Frost Effect on Peonies


Peonies (Paeonia spp.) thrive in colder winters since this is when they enter their period of yearly rest known as dormancy. Peony buds, on the other hand, may be frozen by the chilly temperatures if they awaken in the spring and are then subjected to a late frost shortly before they blossom. If there is a possibility of frost, peonies should be covered with a light cover. However, in regions with moderate winters when it is unusual to have consecutive days with temperatures of 45 degrees Fahrenheit or below, a lack of chilling period is more likely than spring frost to prevent flowers from blossoming.

Types of Peonies

There are three types of peony species: those that grow as trees, those that grow as herbaceous plants, and those that are intersectional, meaning they are a hybrid of tree and herbaceous species. Peonies that grow on trees have leaves that fall off in the winter, but their woody stems allow them to survive the season’s last frost. Peonies that grow from herbaceous perennials die completely down to the ground in the late autumn. Combining the large flowers of tree species with the delicate stems and leaves of herbaceous perennials, intersectionals are sometimes known as Itoh peonies. Intersectionals grow at a lesser height than tree species.

When in their latent state, certain intersectional peonies have stems that are an inch or two long and made of wood. These stems remain near the ground line. According to PennState Extension, the mature heights of peonies vary according on the type: tree peonies may grow up to 7 feet in height, herbaceous kinds can reach up to 2 feet, and intersectional peonies can grow up to 2.5 feet in height. You may buy peonies from your neighbourhood nursery or gardening shop, or you can acquire bare-root peonies from trustworthy internet sources and have them sent to you.

Peonies’ Season for Blooming

Tree peony and some early-blooming herbaceous and intersectional varieties are able to adapt well to moderate regions where they bloom from the end of April to the beginning of June. This is despite the fact that all peonies like extended, icy periods of winter cold. ‘Festiva Maxima’ is a herbaceous early blooming that is creamy white with touches of pink, while ‘Sarah Bernhardt’ is a rose herbaceous early bloomer. ‘Bartzella,’ a lemony yellow intersectional, will also lie dormant in areas where winter days seldom go as cold as 0 degrees Celsius.

The majority of peony need prolonged exposure to winter cold, which is characterised by periods in which temperatures vary from below freezing to no more than 45 degrees Fahrenheit. For the majority of peony, a minimum of 480 hours of chilling is required for adequate dormancy.

The herbaceous species of peony need the greatest number of hours spent in colder temperatures than the other two types. If herbaceous plants are planted no deeper than one inch below the surface of the soil, they have a greater chance of becoming dormant in regions with warm weather. Trees and other species that interact with them need to be planted at a considerably denser density.

Frost Protection and Frost Clean-up

It is feasible to provide a single peony plant with speedy protection from the spring frost by placing an upside-down rubbish can made of plastic over the plant. A translucent plastic drop cloth or row-cover fabric, such as agricultural fleece, may prove to be the superior solution when it comes to covering many peony at once. The cover may be supported by posts in order to prevent the plants from being damaged. Bricks or rocks may serve as an effective anchor for the cover’s four corners. A lightweight cloth that shields plants from the cold while yet enabling sunshine and moisture to reach the plant’s roots is called agricultural fleece.

After the first frost in the fall or the beginning of winter, it is vital to prune tree peonies by removing the leaves as well as any sick or damaged wood. Additionally, this is the time of year when the leaves of herbaceous and intersectional peony begin to wither and fall off. Because the fungal disease Botrytis blight overwinters in dead leaves, it is vital to remove the ground surrounding all peonies of any plant litter. This is required in order to prevent the illness. According to the University of Connecticut Home & Garden Education Center, removing mulch is also a good idea once the plants have been established. Fungus may hide in mulch, so this is another place where it may be hiding.