What compost suitable for pots etc?

Hi Guys,
Can anyone give me advice on above heading?
In the past, compost I have used , seemed to compact ,& I need to make some of my pots a long term planting, like bridle wreath spiarea?[spelling?] & other shrubs.
Thanks for your time.
Jackie&Bob

 

I use general purpose compost for most things, including pots, but I put crocks at the bottom, or broken up polystyrene, and add a few handfuls of perlite to the compost to help it drain, and add osmocote pellets.

http://www.scottsukonline.com/products/plantfeeding/osmocotetabs.html

Oh, and I always stand the pots on pot feet or bricks, to keep them off the ground. They're less likely to crack in the cold, and you get fewer invaders from below.....

 

Hi J&B. I would agree with Dendro for normal pots. I use general purpose compost with about 30% sharp sand to help drainage.

However I understand that over time compost decomposes into smaller particles and reduces the drainage. This effect is small over a couple of years, but after three or more years it can become serious. In this case I think you want a soil based medium. I have read about this on an American forum, and they have special 'crushed rock' based compost (sounds like sand!). Without access to this sort of sophistication I would use good garden soil. A big shrub like spirea will need the extra weight for stability.

 

I use a 50/50 multipurpose and john innes no3 it doesn't dry out as quick as the peat based composts do it adds a bit of weight to the pot as Peter points out,helps stop the pots being blown over

 

Thanks for your advice, will give it a go this year, maybe get better luck.
Cheers Jackie&Bob

 

If your going to use some as long term planters, then don't forget that they will need to be revitalised each year. For me, I use multi purpose and vermiculite with slow release Osmacote or similar - as Dendy. Each year I remover the top inch of compost and replace, lightly forking in some more osmacote at the same time.