http://homeguides.sfgate.com/care-tristar-strawberries-45860.html says that
Strawberries grow as perennials in U.S. Department of Agriculture plant hardiness zones 3 through 9, depending on the cultivar and in zones 9 and 10 as cool-season annuals
Is it the heat that kills the strawberries (tristar) and prevents it from being a perennial? What should I do save my strawberry? Should I bring it inside the house in the summer or winter (it's in a pot)
Strawberries are perennials. Only problem is they are good for only 2-3 years. They are subject to soil-borne fungus such as verticillium wilt and botrytis. Viruses, aphids, slugs, snails and spidermites as well. You can take the new plants at the end of the runners and use those if the parent plant is healthy for the next crop. If your variety is an everbearing you need to replace every other year and June bearing every third year. Chose resistant varieties for your area and plant in a different part of the garden than your first crop. Or if in pots, clean pots with bleach and throw away the old potting soil! Repot with new potting soil, no gravel at the bottom!
Make sure that the crowns are above the soil...burying them too deep will kill your plant. I made this mistake! Definitely an annual if this happens...if conditions kill a perennial they sometimes call the plant an annual. Grin.
Strawberries in pots should be taken out and planted in your garden for the winter. The roots are the most vulnerable part of any plant. They are protected planted in the garden but in a pot the roots are subjected to the cold and probably won't make it through the winter. Mulching over the roots (careful not to bury the crown) helps keep soil moist and cool during hot weather, protects plants during the winter and keeps fruit and flowers off soil where fungus spores would infect your fruit.
