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Clematis

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Clematis plants come in endless forms and colors: large, sturdy vines up to 30’ high or smaller vines, 6’ – 8’, suitable for containers; big, bold expansive or delicate bell-shaped flowers. Some varieties bloom in spring, some in summer or fall. For best results, purchase container-grown plants with multiple stems, healthy green growth, and a root system that fills the container.

Clematis Require:

  • 6 hours of full sun each day (generally)
  • cool, moist, shaded roots
  • well-drained, fertile soil
  • support - a trellis, arbor, post or fence
  • regular feeding and watering
  • some pruning at the right time, depending on the type (See chart)

How to Plant

  1. Test the pH level of the soil. Clematis prefer a pH of 6.5 - 7.0.
  2. Provide support for the vine at planting. This helps prevent injury to stems.
  3. Cut stems of the plant back to 12” to minimize breakage during planting and to encourage branching.
  4. Prepare a planting hole 2’ in diameter. Loosen all the soil within a 2’ diameter circle to a depth of 2’.
  5. Estimate the volume of soil in the planting hole. Substitute 1/3 of the volume with compost or well-rotted manure. DO NOT use fresh manure.
  6. Remove enough soil from the center of the hole to accommodate the plant’s root ball PLUS another 3” – 4” in depth.
  7. Set the plant in the hole so that the crown (where stems meet the roots) will be buried 3” – 4” below the surface of the soil.
  8. Fill in around the roots with amended soil. Tamp the soil firmly to eliminate air pockets.
  9. Apply 1 gallon of water when 2/3 of the soil is filled in. Continue to fill in to the soil line, then apply 2 more gallons of water.

Tips for Success

  • Fertilize clematis in April, June and August with a general purpose, balanced fertilizer.
  • Water once a week, deeply, during dry spells.
  • Underplant clematis with low-growing annuals, such as violas, or cover a 4’ – 6’ diameter area with mulch or flat stones to keep roots shaded and cool.
  • Keep mulch 8” away from the base of clematis stems to prevent stem wilt.
  • Protect the plant from mowers and trimmers. Install a barrier, such as hardware cloth, around the base of the plant, 8” away from stems.

Clematis Wilt Management

Prevent breakage and injury to stems. Look for blackened or wilted areas along the stems. Cut any affected stems back to the soil line. Healthy new stems will emerge from the crown. Dispose of diseased stems in a sealed plastic bag.

Clematis Types Bloom Time Flowering Characteristics Best Time to Prune

Group One

Early Flowering

April - May Flowers appear from buds produced the previous season. Examples: C. alpina, ‘Stolwijk Gold’, C. macropetala, C. armandii, C. montana In late June and July, immediately after flowering, prune lightly to control size and to remove broken, weak or dead stems. Prune annually, no later than the end of July.

Group Two

Large-flowered hybrids, often with two flushes of bloom

June - July Flowers appear first from buds produced the previous season and then on new growth. Examples: ‘Nelly Moser’, ‘Henryi” , ‘Niobe’, and many others! In February or March, remove dead and weak stems, then cut back remaining stems to the topmost pair of large, plump green buds – anywhere from a few inches or a few feet from the tip of the stem.

Group Three

Late-flowering

Mid-June through Fall Flowers appear on the last 2’ – 3’ of new growth in early summer to fall. Examples: C. florida ‘Plena’ and ‘Sieboldii’, C. x jackmanii ‘Superba, and‘ Comtesse de Bouchaud’ In early spring, after buds swell, cut each stem to a height of about 2’ - 3’. Leave at least two pairs of buds on each stem.

Resources

http://ag.umass.edu/resources/home-lawn-garden
http://www.mass.gov/agr/massgrown/
www.massflowergrowers.com

Last Updated: 
Apr 4, 2012
Topics: 
Home Lawn & Garden
Home Lawn and Garden topics: 
Flowers