Made famous by the play A Scarlet Pimpernel, these low-growing plants are covered with dark red or blue flowers in the shape of a star. They are sometimes called the Poor Man's Weatherglass for their habit of closing their petals half an hour before rain falls. Pimpernel flowers are annual plants that fully lose their blooms during the winter. If planted in pots, bring inside to a heated room or covered porch for the winter months.
Spread compost. Before the first frost, mix compost into the soil of pimpernel to give them a quick boost of nutrients before the cold weather officially arrives.
Cut back any dead parts. After the first frost, pimpernel plants will not retain their blooms. Snip the stems and seed heads down to the lower ring of leaves called the "rosette."
Spread mulch. Add a 2- to 3-inch layer of mulch around the base of your pimpernel plants. This will help keep heat in the ground around the roots.
Remove dead leaves. In early spring, snip off any brown or yellow leaves on the rosette.
Cover with a breathable fabric. Place old bed sheets, towels and blankets on top of the plants, fully covering the base. Do not use plastic as this is not a breathable substance and will kill your plants. Clear off snowfall regularly.
Continue to water your plant. If you are not receiving 1 to 2 inches of rainfall a week, water your pimpernel plants once a week. Stick your finger a few inches into the dirt near the roots. If the soil is moist, the plants do not need watering. If the soil is dry, slowly soak the soil until the root base is fully wet.
Fertilize. As soon as spring arrives, spread an evenly balanced fertilizer on the soil of your pimpernel to encourage rapid growth. Hopefully the plants will have survived winter and will quickly put out new leaves and blooms.