All about Magnolia grandiflora ‘Alta’

I was reading an article in the local paper that mentioned Magnolia grandiflora ‘Alta’ and was hoping that you could tell me more about and its hardiness in the Pacific Northwest and what its mature dimensions would be.

Magnolia grandiflora ‘Alta’ is a trademarked Monrovia introduction. According to their website, it is “very slow growing to 20 ft. tall, 9 ft. wide in 10 years.” Since this is a relatively recent introduction, there is not going to be much information about its hardiness in our area until more gardeners have grown it and shared their experiences. The longevity of the species Magnolia grandiflora and its cultivars can only be estimated (between 50-150 years, according to SelecTree.) Trees grown in urban settings are often affected by root disturbance, pollution, and the like, so their lives may be somewhat toward the short end of the expectancy range.

The local website of Great Plant Picks lists two different cultivars of Magnolia grandiflora, which may give you some idea of how well they do in our area. Here is an excerpt:

“Provide southern magnolias with good drainage and full to partial sun. They thrive in hot spots, where the extra heat encourages better flowering. These flowering evergreens prefer well-drained, sandy soil, but they tolerate average garden soil. Best growth and flowering requires occasional summer watering, but once established, southern magnolias withstand considerable drought. Garden gently under magnolias, for they have fleshy roots that can easily be damaged. The best approach for companions plants is to tuck in natural spreaders and let them flourish untouched.”

From my observations, they do not do well in the occasional winters when we have heavy snowfall, as their evergreen leaf-laden branches are prone to breaking under the weight of snow. Otherwise, they seem to survive here.

pine needles turning yellow and dropping

Recently we noticed that one of our evergreen trees has a lot of needles that are turning yellowish brown and dropping off. I would say about 25% of the needles are affected, some in the middle of the branches, some at the ends. The needles are about 3 1/2 inches long and are in bunches of five – I think it is a pine.

Is this normal for that type of tree? Or is it more likely the tree is stressed for some reason and we need to deal with it?

This will be a lengthy answer and I will assume you live in the Pacific Northwest—the following information will not apply to other areas.

In order to get an accurate diagnosis you will need to take a sample of your plant (including both healthy and affected parts if possible) to a Master Gardener clinic.

Meanwhile, to learn about diseases common to pines in the Pacific Northwest, go to the Pacific Northwest Plant Disease Management Handbook and search using the term pine. There are several possibilities with good photos. Remedies are included with each disease.

Insect information is more difficult to get, so following are the most likely-sounding pests:

1. Pine (Pinus) – Black pineleaf scale (Nuculaspis californica)

Pest description and crop damage
Mature scales are almost circular, 1/16 inch in diameter, and yellowish brown to black. Young hatch in spring and
summer. Scale feeding is restricted to the needles and results in their becoming splotched with yellow patches. Heavy infestations cause premature needle drop and may result in death of the tree. Affected trees often display a thin crown, yellow or reddish coloration, and a shortening of the needles. This insect attacks various species of pine, ponderosa most commonly, as well as Douglas-fir and hemlock.

Biology and life history
This scale overwinters as an immature. The crawlers start to disperse to fresh foliage in spring. There may be one to three generations per year.

Management-cultural control

Trees under stress tend to be particularly susceptible to attack, as are trees growing in dusty conditions. Avoid creating these types of conditions.

Management-chemical control (home)

Dormant season:

Apply with enough water to cover the entire tree thoroughly.

1. horticultural oil. Apply during delayed-dormant period.

Growing season:

insecticidal soap

2. Pine (Pinus) – Eriophyid mites (Trisetacus spp.)

Pest description and crop damage
Eriophyid mites are tiny, wormlike, whitish or tan mites which feed under bud scales or in the needle sheaths, often
between the needle bases. Symptoms of eriophyid mite infestations include yellowing, distortion, and stunting of new needles, and development of numerous buds where a bud has been infested (rosetting). Severe infestations
may kill needles and cause needle drop, leaving naked branch tips. Rosettes may develop into witches’ broom growths. Two-needle pines, particularly lodgepole or shore pine, are affected.

Management-cultural control

Prune out heavily infested growths.

3. Pine (Pinus) – European pine shoot moth (Rhyacionia buoliana)

Pest description and crop damage
Adult moths are reddish-orange with silver markings on the wings. The mature larvae are about 5/8 inch long and
reddish-brown with black heads. The larvae of the European pine shoot moth feed on tips of branches, boring first into needles or bud bases, then into the shoots. Infested tips are covered with pitch-covered webbing, often develop a characteristic “shepherd’s crook” shape, and may die back. Infested needles are yellowed near the twig tips and eventually turn brown and die. All pines are susceptible, especially two- and three-needle species.

Biology and life history
The insect overwinters as larvae in the mined buds, covered with resin-coated webs. The adult moth lays eggs on new shoots near leaf bases in the late spring. The larvae hatch and bore into the needles, which turn brown by summer. By midsummer, they are mining in the buds and cease feeding by August. There is one generation per year.

Sampling and thresholds: Check for yellowed leaves at shoot tips in midsummer.

Management-cultural control

Prune and destroy infested tips in spring, before adults emerge. Be sure to prune far enough down the branch to remove the insects.

Management-chemical control (home)

1. azadirachtin (neem extract)

plants for full sun that provide a lush year-round garden

I have an asymmetrical flower bed in front of my house. It faces southeast and the house is white, with reflection of light. I purchase plants for full sun but they tend to get fried. I am interested in finding perennials to provide interest 12 months of the year. I prefer shrubs with a variety of texture. Plants that attract butterflies would be nice, and any grasses that are known not to grow out of control. What plants do you recommend that would give me a lush, year-round garden?

You may want to plant a mixture of perennials and shrubs, particularly those which tolerate bright light. An excellent book full of lists of plants is Ray and Jan McNeilan’s Pacific Northwest Gardener’s Book of Lists (1997). This book includes lists such as Shrubs for Interest in Each Season (pp.62-64), and Herbaceous Perennials for Full Sun All Day (pp.138-139).

I think you may find many of the other lists in this book valuable as you design your flower beds.

The Great Plant Picks website has lists of many different plants that do well in Northwest gardens, including pictures and descriptions.

There are quite a few books which address the issue of providing year-round color and interest in the garden, such as Adrian Bloom’s Year-Round Garden: Colour in Your Garden from January to December (Timber Press, 1998) and his Bloom’s Best Perennials and Grasses : Expert Plant Choices and Dramatic Combinations for Year-Round Gardens (Timber Press, 2010). The Miller Library also has booklists on topics like Winter Gardening and Perennials which may be of use to you.

And, here is an article entitled “Create a Butterfly Garden” (S. Lamb et al., January 2002) from Oregon State University.

Visiting local gardens throughout the year and noting the plants that appear to be thriving may help, and a trip to your local nursery can give you lots of ideas and information. The Center for Urban Horticulture and the Washington Park Arboretum both feature seasonal plant highlights.

managing aphids on Meyer lemon trees

My Meyer lemon has aphids all over it and has lost its leaves! I just brought it inside for the winter. What can I do?

The aphids were more than likely already there, even if not enough for you to notice, and once inside the warm(er) house they multiplied. Aphids do love citrus plants. The leaves probably fell off due to the temperature change they experienced coming indoors.

The following information was found on p. 278 of the 2001 edition of the Sunset Western Garden Book:

Citrus in containers. Fertilize monthly from midwinter to mid-autumn with high-nitrogen liquid fertilizer, containing chelated zinc, iron, and manganese. Potted citrus … in cold-winter regions: shelter plants in winter; a cool greenhouse is best, but a basement area or garage with good bright light is satisfactory.

Many of the common products sold in nurseries or garden centers contain the trace elements listed in the Sunset info above. Also, there are specific formulations for citrus available, also carried by many nurseries and garden centers.

…Sunset Western Garden Book continued…Citrus as houseplants. No guarantee of flowering or fruiting indoors, though plants are still appealing. ‘Improved Meyer’ and ‘Ponderosa’ lemons [other citrus names omitted] are most likely to produce good fruit. Locate no farther than 6 ft. from a sunny window, away from radiators or other heat sources. Ideal humidity level is 50 percent. Increase moisture by misting tree; also ring tree with pebble-filled trays of water. Water sparingly in winter…

I grow 2 Meyer lemons and find that they do best outside until the temperature goes down into the 20s. They are pretty hardy. The aphid problem is not a problem outside until spring.

If you have a sun porch at your house, that might be a great place to put the lemon in winter.

As for the aphids, Colorado State University Extension provides information on insect control using insecticidal soap. You can purchase it or make your own: 1 teaspoon of soap (the mildest you can find) per quart of water, sprayed on both sides of the leaves and on growing surfaces.

Opuntia fragilis and its common names

Does the Opuntia fragilis in the Puget Sound carry a vernacular name of dune or shore prickly pear?

The most common vernacular name of the cactus Opuntia fragilis in Washington is brittle prickly pear. When I searched for dune or shore prickly pear, I found these common names connected with other species of Opuntia.

For more information about Opuntia fragilis, see the Washington Flora Checklist and the USDA Plant Profile.

on diseases that affect junipers

My Sky Rocket junipers are declining. To me it looks like mite damage accompanied by winter damage. The top of the plant is still healthy looking. There are spider mites present. It does not resemble phomopsis, but could be phytophthora. Please let me know what you think.

I checked Diseases of Trees & Shrubs by Sinclair, Lyon and Johnson and Juniper virginiana does not get phytophthora (or at lease this good authority does not list that disease.) It does list a number of other diseases including blight, canker, phomopsis, among many others.

The HortSense website of WSU Cooperative Extension mentions Juniper webworm, which creates heavy webbing, which could resemble mite webbing.

Of course it could be winter damage, like you guess or nitrogen deficiency if the Ph is high (near a lot of concrete?), or salt damage (from melting ice in past winters?).

You should take a sample in to a Master Gardener clinic. If they do not know the cause, you can ask that they “submit it to the diagnostic center at the Center for Urban Horticulture.”

Locate a Master Gardener Clinic within King County at this website.

ripening pumpkins off the vine

I have two pumpkins that I grew. One is 5 lbs. and the other is 8.5 lbs. They are only orange on the the side that was on the ground. I have already picked them as the vines were dying back. Will they ripen more? And how will I know when they are ripe? I have them in the garage. I want to use them to make pies.

I found the following on the web page of Pumpkin Nook, a commercial site.

Extending the season- If your pumpkins are still on the vine, they are best left there. Cut away any leaves that may block the sun, however small. In the waning hours of daylight, the fruit can use every ray it can get. If Jack Frost is about to stop by, get some large plastic sheeting. Cover the fruit and the vine. Anchor the plastic with bricks or rocks to keep the wind from blowing it off. If the next day is going to be very cold, you can leave it on all day. If not, remove it.

Ripening out of the patch- As previously mentioned, green and partially orange pumpkins will ripen up with sunlight, warmth, and time. Just follow these steps:

Remove the pumpkins from the patch and wash off the dirt.
Place your pumpkins on a warm, sunny deck or patio.
They can also be brought inside. If you bring them indoors, make sure there is good air circulation to minimize the chances of mold and rotting.
Turn the greenest side of the pumpkin towards the sun.
Rotate the pumpkin from time to time to allow the sun to reach the greener parts of the pumpkin.
If left outdoors, bring them in at night to keep the pumpkins’ temperature warmer.

Here is more information (now archived), from the University of Illinois Extension.

on protecting bulbs from wildlife

I am trying to plant some bulbs but they are being disturbed and eaten by the squirrels. Do you have any tips and tricks to protect my bulbs from being snacked on?

Here is a 2009 article by Sally Ferguson in the online archive of BC Living magazine on preventing squirrel snacking:

Excerpt:
Q. How do I keep squirrels from digging up bulbs?

A. Squirrels can be terrible pests! They won’t bother daffodils and other narcissi bulbs (which taste terrible to them!), but they find tulips and crocus in particular to be worth the effort to sniff out and dig up.

The only sure-fire way to protect tulips and crocuses and other tasty bulb treats from squirrels is to lay wire mesh such as chicken wire on top of the bed. The squirrels can’t dig through the mesh and the flowers will grow neatly through the holes.

Bulbs are most vulnerable in fall immediately after planting when the soil is still soft and worked up. Digging then is easy! Squirrels often “chance” upon bulbs when burying their nuts in soft ground. Or they are attracted by “planting debris” such as bits of papery bulb tunics and other bulb-scented bits from the bulb bags. Don’t advertise your plantings: clean up and keep those squirrels guessing!

Here’s one neat trick that garden writer Judy Glattstein has found to work: after planting new areas, lay old window screens in frames on the ground, covering the newly-worked up soil. The screen weighs enough to
foil the squirrel, but allows for air circulation and rainfall. Once the ground has settled, remove the screens and store for future use.

Another remedy that some find successful is to feed the squirrels during the fall and winter. The theory is that the local squirrel population, when offered a handy plate of peanuts or other easy-to-get treats will leave your bulbs alone. At the White House, the gardeners put up six peanut-filled feeding boxes to satiate the furry denizens there — and reduced squirrel damage on bulb beds by 95 percent!

Many gardeners claim success with commercial repellents, but these are often sticky and unpleasant to deal with, or wash away in the rain.

Home remedies include sowing cayenne pepper into the soil or on the bulbs before planting and scattering moth ball flakes on the ground. You will find advocates and detractors of both methods. A favorite Dutch remedy is
to interplant Fritillaria imperialis. This tall dramatic plant gives off an odor that squirrels (and deer too, reportedly) find repellent. There is a book on the subject, Outwitting Squirrels, by Bill Adler, Jr. (1988 Chicago Review Press, Chicago, IL). It’s aimed at owners of bird feeders, but you may find some helpful hints.

propagating tree peonies from seed

I have a tree peony that started as a seedling from a plant of a friend gave me 8-10 years ago. I would like to try to propagate mine from seed. From the little I’ve read, it seems this is a difficult process. Can you help me?

I believe you are correct that propagating tree peonies from seed may be a little challenging. It can be done, but home gardeners may find it easier to propagate by grafting, which is described by a link at the end of this answer.

The American Horticultural Society’s Plant Propagation, edited by Alan Toogood (DK Publishing, 1999) rates seed propagation of deciduous tree peonies as moderate in level of difficulty. Another thing to bear in mind is that it will take several years before you see flowers on your new plants. In [late] summer, you would sow fresh seeds in pots and “provide two periods of chilling, such as two cold winters, with warmth between. Seeds are doubly dormant (roots emerge in the first year and seed leaves in the second). Guard against mice: they love the seeds.”

Another description of propagating from seed may be found in Jekka McVicar’s book Seeds (Lyons Press, 2003):

This seed has a double dormancy, producing roots in its first year and
leaves in its second. It needs two cold periods, with warmth in between.

Collect ripe, fresh seeds in early autumn. Sow individually in pots,
using standard soil-less seed mix, either peat or peat substitute mixed
with coarse horticultural sand. Mix to a ratio of 1 part soil-less mix +
1 part sand. Cover with coarse grit, then place outside exposed to all
weathers. Visible germination occurs during the second spring. Grow on in
a cold frame for 2 years before planting out.

Excerpt on propagation methods from Plants for a Future database:

Seed – best sown as soon as it is ripe in a cold frame.When sown fresh,
the seed produces a root about 6 weeks after sowing with shoots formed in
the spring. Stored seed is much slower, it should be sown as soon as
possible in a cold frame but may take 18 months or more to germinate. The
roots are very sensitive to disturbance, so many growers allow the
seedlings to remain in their pots for 2 growing seasons before potting
them up. This allows a better root system to develop that is more
resilient to disturbance.If following this practice, make sure you sow
the seed thinly, and give regular liquid feeds in the growing season to
ensure the plants are well fed. We usually prick out the seedlings into
individual pots as soon as they are large enough to handle, and then grow
them on in a cold frame for at least two growing seasons before planting
them out when they are in growth in the spring.

The Heartland Peony Society has an illustrated tutorial on grafting tree peonies, should you wish to try this method.

drought-tolerant container planting

Our neighborhood has a small planter area at its entrance. There is no water supply to this area, but a nearby resident is willing to water occasionally. The soil contains much clay. We would like to plant a few drought-tolerant annuals to add color and supplement the more permanent shrubs–such as boxwood–planted in the area. Can you recommend some plant choices? How could we amend the soil to best hold water during the upcoming dry months? Would a commercial product such as “Quench” be of any value, in addition to organic mulches?

I found the following article by Nikki Phipps on GardeningKnowHow.com about drought-tolerant container planting. Here is an excerpt:

“…many plants not only thrive in containers but will tolerate hot, dry conditions as well. Some of these include annuals like marigolds, zinnias, salvia, verbenas, and a variety of daisies. Numerous perennials can be used in a xeriscape container garden such as Artemisia, sedum, lavender, coreopsis, Shasta daisy, liatris, yarrow, coneflower and more. There is even room for herbs and vegetables in the xeriscape container garden. Try growing oregano, sage, rosemary, and thyme. Vegetables actually do quite well in containers, especially the dwarf or bush varieties. There are also numerous ornamental grasses and succulents that perform nicely in containers as well.”

This Brooklyn Botanic Garden’s 2001 article provides a list of drought-tolerant plants for containers.

I had not heard of Quench, but since it is cornstarch-based, it is certainly preferable to the hydrogel and polymer products which are more widely available. I found an article by garden writer Ann Lovejoy in the Seattle P-I (June 3, 2006) about Quench. Here is an excerpt:

With pots and containers, mix dry Quench into the top 12 inches of potting soil in each pot and top off with plain compost. Few roots will penetrate deeper than a foot, so it isn’t very useful down in the depths of really big pots unless you are combining shrubs and perennials.

I would not recommend hydrogels or polymers as a soil amendment. Professor Linda Chalker-Scott of Washington State University has written about these products and their potential hazards. Here is a link to a PDF.

You could consider applying a liquid fertilizer (diluted seaweed-fish emulsion would work) to your containers once every week or two during summer. Here is an excerpt on some general information on container maintenance, from a no longer available Ohio State University Extension article. Excerpt:

“Once planted, watering will be your most frequent maintenance chore, especially if you are growing plants in clay containers. On hot, sunny days small containers may need watering twice. Water completely so that water drains through the drainage hole and runs off. Water early in the day.

“If you incorporated a slow release fertilizer into the potting mix, you may not need to fertilize the rest of the season; some of these fertilizers last up to nine months. You can also use a water-soluble fertilizer and apply it according to the label directions during the season.

“Mulch can be applied over the container mix to conserve moisture and moderate summer temperatures. Apply about one inch deep.

“Depending on the plants you are growing, you will need to deadhead and prune as needed through the season. Monitor frequently for pests such as spider mites. Pests usually build up rapidly in containers.”