendments could be come horticultural grade sand and/or gravel to help drainage and aeration, say up to 10%. Worm castings helps with primary nutrients particularly Nitrogen and trace elements, say about 10% again and/or bat guano similar to worm castings different NPK ratios again about 10% or 5/5% guano/castings.
Dolomite lime can help with ph buffering and Calcium and Mg and Calcified seaweed can help with Mg and trace elements as well as feeding the soil micro-herd. Both at about 1 level tsp per L of soil.
So a mix of something like -
80% Organic Compost
Horticultural sand 10%
Worm Castings 5%
Bat guano 5%
Dolomite lime 1 level tsp per Litre of soil
Calcified seaweed 1 level tsp per Litre of soil
Would do quite well for an outside grow I think. Also consider adding 'beneficial funghi' like Mycorrhizal when you plant outside as this can substantially enlarge the plant root mass increasing water and nutrient uptake efficiency and helping to convert organic substances into plant useable nutrients.
Hope this helps get you thinking in the right direction.
