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Q. Why won't some plants be available for
sale after this year? A. Several common landscape
plants have made it onto NH and Massachusettes Invasive Non-Native Species List. They are deemed to be invasive
due to their rapid growth and ease of propagation, which causes them to crowd out native plants. The best known example of
this is the purple loostrife. The Burning
Bush (Euonymus alatus), Japanese Barberry (Berberis thunbergii) and Norway Maple (Acer Platanoides)
are not legal for sale and were prohibited starting January 1, 2007. This includes the popular Crimson King Maple which
is actually a Norway Maple, not a Red Maple as many people think.
The following is the list of Currently Prohibited Plants in NH: Tree of Heaven (Ailanthus altissima)
Garlic Mustard (Alliaria petiolata) European
Barberry (Berberis vulgaris) Oriental Bittersweet (Celastrus
orbiculatus) Black Swallow-wort (Cynachum nigrum )
Pale Swallow-wort (Cynanchum rossicum) Autumn
Olive (Elaegnus umbellata) Giant Hogweed (Heracleum
mantegazzianum) Yellow-Flag Iris (Iris pseudacorus)
Blunt Leaved Privet (Ligustrum obtusifolium) Showy Bush Honeysuckle (Lonicera x bella) Japanese
Honeysuckle (Lonicera japonica) Morrow's Honeysuckle
(Lonicera morrowii) Tatarian Honeysuckle (Lonicera tatarica)
Japanese Knotweed (Polygonum cuspidatum) Common
Buckthorn (Rhamnus cathartica) Glossy Buckthorn (Rhamnus
frangula) Multiflora Rose (Rosa multiflora)
Fanwort (Cabomba caroliniana) Variable
milfoil (Myriophyllum heterophyllum) Purple loosetrife (Lythrum
salicaria) Common Reed (Phragmites australis)
Q. How do I plant my trees/shrubs?
A. First, you want to dig a hole twice as wide, but only as
deep as the pot/rootball. Add bonemeal or superphosophate to the bottom of the hole to promote root growth. Place the plant
as straight as possible in the hole and backfill just to the top of the rootball. Natural burlap and twine can be left on
the rootball, since it will rot. When in doubt, cut the twine and loosen the wrap after the plant is placed in the hole. Mix
the soil with compost. (if the soil is has clay, adding sand also will loosen it up). Top with mulch, but keep the mulch from
touching the bark of the tree, or it will create rot.
If your soil is very poor with heavy clay, you should raise the bed by at least 8 inches
with good topsoil to create decent drainage. While most plants like their water, very few will thrive in constantly saturated
soil, especially soil that is so heavy their roots will have difficulty spreading.
Q. How much and how
often should I water my transplants?
A. Probably more than you have been.
One of the biggest mistakes people make is insufficient watering of their new plants.
Most people think that because they have an irrigation system for their lawn that also sprays their plant beds, their trees
and shrubs are recieving enough water. Lawn watering systems are programed to run one to three times a day for a short period
of time, usually between 10 to 20 minutes. This soaks only the first few inches of soil, which is fine for lawns because
of their shallow root systems.
Trees and shrubs need to develop deep reaching roots to allow them to withstand drought,
extreme cold, and for trees, wind. Shallow watering encourages shallow weak roots. Trees and shrubs require slow, deep
watering, reaching down well past the bottom of the root ball. They do best on a drip irrigation system or soaker hose. If
that is not an option, place your hose at the base of the plant and turn on the water just enough to start it dripping, and
just leave it for several hours. Depending on how hot the weather is, and how much rain we've gotten, this may need
to be done as often as daily, or as little as twice a week.
Deep watering should continue until the plants go dormant in the fall. This will ensure
that they are adequately hydrated until spring.
A. Hydrangeas can fail to bloom for several reasons. First, location is important.
They need lots of water in hot weather, and rich soil. The site needs at least morning sun, and while some do well in
full sun, most do best with afternoon shade. Full shade is not appropriate for hydrangeas.
The second mistake most gardeners make with hydrangeas is improper pruning. There are many
divisions of hydrangeas, some bloom on new growth, others set their blooms on the previous years growth.
Hydrangea paniculata includes the 'Pee Gee (PG)' and 'Tardiva', and has a
pointed dome shaped bloom, mostly white. Hydrangea arborescens includes 'Annabelle' and has a broad white
dome of flowers. Both are fast growers and bloom on new wood, which means they can be pruned severely in the late winter or
early spring and then leave them alone.
Hydrangea quercifolia, also known as the Oakleaf Hydrangea has scalloped
leaves likes, full sun to light shade and is slower growing. Oakleafs bloom on OLD wood, and as such are best not
pruned. If pruning is absolutely needed, remove the entire stem in late winter to keep the best bloom potential.
Hydrangea macrophylla includes the mopheads and the lacecaps. Most
bloom on OLD wood, so minimal pruning should be practiced. There are now several varieties classified as rebloomers,
which mean they bloom on old and new growth, so they are generally more forgiving of mistakes. Varieties
include 'Penny Mac, 'Endless Summer', 'Dooley', 'David Ramesey'. What gardeners need to be cautious about is that not
all macrophyllas, including rebloomers are hardy up here in NH. Many macrophylla varieties
will die down to the ground during cold winters, and since there is no old wood for them to bloom on they won't flower,
or will flower poorly.
Hydrangea anomala s. petolaris, aka Climbing Hydrangea bloom on old wood,
so pruning a younger plant will eliminate flowers. However, older plants have many stems, so they are tolerant of some
shaping.
A. That pretty much depends on the plant. In any case, remove any dead or damaged branches in late
winter or early spring. Most shrubs which bloom on the current year's growth can be shaped at this time also. Spring
blooming shrubs such as rhododendrons should not be pruned until after they are done flowering or you will remove that year's
buds. The same applies to hydrangeas. Non blooming shrubs such as yews and boxwoods can be trimmed almost any time.
Often, some will not prune after August because they do not want to encourage new growth as winter approaches. Pruning should
be avoided during hot spells to lessen the stress on the plant. If you are removing diseased branches, sterilize your pruner
blades by dipping them into alcohol or a water/bleach mixture between cuts so the problem does not spread
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