Do strawberries grow slow?

More than a month ago I've transplanted two of my strawberry sprouts, unfortunately they died in watering, they're so fragile that a drop of water from fourty centimeters can break them.
After five to six weeks they have grown only twice the size in their plastic protection shield, I've transferred four of them to two bags filled with dirt.
Here's their current state for future reference:

Now I have this question, do strawberries grow then times slower than other plants or they're slow because I've planted them in the hot season?