BELMONT, N.Y. — Not long ago I was asked how I grow Clematis. A lady stopped at my garden and admired my several varieties of Clematis then asked why she could not grow this vine. I had to do a little research to answer her question, since I planted them and they grew without any problem.
My Clematis grow in a sunny location, since I have no shade in my yard, but these vines can be planted in a shady location and will add much needed color to an otherwise drab section of the garden – but to grow well they need at least 6 hours of sunlight each day. One thing to remember is that they like cool, moist, well-drained soil no matter where they are planted. They like to have their “heads in the sun and feet in the shade”. You can make sure their “feet” or roots stay cool and moist by using mulch or compost. Shade on the root area can be achieved with some companion plants such as hostas if you plant in the shade, daisies if you plant in the sun or even a rock. They will need plenty of water in the first season while the roots are growing and can also benefit from some 5-10-10 fertilizer.
Pink Clematis – Killian Donahue. (Photo: Colleen Cavagna)When purchasing your plants, check the hang tag on the plant or the notation in the garden catalog if ordering online. You want to be sure the plant will grow in your zone. Here, we are in zone 4, 5a or 5B depending upon your location and microclimate. I REALLY want a Pink Vanilla clematis which has small light pink flowers and smells like vanilla. It is just gorgeous BUT it grows in zone 6! Should I get it, mulch well in fall and hope it will survive? Probably not. I have done this before and have not had luck with plants surviving that are not suited for my zone. Be sure to save the hang tag or nursery description for future information.
The tag should list the zone, it will say something like “Z 5-7 or Z 3-5” depending on the variety of course. If it says Z 5-7, this tells you the plant will do well in zones 5-7. Eight is too warm and 4 too cold. You might get away with it if there is a very mild winter but odds are the plant will not survive outside the given zones. The description will also tell you if the plant needs, full sun, shade or part shade, how wide and tall it is expected to grow, staking needs, and sometimes what pollinators the plant will attract and/or possible deer resistance.
Clematis come in many different shapes and colors, pink, blue, red, white, yellow, purple etc. Rooguchi has purple bell like flowers with a lavender inside; Sweet Autumn clematis and Virgins Bower have dime sized flowers with 4 white petals converging on a fuzzy white and yellow center; Princess Diana is pink with bell shaped flowers. Niobe is dark red with 5 large petals. Some are single and others like Magic Fountains (blue), Avant Guard (dark red and pink), and Duchess of Edinburgh (white) have multiple rows of petals. Nelly Mosher (pink and mauve) and Jackmanii (purple), are good choices for first timers and are readily available with stunning single flat flowers.
These are viney plants that will grow 4-12 feet tall and sometimes up to 20 feet tall depending upon which variety you choose. This means you either have to train them along the ground as a groundcover or on a fence or trellis. You can also us fishing line or netting which will be virtually invisible when the plant grows over it. They also can be trained to climb up a tree. Clematis can reach 3-4 feet wide so you will need to consider this when planting in an established garden. Several of my clematis are trained along a fence and the rest to trellises. I secure the stems as needed with green wire. You can also use twine. In our area, Clematis bloom spring and summer with the exception of Sweet Autumn clematis which blooms late summer into fall. My Sweet Autumn clematis grows to the top of the first floor windows as does Rooguchi.
Once you have chosen your variety of clematis, put the trellis or support in at the time you plant the vine. This makes it easier to train the vines where you want them to go right away and you won’t damage the roots by putting the trellis in after the plant is established. The clematis will sometimes grow quickly and if you miss a couple of days checking, you might have very long stems to wind around your support. You will also want to allow about a foot between a solid wall and the plant to allow for air circulation.
Dig a hole wide enough and deep enough to allow room for the roots and about 3” of soil on top of the roots. Cover the plant with soil then a couple of inches of mulch to protect the roots. Clematis do not mind sun but like their roots to be cool. Once planted, you will need to water the vine regularly especially in times of poor rainfall or drought. The first year your plant will be getting established and will not reward you with as many flowers as the photo on the hang tag or in the catalog. Not to worry it will improve in subsequent years.
Clematis can also be planted in containers. Select compact slow growing plants. Plants growing up to 8 feet will survive in containers such as Alaina, Crystal Fountain or Giselle Chose a pot 18” deep and 18” wide with drainage holes. Terracotta and ceramic pots cannot stand freezing temperatures without cracking. Resin pots do not provide sufficient insulation to protect roots from summer heat or winter cold. Plastic or cement will work well. Place a layer of coarse gravel or pebbles in the bottom of the pot to provide drainage. Add a layer of compost or organic matter to the pot and fill with loam based potting soil. If your plant is bare root, soak in water for 10 to 20 minutes before planting. Place the vine in the pot with soil supporting the stem of plant. Watch and water as needed. Your plant will need more water on a hot day than on a cooler day. For winter, you can either bring the pot into a garage, breezeway or house. It could stay out if you place the pot against a wall and wrap the container in bubble wrap or straw to prevent freezing. Each year replace the top 2-3 inches of soil and add compost each spring.
As fall approaches you might start wanting to cut back the plant and dead looking stalks. BUT, before you pick up your clippers, check the hang tag or nursery description for your plant.
Clematis are divided into three categories for pruning and using the incorrect method could cost you your flowers the next year.
Group 1 or A: (Atragene) The plant flowers early April/May on shoots produced the previous summer and needs no pruning except removing spent flower heads. Pruning this type will result in loss of the flowers the following year. You may need to periodically prune to remove any dead stems.
Group 2 or B: These bloom on both old and new growth in mid-late May and may bloom again in September. Prune in the spring when the buds swell or after the first flush of flowers in spring if the vine needs to be shaped or its growth controlled.
Group 3 or C: (Viticelli) Bloom on current season’s growth late in the season. This group needs hard pruning. Cut back in the spring to a pair of strong healthy buds at the base of the plant or about a foot to a foot and a half from the base of the plant. I leave two of mine to do in early spring as the birds seem to find shelter from wind in the ones I have. If you don’t do a hard prune on this group, your plant will begin to only have flowers way at the top, leaving a scraggly looking base and middle.
No matter what the size of your garden, you can find a clematis that is perfect for you. Consider giving this wonderful plant a place in your garden this year or next.
–Pam Jones, Master Gardener Volunteer
Cornell Cooperative Extension of Allegany County
For more articles out of New York, click here.