Fall preparation for herbaceous perennials

Preparing for winter in Vermont usually happens in the perennial garden in November after we have had a few hard frosts to slow or stop top growth. When this has occurred, you should begin cleaning out and cutting back non-woody perennials to the lower basal growth (usually you can see small leaves at the base of the plant). these leaves should be left alone so that you do not damage the crown by cutting too deeply.

Tips for specific popular plants

Although most perennials benefit from cutting back by removing the current season's growth, many need not be cut back except for maintaining shape. The following perennials benefit from cutting the top third of their height in late October or November.

These include:

Buddleia - Butterfly Bush - slow to break dormancy in spring

Cerastium - Snow in Summer

Clematis - Climbing vine - cut to maintain desired height. Some varieties may not bloom as well the following year, but the plant will thrive.

Dianthus - Pinks - remove messy foliage and seed heads

Lavendula - Lavender - slow to break dormancy in spring

Lonicera - Honeysuckle vine - cut to maintain desired height

Perovskia - Russian sage - slow to break dormancy in spring

Polygonum - Silver lace vine - cut to maintain desired height

Although this list does not include all plants which get one third cut back, it is a list of some of the more common ones you will encounter in our area. Please feel free to call if you need help with a specific plant.

Adding nutrients to your soil

In addition to cutting the perennials back and cleaning up the garden, now is also a good time to add a small amount of organic matter in the form of compost or peat moss. Just a small amount around each plant base about an inch deep will help replenish some of the nutrients used up the past season.

Division of perennials

Dividing perennials is a great way to add to your garden as well as rejuvenate them to produce stronger plants with more bloom the following year. With this in mind, you should also use the general rule of dividing spring and summer blooming perennials in the fall and fall blooming perennials in the spring. When dividing under these timelines you will cause a minimal negative effect on the following bloom cycle.

When dividing in the fall, you should do it early enough (mid September to mid October) to allow new roots to develop in the soil before the colder weather of late fall begins.

When dividing herbaceous perennials, prune the foliage back to 4-5 inches from the crown of the plant (just above ground level). This will allow you to divide more easily and allow the plant to produce roots rather than support top foliage. After cutting back you should dig up the entire plant to begin division. In many cases, you will be able to see that the more healthy-looking growth is on the edge of the clump rather than in the center. You can begin cutting out sections from this better looking area with a sharp knife or sharp spade. When doing so, make sure there are healthy roots and shoots in each section you plan on keeping and discard any that are not looking as well. Some perennials will seem to separate on their own and will not need this cutting but each plant will vary slightly from another. When you divide plants that are like this, you can pull them apart with your hands and then can replant each of the separations, also discarding any you do not wish to transplant.

If all goes well, we will have a mild winter with a lot of snow cover and the whole process can begin again next spring!

Claussen's Florist and Greenhouse
(800) 287-2361     (802) 878-2361
(802) 878-9462 (fax)
Chris Conant:

Claussen's Perennial Farm
(802) 879-6816
James MacAuley: