Thursday, April 27, 2023

Getting More Out of Your Ground Cover Plants

I have a very long strip of landscaping area between my lawn and the cul-de-sac, with six different types of plants growing (see photos below). I want to propagate those plants to make many more and fill in the area. In this article I will give the basic principles of propagation used for ground cover plants grown in this area.

Crown Division, or Division Division is form of plant propagation where new plants are not grown from seeds or bulbs but are separated from the parent plant. The crown of a plant is where its stem meets the roots.

  • Carefully lift plant clumps along with some soil removed from the roots.
  • The crown may then be cut into sections with a knife.
  • Individual growing points (shoots) that contain roots may be used to form new plants, or if a larger plant is desired, several shoots may be left together.
  • When dividing large, old crowns, it is often best to discard the older, center portions and replant the young, more vigorous shoots that have developed on the edges of the clump.                                                   
Stem Cuttings A stem cutting includes a piece of stem plus any attached leaves or buds, so it only needs to form new roots to become a plant.
  • Cuttings should be 4 to 6 inches in length and taken from vigorous, healthy plants.
  • Remove the cutting from the mother plant with a sharp, clean knife.
  • Use a rooting hormone.
  • Cuttings should be placed (stuck) in a propagation medium that retains moisture, yet is porous. Do not allow the medium to dry out.                          
Leaf cuttings
A leaf cutting uses just the leaf for propagation, so both new roots and new stems must be formed to create a new plant. Leaf cuttings first must form roots and later shoots. Depending upon the species, it can take several months to produce a plant suitable for transplanting from a leaf cutting.
  • Remove only a leaf blade or the blade and a portion of the petiole.
  • Apply rooting hormone, and sink the petiole into the rooting mix.
  • The base of the leaf blade should just touch the mix.
  • Place the pot in a plastic bag in a bright spot.
Root cuttings Though very few plants can be propagated from root cuttings, the technique is simple. 
  • When the plant is dormant, dig it up and cut off robust segments of the root, 2-3 inches long. 
  • If the roots are thin, lay them horizontally on the rooting mix and cover with 1/2 inch of the damp mix. If the roots are thick, lay them horizontally or place them vertically into the rooting mix, covering them completely. If placing the root vertically, make sure the end of the cutting that was nearest the crown of the plant points up. 
  • Put the pot in a plastic bag and place in a bright spot. In several weeks, shoots should emerge from the rooting mix. Keep the pot in the plastic bag until new roots have formed on the shoots.   

The chart below shows some of the common ground cover plants grown in the Treasure Valley of Idaho.

Common Name

Scientific Name

Best Ways to Propagate

Stonecrop

Sedum spurium 

Division 

Periwinkle

Vinca minor  

Division

Mazus

Mazus reptans

Rooting at the nods

Creeping thyme

Thymus serpyllum

Division, seeds or cuttings

White Woodruff

Golium odorstum

Self-seeds

Lamb’s Ear

Stachys bysantina

Self-seeds profusely

Houseleek / Hen & Chicks

Sempervivum tectorum

Leaf cuttings

Moss Phlox

Phlox subulata

Division, stem/root cuttings

Prickly Pear

Opuntia macrorhiza

Stem cuttings

Snow-in-Winter

Ceratium tomentosum

Self-seeding, division 

Rockcress 

Arabis caucasica

Seed, division/stem cutting

Candytuft

Iberis sempervirens

Division, or stem cuttings

Basket-of-gold

Aurinia saxatilis  

Self-seeds, or direct seeds

Bearberry Cotoneaster

Cotoneaster danneri 

Stem cuttings

Silver Mound

Artemisia schmidtana  

Division every 2-3 years 

Rose Moss / Purslane

Portulaca grandiflora

Cuttings

Ajuga  

Ajuga reptans

Seed or division