Suggestions for a Lightweight Filler Base for a Large Planter please.

[ladybirder]

I've got 4 fruit trees in pots which are too small. I am moving them into individual wooden cube planters measuring 60 X 60 X 60cm. Each planter will need 4 bags of John Innis No.3 compost to fill it up. As these will be very heavy and sit on a roof terrace, I need a lightweight filler for the bottom few inches rather than pebbles or crocks. I'm thinking about polystyrene balls, the sort of thing that you find in beanbags. Do you think they would be OK? They are waterproof I believe, but would they crush under the weight of the tree and compost, to end up in a solid mass which would stop the water escaping through the drainage holes at the bottom. Or does anyone have a better idea? Thanks.

[marden40]

If I remember right, I heard once that an ideal filler was the polystyrene pieces you use as packaging........those that look like wotsits or quavers.......but it was for plants I think not tree's, but I see your logic, and concerns.

[ladybirder]

Trees or plants same difference I suppose. All that packaging stuff I've thrown away marden and now I might have to go and buy some. Tut. Thanks for your suggestion - it will probably be better than the little balls.

[EcclesCake]

LECA (Light Expanded Clay Aggregate) might be better than polystyrene. You should be able to find it in garden centres.

[ladybirder]

Never heard of that, wouldn't that be heavy eccles?
Actually I've just come down from the roof terrace as a friend who has a shop brought a load of polystyrene packaging over so we've moved the cherry tree into its lovely big new home for life. Looks fab. It took 4 x 30L bags of JI3 on top of the polystyrene to fill just one planter. Don't anyone dare tell me it's in the wrong place!

[Frank97]

Clay pebbles are great for the bottom of pots
http://www.google.co....3881a558318d3eb&ion=1
a bit expensive though, but very light to handle, plus they can be reused if required. I use them for the bottom of my cacti and succulant pots, they provide excellant drainage.

[EcclesCake]

No, it's not heavy, imagine clay popcorn. It's the best way I can think of describing it.

[EcclesCake]

D97's link appears to be for the same stuff.

[ladybirder]

Yes thank you D97 and eccles. I've had a look at the link but as what I've got is free, then I'll wait awhile before I plant up the next one and see if there are any problems. If there are then I will come back to your suggestions as Plan B.

[woofgang]

be careful with a tall plant and a lightweight base. Top heavy plants blow over easily and continuously which is very annoying.

[nungate]

I used to use the polystyrene containers that the plants came in - broken up that way the planter was lightened a bit and the compost could work it's way down in the gaps between the broken bits of polystyrene as they were fairly chunky pieces so that the container wouldn't be too top heavy.