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Plant Answer Line questions and answers.

Overwintering Ensete ventricosum

I recently purchased an Ensete ventricosum, which I will plant in a large
container. I live in Bellevue. Should I consider this
plant an annual only? Or is there a way I can overwinter the plant, so that I can enjoy it next year? I don’t have a green house. Would it work to bring it into the garage? If I bring a potted plant into the garage, doesn’t it need water and light? Or could I put hay over the container and leave it outside?

 

I could not find any information that suggested overwintering this particular
plant outside would be successful. In Bellevue, some other species can be
overwintered outdoors, like Musa basjoo, but E. ventricosum is more tender.

Fortunately, I did find several resources about overwintering your plant
indoors, so you may be able to enjoy your plant over several seasons. The
Missouri Botanical Garden information suggests several methods for overwintering
E. ventricosum. Here is an excerpt:

 

  1. Bring container plant indoors in fall before first frost and place container
    in a large sunny room for overwintering as a houseplant, with reduced water and
    fertilization;
  2. If container plant is too large to bring inside as a houseplant, cut foliage
    back to 6-8″ in fall after first frost, and store container in a cool, dark,
    frost-free corner of the basement until spring, with periodic addition of a
    touch of moisture as needed in winter to prevent the soils from totally drying
    out;
  3. If container plant is too heavy or too large to bring inside, remove
    plant from container in fall before first frost, wrap roots in plastic and store
    in a cool, dark, frost-free corner of the basement until spring (foliage may be
    trimmed back or left on the plant and allowed to brown up in the normal course)

 

If you don’t want your E. ventricosum as a houseplant, overwintering in the
garage seems possible. Given that the Missouri Botanical Garden recommends a
basement and the plant will be basically dormant, meaning it will not want much
water or light, your garage will probably be fine as long as it is warm enough.

The Royal Horticultural Society suggests growing it in a sheltered spot outside, or overwintering it in a well-ventilated temperate greenhouse. Another RHS page no longer available online makes these recommendations about temperature:

To overwinter Ensete, our glasshouse is kept at 16 C (61F) by day and 12C
(53 F) at night – at lower temperatures, lifted plants are prone to rotting. The
lower the overwintering temperature, the earlier Ensete should be lifted and
established in their winter containers, and the drier they should be kept
subsequently.

The site of Cool Tropical Plants includes an illustrated tutorial of lifting Ensete for the winter, however, simply notes that the minimum temperature should be 3 C (about 37 F).

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Treating peach leaf curl

Have you any advice about how to combat peachtree leaf curl using
natural methods at this stage in the season? I’ve just read about the
use of thyme or oregano oil, but no advice on amount used. I would be
glad of any help!

 

The information I was able to find about thyme oil as a treatment for
Taphrina came from an application to the U.S. Patents Office, so I cannot
speak for its efficacy.

The U.S. Department of Agriculture’s Agricultural Research Service offers
research on the use of plant essential oils in postharvest disease control, too. My impression is that the efficacy of these plant-based oils is still being studied and evaluated.

I also found information on managing peach leaf curl (Taphrina deformans)[formerly available online] from
the National Sustainable Agriculture Information Service which suggests
using lime sulfur, acceptable by U.S. organic standards, though European
standards may differ. Below is a more substantial excerpt:

 

The life-cycle diagram above in Figure 2 shows that the infection period
for leaf curl is when new leaves start emerging from buds in the spring.
Spraying after the buds have opened is ineffective, because infection
takes place as the young leaves emerge, and the fungus develops inside
the leaf.

Accordingly, sprays must be applied during the trees’ dormant
period after the leaves have fallen and before the first budswell in the
spring. Many orchardists spray just prior to budswell during the months
of February and March. Orchards with a history of severe peach leaf curl
benefit from a double application: in the autumn at leaf fall and again
in late winter or early spring just before budswell.

Fortunately for the organic grower, lime sulfur is one of the most effective
fungicides for control of peach leaf curl and is allowed in certified organic
production . Bordeaux and copper fungicides are also approved for certified
organic programs and are effective as well, but not as effective as
lime-sulfur.

Pscheidt and Wittig (6), performed trials comparing Kocide, lime-sulfur,
several synthetic fungicides, and Maxi-Crop seaweed for leaf curl
control. Lime-sulfur and one of the synthetics (ziram) were best, roughly
twice as effective as Kocide. Seaweed sprays, despite positive anecdotal
reports, were completely ineffective.

Severe leaf curl infection can cause the tree to shed many of its leaves
and to replace them with a second flush of growth. At this time the tree
will benefit from a light feeding with a quickly-available soluble
fertilizer such as compost tea or fish emulsion to help it recover.

There are various levels of resistance to leaf curl among varieties;
however, because of the relative ease of controlling the disease,
breeding for resistance has not been a priority. Redhaven, Candor,
Clayton, and Frost are some of the cultivars with resistance to leaf
curl, though none is immune. In contrast, Redskin and cultivars derived
from it are susceptible.

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The City of Seattle’s Integrated Pest Management Solutions pages for
landscaping professionals also suggests methods of prevention and
control. Damage may be reduced by sheltering the tree from winter and
early spring wet. If only a few leaves are affected, they may be removed
by hand. Peach leaf curl does not usually kill the tree, though fruit
yield will be reduced. This resource also mentions using copper
fungicides and lime sulfur when the tree is dormant.

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Growing and caring for Zamioculcas zamiifolia

What are the cultural requirements for Zamioculcas?

 

Zamioculcas is in the plant family Araceae, and its common name is the Aroid palm. According to the Sunset Western Garden Book (2007), this tropical African perennial which resembles a cycad or a palm will grow slowly to 4-5 feet high by 3-4 feet wide. Grown outdoors, it prefers partial to full shade, but indoors you should provide bright filtered light. It should be placed on a tray of moistened pebbles, and misted occasionally. During active growth, keep the soil evenly moist, and give it balanced fertilizer once a month. During the fall and winter months, do not fertilize, and only water when the top inch of soil becomes dry. In summer, the plant may be moved outside to a shady spot. All parts of this plant are poisonous.

You can find discussion among growers of Zamioculcas zamiifolia (sometimes called “the ZZ plant”) on the University of British Columbia Botanical Garden Forum.

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Planting bare root roses

When should I plant bare root roses?

 

The Seattle Rose Society
suggests planting in March. The roses should be stored in a cool dark place if they cannot be planted right away.

Other recommendations include soaking the roots before planting (8-12 hours), and trimming off damaged or diseased roots. Try to maintain 3-5 canes per plant, and prune back to 3-5 buds per cane.

Dig a hole wide and deep enough to accommodate the roots. Make a cone-shaped mound of soil in the center of the hole to support the plant. Fill the hole 2/3 full of soil and add water to make a slurry–this gets between the roots. Do not tamp the soil. When the water drains, add more soil and repeat the water fill process until you reach the original soil surface (ground level).

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Winter watering

Can you tell me, what’s the deal with watering in winter? I’ve heard that foundation plants which don’t catch the rain under the eaves must be watered even in wintertime. Someone else says that watering anything in winter subjects it to freezing.

Now I’m in a quandary. I don’t want my plants to freeze to death, nor do I want them to die of dehydration. So what’s the answer?

 

According to Colorado State University Extension, you do need to water if there has not been snow or rain. You should water when the temperature is above freezing and the soil is not frozen. You should water early in the day so that the water can soak in before it gets cold overnight and freezes.

Here in the Puget Sound area we do not have freezing temperatures very often so you should go ahead and water, especially those plants under the eaves.

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On propagating Paulownia

How can I propagate a Paulownia tree?

 

Something to consider before propagating this tree is its invasive potential. Depending on your location, increasing the population of Paulownia trees may not be wise. The U.S. Department of Agriculture lists Paulownia tomentosa as an invasive species. If you are in King County in Washington State, you may be interested to know that the Center for Invasive Species shows this tree in its Early Detection and Distribution map.

Nevertheless, directions for propagation are available. Peter Thompson’s book, Creative Propagation (2nd edition, Timber Press, 2005), states that Paulownia is best propagated by seed in the spring, or by semi-mature root cuttings laid horizontally just below the surface of the soil. I suggest that you think twice before propagating this tree.

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Growing Epimedium

Can you recommend some Epimedium species and tell me what kind of conditions they prefer?

 

The resources I consulted say that most Epimedium species prefer part shade, and most are evergreen. Some will tolerate a partly sunny site as long as the soil does not dry out.

Epimedium perralderianum has bronze leaves that turn green and last throughout the year. It blooms in March/April.

Epimedium x rubrum prefers shade, so if your site is partly sunny, this might not be the ideal choice.

Collectors Nursery in Battleground, WA, also carries several varieties.

One gardening website, Paghat’s Garden, has especially good information.
The site developer recommends in particular the following varieties:
Epimedium x versicolor ‘Sulphureum’, or Yellow Epimedium – for its evergreen foliage
Epimedium grandiflorum ‘Lilafee’ – for quite striking lavender flowers and evergreen foliage

Richie Steffen, curator of the Elisabeth C. Miller Garden, is the author of “Epimediums” Queens of the Woodland” published in Pacific Horticulture, April 2008.

A recent book, The Plant Lover’s Guide to Epimediums by Sally Gregson, has excellent illustrations as well as information.

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Native plant resources

I’m looking for a good publication on plant communities for my
area, Whatcom County in northwest Washington. We want to encourage plant communities that will do well here, and have about 5 acres to work with. Can you make a suggestion, please?

 

If you are interested in
plants native to Washington, I recommend these two books:

Kruckeberg, Arthur R., Gardening with Native Plants of the Pacific
Northwest, University of Washington Press, Seattle, 2nd edition, 1996.

Pettinger, April, and Brenda Costano, Native Plants in the Coastal Garden – A
Guide for Gardeners in the Pacific Northwest , Timber Press, Portland, OR,
revised edition, 2002.

The Washington Native Plant Society is also a good resource.

If you are interested in plants that will grow well in your area, but are
not necessarily native to Washington State, please check out the Miller Library’s
booklist about gardening in the Pacific Northwest.

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Aleuria aurantia

I have several beautiful orange fungi growing in my two year
old garden. They appear mostly between stepping stones (full sun) which
have a deep underlay of gravel and sand, and also in a nearby bed which
is semi-shady. Is this
an indicator of an extreme soil condition that I should remedy? Where
can I learn more?

 

Most likely, this mushroom is Aleuria aurantia, orange peel fungus or
golden fairy cup.
This species is widespread and common, often growing along roads or paths.
It fruits from late fall to early spring.

It doesn’t seem to be a problem for gardens….I would enjoy it as an added
bit of fall color when it pops up in your garden.

Here is a
link to a website in California with a nice picture and some information on Aleuria aurantia.

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Pruning clematis

There is a very large evergreen clematis starting to devour my detached garage. How far back can I cut this and when should I prune it back? It’s one of the first early spring bloomers with white flowers, possibly armandii? But I am uncertain…I need help since I don’t want to butcher it and lose it, but it needs a big haircut!

 

Clematis armandii does have the reputation for taking over the world. According to the American Horticultural Society’s Practical Guide on clematis (Clematis, by Charles Chesshire, 1999),
you can prune it AFTER is has finished flowering, which in Seattle, it normally does by the end of March. While this type of clematis can be pruned in late winter, it flowers on the previous year’s wood, so pruning at that time may remove buds and prevent flowering that spring.

Step 1 – remove any dead, dying, damaged, or deranged shoots.
Step 2 – they suggest that no real pruning is necessary but you can cut it back to control its growth. But you do NOT want to cut it all the way back into old dark, woody growth.
Prune directly above a pair of strong side shoots.
Step 3 – you will need to keep after it each year to avoid a build up of tangled growth.

Fine Gardening has an article by Lee Reich on pruning clematis here.

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