Planters on balcony

GlasgowExpat2

I’m going to buy 3 x 50cm cube zinc planters for my balcony - one will have a climbing rose and the others perennials. To reduce the weight and amount of compost I was thinking of putting some empty plastic water bottles at the bottom - is this a good/bad idea?  What type of compost should I put in the planters?

Devongardener

You could also use polystyrene blocks or loose polystyrene packaging, as long as you make sure you have enough depth of compost for the plants to thrive.
Any multipurpose compost will be OK, but it’s worth adding some slow release fertiliser pellets and keep them well watered.  Some perennials need quite a bit of space, what plants are you thinking of?

Green_hopeful

Fibreglass resin planters might be kinder to your plants. Metal gets hot in the sun. 

FlorayG

If you put anything non-organic in the planter you effectively have a smaller planter because the plant can't use that space. I'm sure there are composts specifically made for this purpose containing a large proportion of coir which holds water without becoming heavy. remember it can get very windy on a balcony as well; if your container is light at the bottom and top heavy it's likely to blow over

twopenny

How big wide tall are you planning to go?
What other plants? That decides the compost.

I think you need some specialist advise for this. 
Weight your balcony can take and what size you need for the plants you want to put in. 
Likely a small rose that won't have deep roots and similar.
They used to say polystyrene but I can't think that's good for plants so bottles may be better. However if it's light at the bottom and heavy on top with the high winds we get now and if you don't have the right balance the plants will be blown out.

Your idea is fine for small low growing plants but for anything more adventurous you need a lot more detailed advice.

Be prepared for watering daily at least once.

-taff

Have you got a solid balcony or a metal type one? If the former, don't worry so much bout them blowing over. If the latter, you can still use plastic bottles or whatnot, drill a couple of holes in the planters and zip tie to the balcony and also connect the panters together with a bolt or two if you're using in rows.

Either way, the watering lots is spot on because it's windeier the higher you go, and potentially warmer/colder so pick plants that will withstand a bit of weather.