Hostas in containers.

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Over the years I have experimented with different compost mixes for growing Hostas in.  Bark, pumice, perlite, grit, vermiculite, rockwool, coir, garden compost, leaf litter, peat and soil in different combinations.
Soil is always good but getting a good supply is a problem and you never know the nutrient content unless you get every batch tested.  Soil on its own in pots is not recommended add grit at 10% to help open the soil up.
Coir was a disaster it has the habit of being dry on the surface but when you put your finger into the pot the bottom of the pot is really wet so watering the pots was a big problem and I got more root die back due to excess water.
Garden compost mixed with leaf litter and grit was good for the first two months then the plants started to suffer lack of nutrients and the compost got very wet and started to smell.
Rockwool was good on its own to start of young divisions of Hostas provided you could control the water and nutrients not for the amateur grower and only worked on young plants to get them started.
Pumice or perlite mixed with peat was the best and is what I use now as my main compost mix.  I add 20% perlite by volume to peat to this I add a slow release fertiliser and dolomite lime (magnesium lime) I now try to grow all my hostas on capillary mats outside and this mix works very well as it draws the water right up the pots so as the compost gets evenly wet but not waterlogged.  Too little or too much perlite can lead to the plants drying out to quick or becoming to wet 20% is the best I have found.  Using good grit the same ratio will work well but makes the pots very heavy to move around and also makes dividing the hosta roots more difficult.  With perlite the roots actually grow into the perlite and this allows air to get around the roots better as it acts as a tent over the fine root hairs trapping air pockets in the roots that have grown into the perlite.  Getting the right air filled porosity in your compost is a must for good root growth.
Make sure if using slow release fertiliser not to over do adding too much to the mix as you do not want to force the plants on too quick as this will lead to pest and disease damage setting in quicker as the foliage will be much softer and more prone to attack.  I only use 412g or about 12 ounces to 100 litre bale of peat to this then add 247g or 7 1/2 ounces of dolomite lime per 100 litre of peat. 
It is still hard to avoid using peat in the compost mix to get optimum growth fine composted bark will work but your fertiliser needs to be increased as there is a higher c:n ratio ie carbon to nutrient the more wood fibre in the mix the more nitrogen is required to break it down so any nitrogen in the compost goes to the bark instead off to the plant.  With bark mixes watering again is a problem they dry out very quickly.
I would be interested to know what other mixes you have tried and how they have found them working.  Hope this gets some discussion going.....
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