A bit unclear.. you covered the bare soil between the rows of plants with straw right? Don't cover the new plants, just snug the fresh mulch up close to them. All you have to do now is keep the soil moist and watch them grow. You may be better off putting your leaves and clippings into your compost pile since it will take some time for them to decompose enough to be of any use to the strawberries. The aged horse manure worked into the soil before planting will probably give them enough nourishment for this year.