Generally speaking, clematis vines prefer good, well-drained soil in a sunny to partly sunny spot. Their roots need to be cool so plant vines in such a way that the roots can be shaded. While most clematis are hardy in our area (we are Zone 6), C. armandii and C. cirrhosa var. balearica are not. They are the evergreen types and are Zones 8 and 7 respectively.
For more details on clematis, refer to ’The Concise Guide to Clematis in North America’ (2001) by Clearview Horticultural Products Inc. (just like we do!).
When to Plant
In our area, clematis can be planted any time the ground is workable. Clematis actually grow in a similar fashion to bulbs. They grow roots actively in summer and fall and store up energy for spring growth. In spring, they will produce 2-3’ of growth without any noticeable root activity.
Spring or Summer: If planting during this time, it is useful to periodically pinch out the growing tips. Remember to water throughout the season, especially during the heat of summer!
Fall: This is an ideal time to plant clematis. Prune the following spring no matter what pruning group your clematis belongs to. This may mean fewer blooms the first year but it will encourage strong root development and a more bushy plant.
Where to Plant
Though clematis prefer four or more hours of good sunlight every day, they will grow in most locations, including a bright north wall. Roots need to be shaded so select a location with a low growing shrub in front (or plant one at the same time). Factors to consider for specific locations:
Planting on a Fence or Trellis
If planting against a wall, your trellis should be constructed in such a way that it can be taken down in one piece when you want to paint your house. While sweet pea netting and plastic mesh work, wooden or metal frames are longer lasting and more decorative.
Planting in a Container
The minimum size of container must be 18” high, wide and deep. Avoid containers made of any material that will conduct heat, like metal. Ensure the container has drainage holes. Should your container be large enough, plant annuals or perennials around the base.
Ensure soil has good drainage; peat moss and/or bark mulch should make up to 50% of the composition. You will need to ensure the vines have proper support, even if it’s a tripod of bamboo canes or cedar stakes. When planting, the rootball should go in the center of the container.
Planting Through a Large Tree
Clematis are not heavy, strangling vines. They grow through their host trees doing very little damage. The exception would be some of the more vigorous species such as C. montana, which would require a large tree.
Try to position the planting hole in such a way that the vine will grow along the tree’s dripline
Follow the steps below for planting, but note that you angle your support stake from the planting hole to the trunk of the tree. Wrap the ‘connecting’ spot on the trunk with sweet pea netting or mesh to give the clematis something to climb on. It will find its way up after that!
How to Plant
Clematis want good, moist but well-drained soil, shaded roots, lots of room for the roots to grow, regular watering and feeding. Here’s a quick step-by-step to get you going:
- Ensure your clematis is well-watered before you take it out of the pot
- Dig a hole 18” high, wide and deep
- Cover the bottom of the hole with about 6” of good quality compost or well-rotted manure and sprinkle a hand-full of bone meal over top
- Add good quality, well-drained soil to cover the organic matter, and enough so that the rootball and 6 inches of the stem will be below the soil line
- Look for a staple at the base of the support stake and carefully remove it before manipulating the rootball
- Massage the pot so that the rootball will come out easily
- Set the clematis in the hole so that about 6″ of the stem is below the soil line (yes, this is important)
- The stem needs to be carefully but securely attached to a support so that damage to the stem does not occur. You can keep the stake that it came on with it. Attach this to your long-term support so that the stems are nice and straight.
- Backfill with good quality soil and another hand-full of bonemeal. Should you have clay soil, mix in up to 50% fir or hemlock bark mulch or peat moss so that your soil has great drainage. Should you have acid soil, add a little lime.
- Water in thoroughly
What to Plant
As there are so many incredible varieties to choose from, this is definitely the hardest part! In a nutshell though, if you’re looking for ‘best bets’, here are our suggestions:
Best Bets for Fragrance
- Many species are scented, though not highly fragrant. C. armandii is the most highly scented, while ‘Fair Rosamund’ is a fragrant large blooming type. Sweet autumn clematis and ‘Sweet Summer Love’ by Proven Winners are nice options too.
Best Bets for Fences
- Hands-down, C. montana types
Best Bets for Containers
- ‘Bijou’ is a newer arrival, and only grows up to 3’, but there are lots of varieties that only grow to 4-6’.
Best Bets for Year-Round Interest
- Evergreen clematis (C. armandii and C. cirrhosa var. balearica) are beautiful but do require protection in winter as they are not hardy in our area.
- C. tangutica are the most common of the yellow-flowered species and they produce interesting seed heads which remain on the vines most of winter.
Best Bets for Shadier Spots
- There are many varieties that are happier in more shady spots, but C. alpina, C. macroptela, C. montana and Jackmanii types are good choices.
As a rule of thumb, start feeding in early spring as soon as new shoots begin to grow, and continue feeding until the buds are well formed. Discontinue feeding until your clematis has finished flowering. All feeding should stop in mid-August. We recommend feeding with 10-15-19, or 14-14-14 in spring, to feed all summer.
Clematis pruning can at first seem daunting to folks but it really is very straightforward, and will improve the shape and condition of your vines. Timing is the key, and it depends on the flowering group of your vine (identified on the information tag, or just watch and see when it blooms).
- Flower only on growth produced the previous year. Pruning should consist of cutting out weak or dead stems as soon as they are finished blooming in May or June. Pruning later than June or very severe pruning will result in fewer blooms the following spring. The very popular C. montana and macropetala varieties fall into this group and, even though they will survive in our colder climates, if the tops are nipped off by extreme frosts, blooms that should have occurred in early spring might occur in the fall, if at all.
- Flower on wood that has been hardened by the previous season’s growth. Normal blooming patterns for this group consist of a heavy flush of flowers in May – June on the previous season’s growth followed by a second smaller flush of blooms in September on the current season’s growth.
- Bloom simultaneously on last year’s growth and the current season’s growth. Group B2 varieties normally bloom from June to September continuously. For pruning purposes these varieties can be treated either as Group B1 or Group C. If planted alone a Group C pruning regime every second year is recommended.
- For both Groups B1 and B2, in late February or March a light pruning with some variation in the length of the stems will help produce a well balanced Group B plant. Any weak or dead wood should be removed at this time and a careful spacing of the remaining stems is all that is required. The spacing of the stems will allow room for next spring’s mass of blooms to open pleasingly. A severe pruning will reduce the number of blooms at the plant’s next flowering, but will not hurt the plant; in many cases it will help produce a better balanced plant. If your Group B clematis has been neglected for many years, it can be rejuvenated by severely cutting back most of the old growth.
- Bloom only on the current year’s growth. Blooms commence in early summer and continue through to fall. Plants should be cut back in late February or March to two strong sets of buds on each stem as close to ground level as possible. The majority of the group C clematis start their new growth very close to where last season’s growth ended; so if left un-pruned they will very quickly grow out of control! Keep in mind that Group C clematis bloom on the current season’s growth, so if you don’t prune at all, the blooms will be at the top of the plant and a bare stem will gradually appear over a few years.
DID YOU KNOW… Clematis make lovely cut flowers! Blooms can last anywhere from 5-10 days. Pick them as they are just starting to open and keep them in a cool room to improve longevity. Fluffy seed heads make interesting late season cuts as well.