SF Tree Council offers the following suggestions for plants that like to live under trees.

Tree Pit Gardening
Plantings in your tree pit can be attractive and very beneficial to the
tree. The roots of small plants, such as annuals keep the soil cultivated
(loose). They are easy to plant and maintain and inexpensive to buy. They
deter litter and dog walking by showing that the tree is cared for. A
tree pit garden adds color and life to the streetscape. Wilted flowers
indicate when the tree pit is dry. Here are some ideas for your tree pit
garden:

SHADE-LOVING ANNUALS

Begonias in a well-tended pit with an excellent guard.
Plant annuals in your pit if you have a young tree less than six inches
in diameter. Their root system is small enoungh that they won't compete
with the tree for water. These live only one year, and therefore must be
replanted each spring.

Impatiens x wallerana, Impatiens. An everblooming shadelover with red,
pink, or white flowers. The 1-foot plants will wilt badly when dry. The
best strain is the Super Elfin Strain.
Begonia x semperflorens - Cultorum, Wax Begonia. Red, pink, or white
flowers. The 6- to 8-inch plants can grow in sun or shade and are quite
drought tolerant. Some kinds have bronze foliage.
Lobelia erinus, Dwarf Lobelia. This is a low 6-inch plant that is grown
for its intense true-blue flowers that bloom continously throughout the
season. It also comes in sky blue, reddish purple, and white, and some
have a white eye that allows them to be easily associated with other
white-flowering or foliage plants. 'Cambridge Blue' is the most common,
with gentian-blue flowers and bronze foliage on compact plants. The
cascading types are loose and open and look very nice when allowed to
ramble through other plants. Prefers a moist soil rich in humus.
Lobularia maritima, Sweet Alyssum. The longest blooming plant of all.
Low, broad spreading plants
A deep red coleus in an iron wicket protected pit.
with white (sometimes pale pink or violet) flowers. Occasionally refusing
to bloom during the hottest weather, 3-Inch plants flower almost
continuously from April to as late as December. Sun or shade.
Coleus Blumei, Coleus. The flowerless coleus has large leaves in bright
beautiful colors. It grows 12 to 18 inches tall. Coleus are available in
a broad array of rich vivid colors for outstanding and eye-catching
displays. Plants will tolerate sun, but produce best color in partial to
full shade. An excellent choice for flowerless ground cover in tree pits.


SUN-LOVING ANNUALS

Plant at the base of a street only for the first two seasons after
planting the tree, when there is still plenty of sun reaching the tree
pit.

Pelargonium x hortorum, Geranium. 1-foot plants with red, pink, or white
flowers. Remove spent flowers.
Salvia splendens, Scarlet Salvia. Red (sometimes purple) flower spikes on
12- to 15-inch plants. Remove spent flower heads. Tagetes spp., Marigold
. Long-flowering and easy, with yellow, orange, or white flowers on 8- to
15-inch plants.

SPRING-FLOWERING BULBS

Plant in the fall. In the spring, after the bulbs have flowered, do not
remove leaves until they turn yellow.

Crocus spp., Crocus. They bloom in yellow, purple, and white in March.
Plant corms 2-3 inches deep, 1-2 inches apart, in tight groups. Must be
lifted and divided every 3-4 years.
Chionodoxa luciliae, Glory-of-the-Snow. These are lesser known than
Crocus but are of an intense royal blue with a white eye, 3-4 inches
high. It self-sows and does not need to be lifted and divided. Excellent
with daffodils. Same planting directions as Crocus.
Endymion hispanicum, Spanish Bluebells. Blue, but also comes in a
pristine white and a very intense pink. One-foot spikes bloom in May. An
excellent performer. Plant in groups of 3-10, 4 inches deep, 3-4 inches
apart.
Narcissus spp., Daffodils and Narcissus . Everyone loves these, which may
cause a problem. Passerbys may pick the flowers when they bloom in April.
Plant 6 inches deep, 4-6 inches apart. Because their leaves stay green
until July, floop over and look unsightly, they may be treated as annuals
by pulling them out after flowering, discarding them, and replanting new
bulbs in the fall. Bulbs need to be lifted and divided every 3-4 years.
Scilla siberica, Siberian Squill. Deep blue flowers, but not as showy as
Glory-of-the-snow. Same planting directions as Crocus.
Tulipa spp., Tulips. Available in many flower forms and in most colors
execpt true blue and black. Prone to being picked. Plant 6 inches deep,
4-6 inches apart. Unless species tulips are planted, they often do not
flower well after the first year. In that case, it is best to treat them
like annuals, as with Narcissus.

PERENNIAL GROUNDCOVERS

These herbaceous plants live for many years. Plant only when street tree
is well established - at least 6 inches DBH. These plants will compete
for water with newly planted trees.

Hedera helix, English ivy. The old, reliable standby. Able to grow in sun
or shade, drought resistant, salt resistant; in other words, very tough.
The common variety is 'Thorndale', with deep green leaves, but there are
many kinds with different leaf shapes and white, yellow, or gray
variegation. This mat-forming evergreen vine can climb up a street tree,
but will not harm it.
Vinca minor, Periwinkle or Myrtle. A 4-inch tall nonclimbing vine with
small, oval glossy evergreen leaves with blue (or rarely white) flowers
in April.
Lamium maculatum , Dead Nettle. A low deciduous groundcover with grayish
white leaves. 'Beacon Silver' has pink flowers in May and June, 'White
Nancy' has white flowers. Lamiastrum galeobdolon is similar but much more
rampant.

SHADE-LOVING PERENNIALS

A lovely mix of flowering annuals and the taller, broad-leaved perennial
Hosta.
Alchemilla mollis, Lady's-Mantle. This 1-foot plant has pleated,
kidney-shaped leaves and long lasting chartreuse flowers similar to
Baby's-Breath. Takes dry shade well.
Brunnera macrophylla, Siberian Bugloss. This plant has bold foliage and
bright blue Forget-me-not like flowers and grows to a height of 1 foot.
Hosta spp., Plantain lily or Hosta. A durable, broadleaved plant with
weed-smothering bold leaves. There are white-, yellow-, and gray-leaved
forms. Flower stalks rise above the foliage in summer.
Phalaris arundinacea 'Picta', Variegated Ribbon Grass. An indestructible
white-variegated grass that is a rampant spreader. Sometimes turns brown
later in summer, but cut it back to the ground and it will sprout a fresh
batch of foliage.


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51 Chambers Street, Suite 1412A ~ New York, New York 10007
212 227-1887 phone ~ 212 732-5325 fax
treesny@treesny.com

-- carolyn c/o gary (gary@word.to), February 11, 2003