I think you probably mean Cordyline australis - new planting in a south west facing garden in London is the equivalent of planting in the Sahara desert at the moment. When you say you water every other day, I wonder how much - I suggest you leave the hose trickling at the base of the plant for an hour or so, then wait three or four days and water well again, as there's no rain forecast (or none worth having) this week, either by leaving the hose running on a trickle again, or gradually pouring 5/10 litres of water round the base. Continue with this until such time as we get some decent rain, and by that I mean a week's worth. Planting at this time of year when its very dry means its very difficult to keep the roots and the surrounding soil moist - if you think about it, the bottom of the roots will be a good six inches below the soil surface, so any water you add has to penetrate that far. If your plant is in open ground, specially if the soil is light, its not possible to overwater - any excess will drain away.

Also, if the plant was in a shaded are in the garden center--or maybe indoors--it may be having trouble adapting to the direct sun. Eventually, the new leaves will be fully adapted, and the old leaves will drop off, but until then, it will look pretty raddled.