Tips For Fall Planting Perennials In Cold Winter Regions
Fall planting of cold-hardy perennials, shrubs and trees, has many advantages. Chief among them being that these fall transplants will be larger and display more flowers than the same size plant transplanted in the spring. Fall is a time for active root growth when weather temperatures are more moderate. Plants will be actively growing below ground even if you don't see much new growth above ground. And next year, when the summer heat arrives, they will be well established and ready for tough heat of summer weather.
Some Plants Are Especially Cold Hardy
Many cold hardy perennials, shrubs and trees are excellent candidates for fall planting. In general, plants with USDA cold hardiness ratings of 3, 4 and 5, are the best candidates for fall transplanting in cold winter climates.
If you're not an experienced fall planter, be conservative and select plants that are one zone more cold hardy than your area. You're in zone 5, choose zone 3 and 4 plants. Zone 6? Go with plants hardy in zones 3-5. With experience and practice, I'm confident that you'll do more of it in the future.
Fall is the Very Best Time to Plant in These Parts of the US
In regions like the Gulf Coast, the southern half of TX, southern CA and the desert Southwest that suffer very hot summers and yet enjoy mild winters, fall transplanting is absolutely the best time to plant. In fact, the planting season in zones 8-10 extends through winter as well. This will allow the plants to establish their roots before the extreme heat of summer and makes the plants much less vulnerable to drying out too quickly or heat exhaustion.
For these USDA zone 7-10 regions, you can plant any regionally suitable species in fall, with the exception of zone 3 and 4 plants. It's too hot for these cold lovers to do well long term.
The keys to successful fall planting cold-hardy perennial plants include:
- Roots need unfrozen soil to grow and prosper, so it's highly advisable to transplant 6 to 8 weeks before the first average date of hard frost. (This data is readily available from local weather websites.)
- For the USDA zone 3 areas of the country, Fall is not the time to plant. It's best to plant in mid- to late spring as the ground freezes too soon for good root growth before the onset of winter.
- Make a nice wide, deep water holding saucer (well) around the base of new transplants and fill it with a good quality, coarse-textured mulch (not whole leaves or grass clipping which can create a smothering mat of materials that prevent air and water exchange with the soil below).
- Mulch the planting bed around the new transplants as well. Mulching in the fall keeps the soil just a little bit warmer giving all the plants (new and established) extra time for fall root growth.
- Be sure to give fall transplants (as well as established plants in arid climates) a long, deep final watering after the first hard frost (25° F or lower) to thoroughly saturate the soil.
- Leave the plants standing; don't cut off the frost killed stems and leaves. Instead, let the entire plant remain in place and cut back come mid-spring. This is a proven technique to improve winter cold hardiness by allowing the plant to gradually re-absorb nutrients and minerals from the dying leaves and stems into the crown.
- Avoid transplanting plants that like fast draining soil in low spots that accumulate water from melting snow and early spring rains.
A List of Extra Cold Hardy Plants That Thrive With Fall Planting
- Achillea (Yarrow)
- Centranthus (Jupiter's Beard)
- Echinops (Globe Thistle)
- Hemerocallis (Daylilies)
- Iris (German Bearded Iris)
- Linum (Blue Flax)
- Monarda (Beebalm)
- Nepeta (Catmint)
- Papaver (Oriental Poppies) - 'Prince of Orange' has huge orange flowers with a black center. And remember, fall planted Oriental poppies are much more likely to bloom their first growing season than ones planted in spring.
- Penstemon (Beardtongue) - look for zone 3/4 cold hardy species
- Perovskia (Russian Sage)
- Phlox paniculata (Garden Phlox)
- Ratibida (Prairie Coneflower)
- Rudbeckia (Black Eyed Susan)
Spring Flowering (Fall-Planted) Bulbs
- Tulipa (tulips)
- Narcissus (daffodils)
- Muscari (Grape Hyacinth)
- miniature Iris
- Allium (ornamental onions)
Text and Photos by Founder and Chief Horticulturist David Salman.
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