Gadenin日本語Get the appBury the crown three to four inches deeper than it grew in the pot
Almost every planting guide tells you to set a plant at the same depth it grew in its container. Clematis is the exception, and the reason is clematis wilt. The fungus enters through a wound or a weak point low on a stem and kills everything above it. If the crown is buried, there are dormant buds sitting below soil level that the fungus never reaches, and the plant regrows from them after you cut the dead stem away. A crown planted at pot level has no such reserve, and one attack of wilt can be the end of the whole plant.
Set the top of the rootball three to four inches (8 to 10 cm) below the finished soil surface. Dig the hole about eighteen inches (45 cm) across and deep enough that the rootball sits that far down with room for loose soil underneath. Backfill around the buried stems with ordinary garden soil mixed with compost. The buried section of stem does not rot; it thickens and produces roots and buds.
The large-flowered kinds benefit most from deep planting because they are the ones wilt attacks. The small-flowered species types are rarely troubled by wilt at all, but planting them deep costs nothing and steadies them in wind, so do it anyway rather than trying to remember which is which.
- Soak the plant before it leaves the pot Stand the pot in a bucket of water until the bubbles stop, usually twenty to thirty minutes. A dry rootball planted dry will shed water rather than absorb it, and clematis roots are slow to recover from that first check.
- Dig wide, not just deep Eighteen inches (45 cm) across and about the same deep. Fork the base of the hole so roots can go down. Mix a bucket of compost into the soil you took out, but do not fill the hole with pure compost, which sinks and leaves the crown exposed.
- Set the rootball low and backfill in stages Position the rootball so its surface is three to four inches (8 to 10 cm) below the surrounding soil. Backfill halfway, water to settle it, then finish. Firm gently with your hands rather than treading, which compacts soil around new roots.
- Lead the stems to their support Do not plant hard against a wall or a post. Set the plant twelve to eighteen inches (30 to 45 cm) out from the base of its support and lean a cane from the crown to the support so the stems have a route to travel.
- Water in deeply, then mulch Two full watering cans, poured slowly. Then mulch two to three inches (5 to 8 cm) deep over the whole root zone, keeping the mulch just clear of the emerging shoots themselves.
Cool roots, sunny top
Clematis grows in the wild with its roots in the cool leaf litter at the base of a hedge and its stems scrambling up into the light. Reproduce that split and the plant does most of the work itself. Ignore it, and you get a plant that flowers thinly and flags every hot afternoon even though the soil below is damp.
The stems want six hours of sun a day for the free-flowering kinds; a few of the vigorous small-flowered species will flower acceptably with less. The root zone wants shade for the hottest part of the day. You can create that shade with a paving slab laid over the roots, a deep mulch, or by planting a low shrub or a group of perennials on the sunny side of the crown. Any of the three works. What does not work is a bare, sun-baked strip of soil at the foot of a south-facing wall.
Wall plantings need one extra thought. The strip of ground within a foot of a house wall is the driest soil in any garden because the overhang keeps rain off it and the masonry pulls moisture out. Plant at least eighteen inches (45 cm) out from the wall and lead the stems back to it. A clematis planted tight against the brickwork will need watering every few days for its entire life.
| Position | Suits | What to fix |
|---|---|---|
| South or west wall, open ground | Large-flowered types | Shade the root zone; plant 18 in (45 cm) out from the wall |
| East-facing fence | Most types; morning sun suits pale flowers | Nothing. Pale flowers hold their color better here |
| North wall | Vigorous small-flowered species only | Do not expect heavy flowering from large-flowered kinds |
| Growing up through a shrub | Species types and hard-pruned kinds | Plant outside the shrub's root spread, lead stems in on a cane |
| Large container | Compact, hard-pruned types | Minimum 18 in (45 cm) deep pot; shade the pot itself from afternoon sun |
A clematis in a pot needs a bigger pot than people expect and a pot that does not cook. Terracotta and dark plastic in afternoon sun both raise the root temperature far past what the plant will tolerate. Stand the pot in shade and let the stems climb out into the light.
The first season: cut it back, however painful
A newly planted clematis usually arrives as two or three long stems tied to a cane, and it is very tempting to spread those out and leave them alone. Do not. Cut every stem back to about twelve inches (30 cm) above the ground in the first spring after planting, cutting just above a strong pair of buds. You lose that year's flowers on those stems and gain a plant with four or five shoots coming from low down instead of two bare whips with all the growth at the top.
This one cut is the difference between a climber clothed from the ground up and one that is bare for the first four feet for the rest of its life. Clematis does not readily produce new shoots from old bare wood, so a plant that starts leggy stays leggy. On a very vigorous plant a second hard cut the following spring is worth it too.
Water the first summer as if the plant were still in its pot. Once a week is not enough in hot weather; twice a week, given as a proper soak of a gallon or more, is the right rate until the plant has been through a full growing season. Do not feed heavily in the first few weeks. Let the roots go looking for what is already in the soil.
What to note down at planting
Write down the planting date, the position, and one thing most people never record: how deep you buried the crown. When wilt takes a stem three years later and you are deciding whether to cut below ground and wait for a regrowth, knowing there are buried buds down there changes the decision from a gamble into a plan.
Also record when the plant flowers in its first proper season, because that is what tells you its pruning group, and pruning group governs everything you do afterwards. A note that says the first flowers opened in mid spring on last year's stems, or in high summer on this year's growth, is worth more than any label that has faded or blown away.
Keep a note of where each crown sits, ideally measured from a fixed point such as a post or a corner. Hard-pruned clematis disappear completely in winter, and a fork through a dormant crown is a common and entirely avoidable way to lose a plant.