Dan West Garden Center
October 2008 Newsletter©
True Boxwood…
This is not boxwood. It is a Japanese holly.
This is boxwood.
So what’s the difference? Japanese hollies like sun and a soil pH around 5 to 5.5, are rapid growing and fairly inexpensive. Boxwood, for the most part, like shade, a pH around 6.5, are slow growing and are a little pricey because they grow slow. (There are a few exceptions which we’ll get into later.)
Proper placement is critical for boxwood. Avoid locations where the plant will be exposed to afternoon or early morning sun. Winter sun causes the foliage to bronze on many boxwood varieties. Summer sun can scorch the leaves. (By the way, they’re deer resistant!)
Winter sun also causes bark splitting which we have seen the last two years on many plants. Early morning sun on a cold stem causes rapid expansion of the tissue on one side, resulting in cracks. The same can happen with a rapid freeze following a warm day. Plants that have been fertilized late in the growing season are especially vulnerable with an early fall freeze, so don’t fertilize between July 1st and October 15th. A fall application of Milorganite or Plant-tone after October 15th (or when the night temperatures are falling into the 50’s) is very beneficial to boxwood. Re-apply in late March.
Boxwood like the shade of the north side of a house, but perform even better under the shade of a tree. Even in the winter, the tree limbs and trunk provide some shade. Boxwood probably also benefit from the competition of the tree. Boxwood like well drained soil, so in our heavy clay, the tree helps remove much of the water.
Here are some of the varieties you are likely to find in the Mid-South:
Buxus sempervirens – This is the common American boxwood and the most often used. Although slow growing, it is one of the fastest growing boxwood…a couple of inches a year to 15’ and occasionally larger. You’ll see this one often sheared and maintained much smaller, but if allowed to grow naturally, it is a large and somewhat open, globe shaped shrub. It is also the most susceptible to root rot, so plant it in a well drained area. It will lightly bronze if exposed to winter sun. (FYI: We’ve got some beautiful sheared specimens up to 40” tall. These are slightly taller than wide. Plus we have ‘estate” cut boxwood to 32”. These are sheared to be as wide as they are tall.)
Buxus sempervirens elegantissima - An attractive, somewhat columnar variegated variety. The dark green leaves are edged in a creamy yellow. Slow growing to 10’ or so and 6’ wide. This one needs to be in the shade.
Buxus sempervirens suffruticosa - This is the English boxwood. It is considered a dwarf, but it can grow to 4’ or more at a rate of about 1” per year. This is the one you see sheared as edging boxwood in formal English gardens. In my 35 plus years in this business, I have seen this plant die often. It is susceptible to boxwood decline (discussed later).
Buxus sempervirens ‘Graham Blandy’ - This is a cigar shaped cultivar to 12’ or so. Unfortunately it tends to open up with age, performs poorly in our soil and often succumbs to root rot. That said, I have seen some large specimens through the years in well maintained gardens.
Buxus sempervirens ‘Varder Valley’ - Forms a spreading flat topped mound about 3’ tall and 4’ wide. One of the best small boxwood for well drained areas.
Buxus macrophylla asiaticum ‘Greggem’ – Baby Gem boxwood. A very small, very hardy compact cultivar to 18” or so. Dark green foliage and good winter color.
Buxus microphylla - Littleleaf boxwood – There are several B. microphylla cultivars available.
B. microphylla var. japonica is the Japanese boxwood. Fast growing and much cheaper than most. It will grow in full sun but does take on a bronzed winter appearance. It’s light green in color and matures to 6’ or so. It takes shearing well, but should not be hard pruned.
B. microphylla var. japonica ‘Green Beauty’ - This one has excellent dark green color and performs well in the sun. Another good substitute for English boxwood. Good container plant, very tolerant of heat and drought. Matures to 3’ tall and 5’ wide.
B. microphylla var. koreana - Korean boxwood. This one tends to be more open and airy, so it requires more trimming if you want it compact. It is extremely cold hardy but does take on a bronzed winter color. Matures to 4’ tall and 6’ wide.
B. microphylla var. koreana ‘Green Gem’ - A dwarf Korean boxwood that retains good winter color. Matures to 2’ tall by 2’ wide.
B. microphylla var. koreana ‘Winter Gem’ - Another dwarf Korean with good winter color that is a little taller than wide. Grows to 4’ tall and 2-3’ wide.
B. microphylla var. ‘John Baldwin’ - An upright, slow growing cultivar. It has a slight bluish cast to the foliage and grows to 4’ tall and 2’ wide.
B. microphylla var. ‘Julia-Jane’ - Another upright grower that is great for pyramidal trimming. It has dark green foliage, new growth is lime green and it matures to 5’ tall and 3-4’ wide.
B. microphylla var. ‘Morris Midget’ - A compact cultivar to 2’ tall and a little wider. It is very slow growing, only about 1” or less a year. This is a better choice than the English boxwood for our area. It is more tolerant of heavy clay soils.
Buxus sinica var. insularis ‘Justin Browers’ - This is an even better option than English boxwood. It is more tolerant of sun and heavy clay. It matures to 2 feet tall and 3 feet wide, also at the blazing growth rate of about 1” per year.
Buxus sinica var. insularis ‘Wintergreen’ - This is a fast growing inexpensive boxwood that makes an excellent replacement for Japanese hollies if yours are dying from black root rot. Tolerates sun and shade, has good winter color and shears easily. Matures to 4’ tall and about 6’ wide.
Buxus x Glencoe (Chicagoland Green) - One of the best at retaining it’s green color through the winter. Matures at 4’ tall by 5’ wide. Nice oval growth habit.
Buxus x ‘Green Mound’ - A dwarf cultivar to 3’ tall and wide. Good dark green color, requires little pruning.
Buxus x ‘Green Mountain’ - A conical cultivar than matures to 5’ tall and 3’ wide. This one does not bronze in the winter. It retains a dark green color and is a great container plant.
Buxus x ‘Green Velvet’ - A globe shaped cultivar maturing to 3’ tall and wide. Good green color with minimal winter bronzing. Tolerates sun well if not allowed to become too dry.
Buxus harlandii – Often called a Korean boxwood, it’s really a Chinese boxwood, native to Taiwan. It has a unique leaf; the tip is indented instead of pointed (far right picture above). It has bright green foliage and tolerates sun to partial shade. It has better drought tolerance and pest resistance than most boxwood, but this is as far north as it grows. It grows slow and makes a beautiful rounded shrub if sheared. Left to its natural growth, it is wider at the top than bottom. It can grow to 6’ tall and wide, but 4’ is more common.
Boxwood is occasionally attacked by psyllids, leaf miners and mites. All of which are easily controlled. Root rot can be a problem in poorly drained soil and then there is… “Decline”.
English boxwood decline or dieback attacks only the English boxwood. There are at least 4 pathogens that have been associated with the condition but incorrect sun, low pH, poorly drained soil, cold damage, nematodes, drought, leaf buildup in the plant center or other improper cultural practices seem to bring on the decline. Plants die slowly and appear to be weak with scattered branches dying. Leaves drop prematurely and retained foliage has a yellow appearance. There is no cure. Remove infected plants and do not replant English boxwoods…they will die.
Stem blight attacks English and American boxwood. The fungus causes cankers on the stem and is usually associated with winter damage. The foliage thins and turns orange or bronze resembling winter damage. The difference is obvious in the spring. If it’s just winter damage, you’ll get a flush of healthy new foliage. If not…then cut out infected stems back to green tissue. A copper fungicide or lime sulfur may help prevent the condition.
Many of the new cultivars are very compact and need little if any trimming. American boxwood must be sheared to keep them thick or they will return to their natural growth and be open and airy. Dead or dying wood and tip trimming can be done at any time; major pruning should be done in early spring and not after June 1st. They are slow to recover from hard pruning so don’t, unless you must. Better to remove and replace if size is a concern.
To grow healthy boxwood, make sure you put “the right boxwood in the right place”, don’t let leaves accumulate inside the plant, don’t over mulch, keep the pH at 6.5, don’t over or under water and fertilize at the correct time. Sound picky, don’t they? Well the advice above is the exact same advice I’d give you for any plant…right plant-right place, keep leaves out of the center, mulch correctly, proper pH, water and fertilize properly.
Just a couple of reminders for October…
Now is the time to apply pre-emerge on your lawn unless you are seeding fescue.
It’s time to seed and fertilize fescue lawns.
Apply Milorganite to Bermuda and Zoysia lawns. A fall application of fertilizer improves the health of the turf, keeps it greener 2 weeks longer in the fall and greens it up 2 weeks earlier in the spring.
Buy your fall bulbs now and store them in your refrigerator until planting time after Thanksgiving. You’ll get larger flowers and more uniform stem length if you’ll start chilling now. Do not store any apples or pears in the same refrigerator. Ethylene gas released from the ripening fruit will destroy your flowers.
Your annuals are still pretty, but it’s time to plant pansies.
If you put your houseplants outside for the summer, move them into a little shade to help them acclimate for the move in. It’s also a good time to treat your houseplants with Bonide Systemic Houseplant Granules to kill any insects on the plants.
Last month’s mystery plant was Aspidistra elatior or cast iron plant. It is a great evergreen shade perennial and a super low light houseplant. My grandmother had one in her dining room for years. We had a number of correct guesses and, for the first time since we started this game, there were more correct than incorrect guesses.
Here’s this month’s mystery plant below…and I’m giving you 2 pictures!
The contest ends on October 15th. Drop by either store to enter or you can email your entry to questions@danwestonline.com. One winner, selected from all correct entries, will receive a $25 Dan West Gift Certificate.
Thanks again, for shopping with us at Dan West! We really appreciate your business!