The Spanish Lavender, or Lavandula Stoechas, is the most heat-tolerant lavender, growing 3 to 4 feet high and 3 feet wide. These mounding plants have blue-green foliage that complement their lavender-blue flower spikes that bloom in the late spring and summer. The flowers and foliage are fragrant. These plants accept some shade, and prefer it in the afternoon. The canopy coverage can be up to 7 square feet.