Does anyone know if placing a raised bed off a brick home in warm climate would do more damage than good to the plants? My landscaper warned against it because he believes the heat radiating off the brick would be too much for the plants. Thoughts?
I have a raised bed directly up against the concrete foundation of my garage.
A little background information: The garage is on a small hill, so the foundation is about three feet high; the raised bed is against two feet of the foundation, with one foot exposed above it. Above that is a dark-green wooden clapboard wall. The bed and garage are in full sun, getting at least 8 hours of sun a day in the summer. I live in Wisconsin, with high temps consistently in the 80s and some 90s throughout late June through August.
The only concern I've ever had with this arrangement is of concrete leaching causing increased alkalinity in the soil, which so far hasn't been a problem. I've never had an issue with too much heat causing problems with my plants. In the late winter, the snow melts first in this bed compared to all other beds in the yard; daffodils and grape hyacinths bloom at least two weeks earlier there than anywhere else.
One other note - I only water this bed when I water the rest of the vegetable garden to its south, as it doesn't appear to be any drier than that garden.
Now, my climate is not yours, but I would suspect your only issues would be increased need for water in that bed, so be sure to mulch it well with an organic mulch of some kind and keep an eye on it for any additional watering.
A bigger issue for you may be water from the raised bed eroding the bricks of your home and/or the mortar between the bricks, as not all bricks are meant to be below ground level. If the mortar becomes cracked/crumbly, you risk allowing rot behind the bricks which could cause damage to the sheathing behind the bricks and, over time, potentially cause structural damage to the joists behind the sheathing.
Finally, if you're in termite country and if your bricks are only covering a poured foundation, then you risk providing an easy path for termites into your home by putting any soil that close to the siding of the house. If you have a brick house and wooden window trim (particularly if you have basement windows), you're also at risk of a termite infestation.
It is difficult to imagine a problem for plants . As noted by @ Jurp ,you may have a slightly warmer micro climate / a mini mini heat island. I am in Zone 8 ( warm ) and see no difference for plants in the ground near brick walls ( same when I lived in zone 5). The concrete patio ( south exposure) provides some warmth for pots in cold or freezing weather. In summer ,pots are in shade on a wood deck . It would not be good to put any raised bed soil against a brick house wall : here there are vent holes in the bottom brick course , also termites , and deterioration noted by @ Jurp.