I have been told that roses do not like being planted in ceramic, clay or metal pots and that it is best to plant in plastic pots. Is this correct?
I first began planting roses in pots in the mid 1980s. I should add, all of my rose growing experience has been either in the inland valley heat of the Los Angeles area; coastal “coolth” of the West Side and Pacific Palisades area “at the beach” around LA and now on the California Central Coast between Santa Barbara and San Luis Obispo. Ceramic and terra cotta ARE “cooking utensils”. There are good reasons cooking pots are made from those materials. They heat quickly, transfer that heat to their interiors very efficiently and retain the heat for long periods. Plastic will heat as long as the sun shines directly on its surface, but once the sun moves off its surface, it begins releasing that heat and completely sheds it significantly faster than either terracotta or ceramic. The same goes for metal. Cooking pans and pots are made of metal for the same reasons. If you must use either of those three materials, you would do well to insulate their interiors with layers of styrofoam or many layers of large cell bubble wrap to prevent the rose roots from growing toward the warmth of the pot walls and circling them as they grow, exposing them to the greatest damage from extreme heat or extreme cold transferred from the exterior of the pot through the pot wall. In my experience, the best materials to use for pots in situations where there is going to be extremes in temperatures transferred into the root balls are concrete, foam or wood as all three have significantly greater insulation values than the ceramic, terracotta or metal. Foam and wood are lighter in weight like the plastic pots are while concrete provides the extra benefit of weight to help prevent winds from toppling the pot. But, concrete is expensive and that weight makes it a bear to move into position and probably completely unsuitable if you’re considering growing your potted roses on a balcony or roof top.
IF you are growing them potted in situations where the pots will be shielded from direct sun, ceramic or terracotta may suffice but any time the sun directly shines ON the pot surface, it WILL heat the roots and soil ball. If the conditions are hot and sun intense, it may be sufficient to damage or literally kill the roots. Whether it is or not, that extra heat will increase the amount and frequency of water you will need to apply and it will cause any time released fertilizers to break down and release their contents much faster which can cause salt damage if higher levels of the fertilizer have been applied. That extra heat and water will also cause your potting soil to digest and deteriorate faster as the bacterial action in the soil will be more active.
Of course you CAN use those materials, however to do it successfully, you need to be very mindful of their positioning and either insure you are using very large containers so the volume of soil helps insulate the plant roots; the interiors are sufficiently insulated to prevent extreme temperature transfer to the interior or the pots are completely shielded from sources of heat and cold. While you MAY succeed for a while, just as many succeed in pushing zones, Nature WILL catch up with you eventually. And she is unforgiving when she does.
Many thanks for the detailed response to my query. This is much appreciated and has given me much food for thought. I trust that others will also benefit from your in-depth response.
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You’re welcome. Thank you. I hope it helps. I continue growing roses in pots due to seismically engineered soil, physically compacted to near “bed rock” density which provides stability in case of earthquakes. It also nearly totally eliminates drainage (no air space in the soil) so all roots grow to the surface under the sod and planting holes fill up with water, rotting anything planted in them. The most successful are planted in 15 gallon nursery cans. The main issue is weight and bulk. Even in the milder, cooler climate here, compared to the old inland valley heat, potting soil digests in a few seasons and the plants require repotting. Hustling a 15 gallon root ball with the corresponding top growth can be a bit “cumbersome”, particularly as the “mileage” racks up. Something to keep in mind. Good luck!
Thank you. I have seriously enjoyed the science behind planting roses in pots. It is not quite as simple as what I thought it to be. I live in Lexington in Kentucky. The winters are severe and the weather quite varied. The locals (I originate from South Africa) say if you don’t like the weather wait 5 minutes and it will change. This is just what it is.
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You’re welcome. Given that information, I’d consider foam pots. They’ll insulate better due to the material. They’re lighter in weight, making moving them into garages for winter easier and repotting easier. Your choices of design and colors is fairly good these days so they can be prettier than the black plastic cans.
Many thanks once again. I seriously appreciate the time which have taken out to give me the advice which I was looking for. I will have a look around to see what I can get. Keep well!
You’re welcome! Thank you, you, too!