Nanking cherry and cross-pollination

I have had a Nanking cherry bush that I planted 3 years ago. The first year, as I expected, it didn’t produce flowers or fruit. The second year, it produced some flowers and about 4 small green cherries, which disappeared off from the bush in about a week. This year, it had a lot of flowers, but only produced 2 small green cherries, which also disappeared in about a week. I only have the one bush, and it seems very healthy otherwise. Is it due to being so young still? Do I need a second plant? Any advice would be greatly appreciated.

According to the Arbor Day Foundation, Nanking cherry (Prunus tomentosa) “is not self-fertile. Two or more shrubs should be planted within 100′ of each other to ensure cross-pollination.”

Information from Alberta, Canada’s Agriculture and Rural Development website (no longer available online) has some suggestions on cross-pollination:

“Nanking cherries need cross pollination, for fruit production, therefore more than one plant is required, or an early flowering plum such as Brookgold, Bounty or Dandy. Mature plants reach heights of up to 2 m. Plant in rows 3 m apart with 2 m between the plants in the row. Prune annually to prevent shrubs from becoming too dense. Remove no more than one-third of the total number of branches at one time. This allows the plant to replace older wood with young, vigorous wood.”

There is a chapter on Nanking cherry in Lee Reich’s Uncommon Fruits Worthy of Attention (Timber Press, 2004) in which he states clearly that cross-pollination is needed (some information on the web says that it is self-fruitful…which might be true to a small extent, but you will have a much better crop with cross-pollination). Some key points: Nanking cherry does well in sun and well-drained soil. Full sun is preferable, but it will still bear fruit in a shadier spot. It grows vigorously, and can live 50+ years. “Annual pruning, though not a necessity, brings out the best in any Nanking cherry in terms of yield and fruit quality. Prune in late winter with the aim of keeping a bush open so that all branches are bathed in sun and quickly dried by breezes. Accomplish these goals by shortening some branches, removing others entirely, and leaving still others untouched. This pruning will also stimulate a steady supply of young, fruitful branches each year.”

loss of fragrance in roses

I wonder why my roses have lost their fragrance. My ‘Double Delight’ roses used to have a good smell, and now the flowers are bigger and there is no fragrance.

It does seem mysterious that a once-fragrant rose should lose all fragrance. There are many factors which might cause the perceived lack of scent. According to The Graham Stuart Thomas Rose Book (Timber Press, 1994), rose scent itself is complex, and is composed mainly of geraniol along with many other substances. It is mainly released from tiny cells on the surface of the petals: “Scent is produced mainly in the petals and is given forth when the growth of the flower and the atmospheric conditions are right. From this it will be seen why double roses have more volume of scent than singles […] scent is especially apparent in most flowers when the air is neither too cold nor too hot […] In extreme conditions, such as wilting, extra scent may be released […] Usually the best fragrance is obtained from a newly opened flower growing on a healthy, well-established plant on a windless day when growth is exuberant […] we may expect fragrance to be at its best on a day when the air is warm and moist rather than dry, when the plant will be functioning well. It is not that moist air conveys better than dry, but that the plant is giving it forth in greatest quantity.”

From the above, you may want to consider the following

When you discovered the rose had no scent, were the atmospheric conditions optimal for the release of scent?
If scent is most prominent on healthy plants, are there any underlying reasons (pests, diseases, cultural problems such as overwatering, poor soil, etc.) the plant might not be at its strongest?

Other things to consider:
Environmental pollutants affect not only our sense of smell, but the fragrance emitted by flowers, as this 2008 University of Virginia study describes:
“‘The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today’s polluted environment downwind of major cities, they may travel only 200 to 300 meters,’ said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study. ‘This makes it increasingly difficult for pollinators to locate the flowers.’

The result, potentially, is a vicious cycle where pollinators struggle to find enough food to sustain their populations, and populations of flowering plants, in turn, do not get pollinated sufficiently to proliferate and diversify.”

Another thing that you might ask is whether your rose was grafted, and perhaps you are getting a different rose coming up from the graft. The loss of fragrance and the different appearance of the flowers makes me wonder if this could be what is happening.

pruning and maintaining ferns

I have questions on general maintenance for the ferns in my garden. It is winter and the wood ferns (now about 4 feet in diameter) have fronds which are now partially brown. The deer ferns look similarly forlorn.
Should I prune all the old fronds off and let the new ones take over? How and when to do this without damaging emerging new growth?

Sources are divided on when and whether to prune wood ferns (Dryopteris). Some consider Dryopteris “self-cleaning,” meaning that the old fronds will eventually disintegrate on their own (Gardening with Woodland Plants by Karan Junker; Timber Press, 2007). If you are inclined to tidy up the look of your plants, they can be pruned of their old fronds after new growth begins in the spring (this can be risky: be careful not to cut the new fronds), or according to Pacific Northwest sources, in late February or early March before new growth starts. Rainyside Gardeners and Great Plant Picks, two Pacific Northwest resources, offer more information. Rainyside advocates pruning once there is new growth, and Great Plant Picks advocates pruning before new growth begins. The same is true for deer fern (Blechnum spicant, now renamed Struthiopteris spicant): “Old fronds should be cut back in late winter or early spring before new growth starts.”

This is a good general guide for pruning maintenance of ferns, written by Richie Steffen of the Hardy Fern Foundation. The first thing he points out is that cutting back ferns is purely an aesthetic choice; it is not necessary. If you do want to cut back, consider the type of fern: is it evergreen, winter-green, deciduous, or semi-evergreen? The answer to this question will determine the best practice.

Chamaecyparis pisifera and flagging

Chamaecyparis pisifera ‘Boulevard’ is prone to foliage
browning towards the interior of the tree as it matures. What is the
cause of this and is there any remedy?

I consulted Pacific Northwest Landscape IPM Manual (WSU, 2002), which
mentions that lower branches tend to die in older Chamaecyparis pisifera.
This resource mentions cedar flagging as one of the cultural or
environmental problems which may affect this tree. It is normal for
evergreens to shed some old foliage every year, but this may be
intensified by stresses like drought, recent or poor planting, root
disturbance, or hot wind. Symptoms show up in the form of browned
foliage, usually most noticeable in the fall. The current year’s foliage
stays green at the tips. Remedies for excessive flagging would include
close attention to irrigation during periods of summer drought,
preventing root disturbance, make sure the tree was not planted too
deeply, and improve drainage if the soil tends to stay wet. (Replant onto
a berm or raised bed, for example).

Since the browning you have observed is on the interior, flagging would
be a likely possibility. Typically, the dead foliage gets blown out of
the plant and the plant returns to normal growth in the spring.
The following link, to a discussion on University of British Columbia’s
Botanical Garden Forums, may be of interest to you.

If you think something else might be going on, such as Phytophthora, you
might want to bring photos and samples to a Master Gardener Clinic for
diagnosis. Signs of Phytophthora begin at the small roots, progressing to
larger roots. The inner bark will show a brownish color. Eventually, the
foliage will turn color (yellowish to bronze and finally brown). This
doesn’t sound like your description, however.

Apricots and other stone fruits for the Seattle area

I would like to grow some fruit trees on my property; we have room for maybe 2-3 small trees. Do you have any recommendations for the Seattle area? I’m partial to stone fruits — although I had heard that apricots (Prunus armeniaca) don’t do well in Seattle.

I don’t think you need to give up on the idea of apricots, as there are a few varieties that will do well here, such as ‘Puget Gold’ and ‘Harglow.’ The book, Fruits & Berries of the Pacific Northwest, by David Flaherty and Sue Elen Harvey, also mentions ‘Jannes’ and ‘Tilton’ for Western Washington. The book, Pacific Northwest Guide to Home Gardening, by Ray McNeilan and Micheline Ronningen, lists ‘Jannes’ and ‘Tilton,’ as well as ‘Moorpack,’ ‘Perfection,’ ‘Riland,’ and ‘Royal.’ I would also recommend that you look at the catalogs of several Washington State nurseries that specialize in fruit: Raintree Nursery, Cloud Mountain Farm, and Burnt Ridge Nursery. Since you mentioned small trees, you would probably be looking for dwarf forms, depending on the space you have available. These should also be available from the nurseries listed above.

pruning Euonymus shrubs

Is it possible to arborize a large Euonymus shrub (by
selectively pruning many of its branches to create a tree shape), as one
can with rhododendrons? I prefer pruning over removal, if that option is
available to me. What tips can you offer for pruning Euonymus in this
way?

It is a little difficult to offer advice without knowing which species of
Euonymus you are growing. There are many, some evergreen and some
deciduous. The pruning method varies according to the species. See the
link here, from Oregon State University, for information on some of the
different species.

If you would like to get back to me with information about the species, I
will be better able to assist you. For now, here is general
pruning information and links which may be of use.

Seattle gardening expert Cass Turnbull and the organization Plant Amnesty
offer helpful pruning hints. Excerpt:

Punch List for Tree-Likes. Take out:

Dead wood

Suckers from trunk, roots, or branches

Crossing/rubbing branches (the worst ones)

Branches hanging on the ground

Wrong-way branches

Too-far-up/too-far-down branches

Parallel branches

Head back to shorten (if necessary) on shrubs, not trees.

Tree-likes vary in the degree to which they may be thinned before they
sucker back or suffer dieback. Removal ranges from approximately
one-eighth to one-third total leaf area.

Another excerpt, on arborizing shrubs:

Other people strip up all the lower limbs of shrubs they consider too
big, making them somewhat reminiscent of lollipops or ostriches. I
hesitate to mention stripping because of these common abuses. However,
there are some instances where removing the lower limbs of a shrub is a
good option. It will depend on the type of plant and its location. Don’t
strip up plants just because they seem too big. Good candidates are ones
that are actually impeding foot traffic or totally obscuring windows. The
best subjects are non-suckering tree-like shrubs. Usually they are
broad-leafed evergreens, such as rhododendrons, pieris, camellias, or
strawberry trees (Arbutus unedo). Stripping up works best on very old
shrubs. By cutting off the lower branches you are “arborizing” them.
“Arbor” means tree, and you are turning your big shrub into a small tree.
English laurel is a good subject. Instead of a giant oppressive blob, you
can have an open, sort of oriental-looking, small tree. In fact, one
could say that most of these plants are trees in their native habitats.
They start out as shrubs and grow into understory trees in their
adulthood. We just expect them to stay in the shrub-like juvenile stage
forever.

Some shrubs can be arborized, meaning that they can be pruned into small
trees.

Pause before you strip, though. It’s a major step. Look inside your shrub
and evaluate how the trunk will look when it’s exposed. Is it fat? Good!
Does it lean and curve gracefully? Great! If possible, endeavor to leave
some branches lower down and inside to avoid the stripped or gutted
appearance. To alleviate the lollipop effect, thin out the upper canopy
of leaves, too. It should look a bit lacy and like a tree, not like a
solid ball. Don’t arborize more than a few plants in your landscape, it
begins to look silly if you do too many.

Be sure to leave enough leaves to collect sunshine in order to feed the
plant. Shrubs and trees vary from species to species in the degree to
which they will let you put them on a diet. Trees and shrubs which have
been starved by over thinning usually succumb to death in a drought or
freeze. Be sure to help heavily thinned, non-suckering plants by
supplying sufficient water and fertilizer.

lilac and elm wood and allelopathy

I have a huge planter to fill but don’t want to buy that much soil so I want to partially fill it with wood. I’m going to plant herbs in it but I wanted to know if the wood I have would make eating the herbs inadvisable. I have roots and branches from a snake bark elm and some large pieces of lilac. None of the wood is treated but I know some wood is poisonous and wasn’t sure about these two.

Before you go ahead with using wood to fill in the planter, another trick
you might try is to put an upended smaller pot inside the large pot, if
the planter is too deep. What you are looking for is a potting medium
with good drainage.

I am not familiar with snakebark elm (there is a snakebark maple, and a
lacebark elm–might it be one of these?) so I can’t give a conclusive
answer about its wood or roots. The phenomenon of plants which are toxic
to other plants is called allelopathy. The most famously allelopathic
tree is the black walnut. Apparently, lilac wood (Syringa vulgaris) has
the ability to raise the phenolics content in the soil, according to a
2004 scientific article (now archived) I found, from the 2nd European Allelopathy Symposium.

To be on the safe side, I would avoid using the lilac and elm wood as
filler in your planter, since there are better options.

You may find the information below useful:

Local gardener Mary Preus’s book, The Northwest Herb Lover’s Handbook
(Sasquatch Books, 2000) offers a recipe for potting soil for herbs grown in containers:

8 quarts compost, earthworm castings and/or composted chicken or steer
manure
4 quarts sphagnum peat moss
4 quarts perlite
4 quarts builder’s sand
1 cup all-purpose fertilizer mix (she has another recipe for this*)
3 tablespoons ground dolomitic limestone

2 pounds fish meal or crab meal
1/2 pound greensand
1/2 pound steamed bonemeal
1 pound rock phosphate
1 pound kelp meal

Virginia CooperativeExtension also has information on soil mixes for growing edible crops in containers:

“A fairly lightweight mix is needed for container gardening. Soil
straight from the garden usually cannot be used in a container because it
is too heavy, unless your garden has sandy loam or sandy soil. Clay soil
consists of extremely small (microscopic) particles. In a container, the
bad qualities of clay are exaggerated. It holds too much moisture when
wet, resulting in too little air for the roots. Also, it pulls away from
the sides of the pot when dry.

“Container medium must be porous in order to support plants, because roots
require both air and water. Packaged potting soil available at local
garden centers is relatively lightweight and may make a good container
medium.

“For a large container garden, the expense of prepackaged or soil- less
mixes may be quite high. Try mixing your own with one part peat moss, one
part garden loam, and one part clean coarse (builder’s) sand, and a
slow-release fertilizer (14-14-14) added according to container size.
Lime may also be needed to bring the pH to around 6.5. In any case, a
soil test is helpful in determining nutrient and pH needs, just as in a
large garden.”

Meyer Lemon tree care guidelines

I did not feed my Meyer lemon plant this summer. The leaves
are light green. Should I feed it before I bring it inside for the
winter or wait until mid-winter?

The pale leaves make me think perhaps there is a nutrient imbalance or
deficiency, but it would be hard to say precisely via e-mail. Pale leaves
might also mean lack of exposure to sunlight. Are the pale green leaves
newer or older leaves? According to the University of Santa Cruz Center for Agroecology, a nitrogen deficiency would be evident if older leaves
lower down on the tree were turning yellow.

According to the book Citrus by Lance Walheim (Ironwood Press, 1996),
nitrogen is the only nutrient which citrus plants need on a regular
basis, and Meyer lemon needs less than other lemon species. A lot depends
on your soil. If the soil is alkaline, this may “tie up” micronutrients
and keep them from being absorbed by the tree. You might want to take
samples of the leaves and soil to your local county extension agent.

The Walheim book offers the following advice on growing citrus in
cold-winter climates:

Make slow transitions from indoors to outdoors and back…The transition
period should last at least three to four weeks. Before bringing the
plant indoors, move it to a location where it receives less direct
sunlight. Gradually decrease exposure to the sun. Unless you’ll be
keeping the plant in a cool location, don’t wait to move plants after the
weather has become cold and your heater is on indoors. ..Just before
moving a plant indoors, hose it off to clean the foliage…

The conditions found in most homes in winter–low light and warm, dry
air–will cause many citrus trees to turn yellow and drop their leaves
and fruit…To prevent his, place the trees in a cool, well-lit location
and try to maintain high humidity. A cool greenhouse, where temperatures
stay above freezing, is ideal…To increase humidity…place the tree on
a large tray covered with rocks and filled with water. Replace the water
as it evaporates.

General indoor care guidelines, also from the Walheim book:

Do not overwater. Let soil dry out partially between waterings.

Fertilize lightly. About 3-4 weeks before taking trees back outside,
increase fertilizer.

So I don’t think you need to fertilize the tree
before you bring it inside. Here is a link to a question from our library’s database, with details on fertilizing Meyer lemon.

Check often for signs of insects.

pruning Red Gravenstein

Could you provide me with information on pruning Red Gravenstein?

encouraging orchids to bloom

All but one of my orchids are blooming this season! What could be the cause of the one orchid not blooming?

First of all, congratulations that you have all but one of your orchids
blooming. Orchids are plants with very particular needs, as you well know. I
have found two possibilities as to why your one orchid will not grace you with
its flowers: light and space. However, there are other possibilities as well,
which I will try to address.

Perhaps this one plant is not receiving the amount of sunlight it needs to bloom
and the others are. Are all your orchids the same species or variety? If so, are
they all in the same area of your house; i.e. same window? If they are not the
same species or variety, then they may require different amounts and levels of
intensity of light. Are they growing in a window with natural light or are you
growing them under artificial light? If you are using artificial light, orchids
do require dark as well as light. Orchids “should not receive more than 14 hours
of artificial light a day. More than that will prevent them from blooming.”
(Orchid Growing Basics by Dr. Gustav Schoser, Sterling Publishing Company, 1993)

Are you using a fertilizer? If so, and the first number is a lot higher than the
second or third (such as 15-5-5), it is likely that the plant is receiving too
much nitrogen. This will do wonders for the green leaves but nothing to promote
flowering. A fertilizer with the numbers closer together (such as 10-12-10) will
be more balanced and would be recommended. Are you monitoring the temperature?
“The effects of temperature changes are most clearly observable in the Cymbidium
orchids. Flower production begins when daytime temperatures are about 68 degrees
and nighttime temperatures are around 50-57 degrees. Phalaenopsis schilleriana
and its hybrids will only bloom when the nighttime temperature is under 68
degrees for at least 2-3 weeks.” (Orchid Growing Basics)

Here is an excerpt from a frequently asked question and answer web page from a
commercial grower: beautifulorchids.com.

Q: I am growing my phalaenopsis orchid in the house but they never bloom. What can I do?

A: The most common reason for any orchid not to bloom is insufficient light.
Move your phalaenopsis plants to a window where they will receive strong, but
indirect light (near a south-facing window is ideal). You might also try
lighting your plants with a fluorescent light fixture placed about 1-2 feet
above the foliage. Give up to 12 hours of supplemental light per day.
Phalaenopsis will also develop flower spikes in response to a cool period of
about four weeks with night temperatures of 55F. After the cool treatment, raise
the night temperature back to the normal 60-65F minimum. See if these changes to
your growing conditions help to stimulate your plants to bloom.

Another page on the same site more clearly defines good vs. bad light. They
explain that too little light may prevent the plants from blooming. They also
list specific orchids that prefer low light and those that prefer moderate to
high light.

The Brooklyn Botanic Garden All-Region Guides: The Gardener’s Guide to Growing
Orchids (2004) Handbook #178 has good information regarding light
requirements on a variety of orchids. It is noted in this book that “light is
undoubtedly the most important factor in determining whether or not an orchid
will flower.” The American Orchid Society’s page on “Light, the Key to Successful Blooming” should also be helpful.

Also, there is a possibility that the one orchid has outgrown its pot faster
than its companions and has a need for more space (and possibly more nutrients).
“Most orchids usually only bloom from new growth” (Your First Orchids and How
to Grow Them published by the Oregon Orchid Society, Inc 1988). “An orchid is in
need of repotting when the leading pseudobulb or growth has reached the rim of
the pot and there is no room for future development. (The Gardener’s Guide to
Growing Orchids by Wilma and Brian Rittershausen, David and Charles Publishers
2001) If you are getting new shoots but they are growing over the edge of the
pot and breaking off, this would also be a sign for the need to repot.

The Gardener’s Guide to Growing Orchids by Wilma and Brian Rittershausen, and The
Brooklyn Botanic Garden All-Region Guide and Orchid Growing Basics by Dr. Gustav
Schoser, offer good directions on repotting. The Schoser title even offers
recipes on how to make your own potting mixes.