Trees improve water quality by slowing and filtering rain water as well as protecting aquifers and watersheds.
Tree Pit Gardening
Image courtesy of Blue Tomato Design.
When a new, tree is planted in front of a home or business, 30 square feet of new planting space comes with it in the tree pit. Perennials, annuals and bulbs are beautiful additions to a tree pit, as long as you remember that the tree’s health comes first. Well maintained tree pit gardens enliven the public right of way along your block, throughout the neighborhood, and in business districts. (Disclaimer: the City of Pittsburgh requires an encroachment permit for anything planted or installed in the right-of-way. While this rule has not been enforced for gardens, Tree Pittsburgh wants you to be aware of it. Every tree planted in the right-of-way has an encroachment permit already.)
Tree pit gardens
- Can dissuade dog owners from letting dogs “use” the tree pit
- Remind the owner to water the plants and the tree that was recently planted
- Prevent cyclists from locking bikes to a newly planted tree
- Look great
Guidelines for Tree Pit Gardening:
- Do not plant vines or plants that will creep up the tree trunk or onto branches.
- Plant at least one foot away from the tree’s trunk so as not to disturb the roots there.
- Plant shallow rooted plants that won’t compete with the tree’s nutrients.
- Remember to water the tree pit enough so that both the plants and the tree get water!
Tree Pit Approved Plants
• Choose plants that require little watering. Key words to look for are “drought tolerant” and “xeric conditions”.
• Use small plants and bulbs – large plants require large planting holes, which damage tree roots. In addition plants with large root systems compete with the tree for water and nutrients.
• Do not add more soil to your tree pit. Raising the soil level will harm the tree. • Mulching a tree pit is always good for your tree and plants. Mulch keeps the soil moist and prevents weeds from sprouting in tree pits.
• NEVER PLANT! Bamboo, Ivy, Vines, Woody Shrubs, Evergreens or Invasives! They are all major competitors for water and nutrients and can stunt or kill a tree. See a list of invasives in Pennsylvania here.
Bulbs are a nice addition to tree pits, and neighborhoods often plant them in the fall during tree plantings. Many Bulbs will return each spring, bringing color to your neighborhood. They are both affordable and easy to plant.
Plants for the Sun, Good for newly planted trees
Annuals--plants that live only one year and need to planted annually:
- Sweet Alyssum (Mat forming, small yellow or white flowers)
- Dusty Miller – Senecio cinerara (Beautiful snow white and shiny silver color)
- Licorice Plant Helichrysum
- Portulaca-Rock Rose, Moss Rose (Good drought tolerant plant)
- Geranium (An old standby that requires little water)
- Scented Geranium (For leaf form, color and small flowers)
- Heliotrope (Beautiful scent)
- Cosmos (Dwarf – height 24”)
- Ageratum (Low growing with small purple flowers)
- Blue Marguerite Daisy
- Lantana (A variety of unique flowers)
- New Guinea Impatiens
Perennials (plants that live for more than one year):
- Ox-eye Daisy chrysanthnum leucanthemum (Beautiful white flowers)
- Bugleweed Ajuga reptans
- Snow in Summer Cerastium tomemtosum
- Lilyturf Liriope muscari
- Sedum Sedum albuonor acre (Only low growing)
- Thyme Thymus serpiphylluur or pseudolanugipsus (Mat forming varieties)
Plants for the Shade, Good for newly established trees
Annuals-plants that last one year and must be planted annually:
- Begonia (Elegant flowers that come in a large variety)
- Coleus (Variegated foliage, purple flowers)
- Lobelia (Small edging plant)
- Pansy (Some are winter hardy)
- Viola Torenia (Looks like a small pansy)
- Impatiens (Popular colorful flowers that will do well in your tree pit, sun or shade)
- Monkey Flower Mimulus (A variety of colorful flowers)
- Browallia (Fabulous blue color)
- Fuchsia (Variety of species, most annuals bear a red tubular flower)
Perennials-plants that come back year after year
- Elephant’s ears Bergenia cordifolia (Holds good winter color)
- Coral Bells Heuchera
- Spotted Deadnettle Lamium maculatum (Excellent groundcover)
- Lilyturf Liriope muscari(evergreen)
- Foam Flower Tiarella cordifolia(Vigorous groundcover with white upright flowers)