Forum home Fruit & veg

Vegetables in planters using polystyrene cubes as bottom filler

Hi All, I have this large plastic tug that I was using to grow on some canna plants a few months ago and just used some polystyrene chunks I had in order to basically fill out the bottom of the container. After moving the cannas to their homes I had some spare tomato plants left over so I basically chucked them in feeding them occasionally. However they have done quite well and some are now ready to pick, but I’m not sure that they re actually ok to eat as I’ve never been convinced by the polystyrene being safe to use with vegetable growing. If anybody has any thoughts on this I’d appreciate the input I’ll include a couple of pics. Thanks.


  • LynLyn Posts: 23,082
    Can’t see why not, a lot of foods you buy in the SM are packed in plastic trays and bags. 
    Gardening on the wild, windy west side of Dartmoor. 

  • FairygirlFairygirl Posts: 54,353
    I often use it at the base of large containers. That includes ones with edibles in them  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Blue OnionBlue Onion Posts: 2,987
    Yes, you are fine to eat them.  In future, you can use plastic soda bottles in the bottom as a filler instead.  The personal sized ones.  Rinse them out and then put the lid back on tight, and lay them across the bottom.  It is food safe plastic, and far easier to reuse than the styrofoam.  The roots grow through the styrofoam and it's fiddly to separate from the soil at the end of the season.  I even half crush and then put the lid back on plastic milk jugs for the base of my house plant pots to reduce weight, soil, and increase drainage.  
    Utah, USA.
  • Thank you all, seems like it’ll be fine , I’ll also try the bottle suggestion next time I fill a large container for planting. Seems ideal. 
  • pinutpinut Posts: 190
    The only two "safe" plastics you should in the garden are polyethylene (PE) and polypropylene (PP).

    Under controlled storage conditions like in your home and in warehouses, the other plastics may safely be used for food storage. However, outdoors, under sunlight, wide temperature variations and possible exposure to chemicals from the soil and rain water, these other plastics may leech/offgas into the soil.

    OP, I am guessing that your translucent container was not manufactured with added UV inhibitors and consequently won't last up to the two year mark. It will glaze over and crack into pieces in a few months time.

    When buying plastic containers intended for outdoor usage, go for dark colours such as black as they have been proven to last the longest.
  • Several years ago I used broken pieces of polystyrene as drainage in the bottom of large ceramic pots, for shrubs etc. I found after a few years the pots began to flood so emptied them out to repot the plants. The polystyrene had gradually compacted down into the drainage holes, thus blocking them so I have reverted to using crocks.
    I wanted to use polystyrene crocks to reduce the weight of the planters to reduce the weight of the pots when I needed to move them. 
  • FairygirlFairygirl Posts: 54,353
    I still use a crock or two in the bottom first @Joyce Goldenlily , then the polystyrene  ;)
    It can be a bit messy once it breaks down a bit, but at least it's being re used for a while instead of automatically going into landfill.

    I'm not sure the OP actively bought the container for growing plants in, but they last a few years, so again, better than being chucked in a bin once they start falling apart. Many places don't have major recycling facilities available either, so again - better to get as much use as possible out of these things. 
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Hi Everybody,
    After the tomatoes are finished (and eaten, thanks for that !), i'm actually going to empty the container and drop it into the wooden planter pictured behind the tub  basically as a liner to protect the timber.  Also I will be only using it with ornamentals  from now on as I only planted it with edibles as an afterthought and it seemed a waste to just throw it out as its in ok condition. Thanks for the feedback.
  • FairygirlFairygirl Posts: 54,353
    That's a good idea @TheSouthernGardener. It'll work well for several years in that space.  :)
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • I always add a load of polystyrene to the bottom of pots, admittedly,the ones growing veg are black. My oldest son uses protein powder,I take the containers. Someone said soda bottles,that's assuming anyone drinks "fizzy" drinks in plastic bottles.  Nope, I occasionally have a tonic water,it's in a glass bottle and goes in the recycling
Sign In or Register to comment.