Insulating plastic planters
pariate
Posts: 77
Hi all,
We have a tiny terrace outside our kitchen door. The short version of this story is that we now lots of shelves which will hold pots, they're very strong but I don't want to tempt fate so I have opted for plastic containers to keep the weight (and the cost, come to think of it) to a minimum. The containers are troughs, measuring 70cm L, 30cm H, 25cm W with a capacity of approximately 32 litres. The majority of these are on shelves on an east-facing stone wall, a few feet up with no shadow of any kind sheltering the pots until the sun has moved behind the wall. One of the plants I would like to use is a small clematis and because I've often heard people say that clematis in containers need a little shelter around the roots I started thinking about ways of insulating them. I've read about double potting and had what may be an absurdly convoluted plan...
Rather than try to find pots which will fit inside the existing ones without sacrificing too much soil, could I plant the plants in a big grow bag, pop the grow bag inside the plastic pot with either chippings or even just some polystyrene packing sheets between the wall of the pot and the grow bag?
Is this overkill? Totally unnecessary? Or is it actually a sensible idea? I've always had a lot of container grown plants (permanent plantings of shrubs and climbers rather than annual displays) but up to now I've used thick, heavy, glazed pots. I'm a little anxious about planting up small shrubs and climbers only to lose them later on in the year.
IF this is a sensible idea, is it also going to help protect the roots in winter?
Posts
I wouldn't put a clematis in a container that small. They're hungry, thirsty plants and you'd struggle to keep it happy. Better to stick with smaller plants which will cope, and you can move into a sheltered spot over winter if you have a really cold spell. Things like aubretia, which will cope with drier conditions but are hardy, would be ideal. Trailing ivies, small bulbs, dianthus and small hebes would also be fine, and pelargoniums for summer will also do well. If you have an idea of colours and types of plant you like , you'll get more suggestions. You'll still have to be vigilant with food and water.
If you really want a clematis, and can't put it in the ground, get a big pot to put it in and position it against the wall.
I live in west central Scotland - not where that photo is...
Okay. I got my hopes up because my pseudo mother-in-law has the most insane luck with growing climbers in containers. She's got a few clematis plants in pots pretty much the same capacity as (if not smaller than) the ones I described. They do really well year after year. She has an excellent camellia in a pot probably only 12" diameter, the plant is enormous, evergreen and has been flourishing for years. Her honeysuckle again is in relatively small pot but thrives. Because of this I've started to be a little more optimistic about the idea of planting climbers in containers.
Not saying you can't grow them in containers pariate - but you'll make quite a lot of work for yourself. I've had clematis in smallish pots - 12" diameter - and they've been ok but in long hot spells (yes - we do occasionally get them up here!) you're constantly having to check they're alright and not parched. I always had to arrange stuff round them to shade them and so on. East facing might not be so bad as you'll miss the mid day heat.
Try one in a big pot and see how you find it - depends how brave you want to be
I live in west central Scotland - not where that photo is...
That's why I started to think about ways of insulating the planter, to avoid the issue of lack of external shade.
Stones can be a double edged sword - they give shelter to slugs and snails, a big enemy of nice new tender clematis shoots. Gravel, or a similar mulch, will help prevent evaporation though. A decent sized, solid pot will be fine for a deeply planted clematis that's east facing. It won't be so vulnerable as it will only get morning sun. The trough raised up would dry out much more quickly than a large pot on the ground. Working with your plants will always be more successful than trying to make them conform.
I live in west central Scotland - not where that photo is...
Taylors, a company that supplies clematis recommends the minimum size of pot for a clematis is 18" deep.
I'd be grateful if someone could still give me their thoughts on the basic principal of insulating containers in this way. Set aside anything you may think about my choice of plants because that's flexible - I need to know about the insulation.