growing pomegranate trees as a fruit crop in the PNW

I live in Enumclaw, WA which is USDA hardiness zone 8a, and am hoping to grow pomegranate trees as a fruit crop. Can they be grown here or would they need the aid of a greenhouse?

Most of the Pacific Northwest nursery sources for pomegranates (Punica granatum) say that their varieties are hardy in zones 8 through 10. That being said, they may survive our conditions, but they might not have sufficient flowers and fruit set if you are trying to grow them as a crop outdoors. For basic cultural information, see the following, from California Rare Fruit Growers:
“Pomegranates prefer a semi-arid mild-temperate to subtropical climate and are naturally adapted to regions with cool winters and hot summers. A humid climate adversely affects the formation of fruit. The tree can be severely injured by temperatures below 12 degrees F. In the U.S. pomegranates can be grown outside as far north as southern Utah and Washington, D.C. but seldom set fruit in these areas. The tree adapts well to container culture and will sometimes fruit in a greenhouse.”

Purdue University has additional information about growing pomegranate.

According to Trees and Shrubs for Pacific Northwest Gardens by John Grant (Timber Press, 1990), pomegranates need the warmest possible site in our area to flower well (such as near a south- or west-facing wall), and are unlikely to develop ripe fruit.
If you want to grow them for fruit rather than their ornamental qualities, you may need a greenhouse setting. There are some varieties which are more likely to succeed in the Pacific Northwest than others. Check out the selection at Raintree Nursery in Morton, WA and One Green World in Molalla, OR.

getting more fruit from a quince bush

We have a quince bush and we’d like to make quince jelly, but the fruit this year was very small and seedy. We made some jelly, but with the seeds mixed in, since there wasn’t much fruit outside the seed part. Last year, I think we had more quinces and they were larger. We also have a very old pear and an apple tree, and they both had less fruit this year too.

Is there anything I can do to get more fruit from the quince bush? Should it be cut more? Or less? More water? Fertilizer?

Is your quince bush the ornamental quince, botanical name Chaenomeles, or the edible quince, Cydonia oblonga? The fruit of ornamental quince is edible, but tends to be less known for its flavor than that of Cydonia oblonga. To help you determine which quince you are growing, take a look at the following information.

A local gardener’s website, Paghat’s Garden, describes ornamental quince and the use of this plant’s fruit:
“Having been developed for the pre-spring and early spring flowers, not all these shrubs fruit well. But there are also a few cultivars developed in northern Europe with fruit production in mind. Generally the market-variety quinces are trees of a different genus altogether, namely Cydonia oblonga. But species of Chaenomeles were formerly categorized as Cydonia, and their tart fruits are also edible.”
Plants for a Future Database also describes ornamental quince.

There is an essay on edible quince (Cydonia oblonga) by Joseph Postman in Arnoldia (Harvard Arboretum publication), vol. 7 no. 1, which includes some cultural information. The amount of fruit production may vary depending on weather and other environmental conditions.

There are also discussions on the difference between the edible and ornamental quinces and their fruit, such as this one from University of British Columbia Botanical Garden, excerpted here:
“The big fuzzy fruit are the real quinces (Cydonia) and is the only member of its genus. The flowering quinces (eg., Chaenomeles) were once classified with the Cydonia quince trees. I think some Chaenomeles were called ‘Japonica’, but the ‘flowering quince’ name seems the norm now. Unfortunately the abundance of chaenomeles, and use of the name ‘quince’ for the Chaeonomeles contributes to the under appreciation of quince tree and its fruit.”
Another excerpt, from a nursery source:
“Like apricot and peach pits, European quince seeds contain cyanide… Most people know that they must never cook apricot or peach pits when making jam or jelly, but most do not know that this also applies to true quince seed.
Although often called Flowering Quince, Chaenomeles japonica is a very different plant, and it is these fruit that most North Americans are familiar with, although the flavour of the fruit is nowhere near as rich and aromatic as that of the true quince. The seeds of the flowering quince are not particularly dangerous, and may be cooked with the fruit, but I still would not recommend doing so.”

Cornell University also discusses the difference:
“Don’t confuse these quinces with several other quince-like species grown for ornamental purposes. There are many varieties of Japanese quince (Chaenomeles japonica) and common flowering quince (C. speciosa, C. lagenaria), attractive shrubs bearing showy pink, red or orange flowers in early spring.

Most of these ornamentals produce fruits that are hard and nearly inedible, though they have a high pectin content and are occasionally mixed with other fruits in jellies and preserves.”

Sometimes, weather conditions conspire to create a smaller yield of fruit in a given year. You might have had fewer bees and other pollinators. There could have been rain or cold weather and frost at the same time that the plant was in flower, and this could have disrupted pollination. Other factors might be a change in the amount of sun exposure, or an excess of nitrogen-heavy fertilizer which will result in lots of leafy growth and few flowers and fruit.

on the invasiveness of Bear’s breeches

I am wondering how invasive bear’s breeches is? I have heard it can be invasive in the Northwest. Will I be battling roots or suckers constantly? Can it take over any plants near it?

Acanthus mollis, or Bear’s breeches, is not listed as noxious in King County, Washington State, or on the federal list of noxious plants. This is not the same as saying it isn’t potentially aggressive, although I’ve never heard about it being a serious problem here. It is considered invasive in parts of Australia, though.

The Plants for a Future database offers the following information on this plant and its growing habits:
“Plants can become invasive, spreading by suckers, and they are difficult to eradicate due to their deep roots.”

According to the Pacific Northwest site, Rainyside Gardeners, it is sometimes difficult to get this plant to bloom. A Washington State University Extension site says that Acanthus mollis is potentially invasive in climates warmer than ours.
“This species is classified as a groundcover in that any pieces of root cut from the original plant can easily contribute to further plant spread.”

If you want to grow it but are concerned about it spreading, you could try containing the roots with an 8-inch root barrier (similar to what is used to keep running bamboo in check). On the other hand, if you have this plant and decide that you wish to be rid of it, the book Wildly Successful Plants: Northern California Gardens by Pam Peirce and David Goldberg (Sasquatch Books, 2004) says that removing every bit of root over two or three seasons of growth should get rid of the plant. If you cannot eradicate it by continually digging up each new shoot, you may have some luck using a flame weeder (with due caution and appropriate protection). Northwest Center for Alternatives to Pesticides describes how to use this tool.

encouraging daylilies to bloom

How can I get my Stella d’Oro daylily to rebloom? It had a huge show the first 2 weeks of July, now it has stopped.

It has become a large plant. I probably should divide it. When should that be done?

Does it like or need fertilizer? I think it got run-off fertilizer from the roses, and that may be why it is such a large plant.

According to Stefan Buczacki’s The Plant Care Manual (Crown, 1993), you should remove individual flowers as they fade, and cut down flower stems with nothing but fading flowers left. This plant should be divided after three years (do this in fall or spring). This may help with flowering, as overcrowded clumps flower less profusely. Hemerocallis should be mulched in spring and early fall, and you can feed with bulb fertilizer or bone meal in early spring.

Here is a useful link to a factsheet on care for daylilies, from Clemson University.

last frost dates

This year is my first in a house with a yard. I’m very
excited to try my hand at growing some food this year. Many of my seed packets say to plant after the last frost or when the soil reaches certain temperatures. Having never planted anything at the beginning of a season before, I
have no idea when any of these temperatures happen around here! Can someone give me some temperatures and approximate times when they are normally reached?

The last frost date in Seattle can be as early as
March 22, but to be on the safe side, April 15-20 would be more
definitive. This information(now archived) can also be found on the web site of local
gardening expert, Ed Hume. The web site also provides further details. Excerpt:
“The last frost date for an area is the last day in the spring that you could have a frost. The average last frost day is the date on which in half of the previous years the last frost had already occurred (so about half of the time it will not frost again and it will be safe to plant tender plants). Most planting directions are based on the average last frost date. The calendar based directions I give (Now it is time to… etc.) are usually based on an average last frost date of April 1st.

An important thing to realize about last frost dates is that the actual date of the last frost is different every year. It can be much earlier than the average or much later. This is especially important for tender plants that can be killed by a frost. For hardier plants, the average last frost date is more an indicator of general growing conditions than a danger sign.”

The closer to the water the garden is, the milder the temperatures.
The moderating effect of Puget Sound or Lake Washington, for instance,
which results in milder winter temperatures, extends inland for some
distance. If your garden is more than a mile or so from water, that
moderating influence could vary. The last frost date for Vashon Island is
April 5; for the Sea-Tac area, April 9. Again, add at least a week and
check your own garden temperatures and patterns.

on Iris sibirica ‘Mantra’ and its cultural requirements

I am looking for information on a Iris sibirica ‘Mantra.’ I want to know what it looks like, what its cultural requirements are etc. If you can find an image, that would be awesome.

The iris you mention is actually not a Siberian iris. Here is a photo from the Miller Garden website’s alpine collection which lists this as a Pacific Coast iris, rather than Iris sibirica.
This iris won an award of merit from the Pacific Coast Iris Society in 2000. Here is general cultural information from the King County Iris Society.

Pacific Coast Native Iris (PCN), or Californicae (CA), are much sought after in the Pacific Northwest as our climatic conditions are ideal for them. Their graceful and dainty flowers bloom April to June on stems 1′ to 2′ tall, in a wide variety of striking colors and patterns. These irises thrive in the marine coastal climate, with dry summers and cool, wet winters. Plants are very prolific and grow readily from seed. Transplanting, however, can be difficult. They are best moved or divided in the early fall, when root growth is active and can continue well into winter. Plants can also be moved prior to spring bloom.

Transplants must be kept well-watered until natural rainfall can maintain high soil moisture. They should be heavily mulched with bark dust, pine needles or leaves, to prevent frost damage to newly developing roots. Once established, plants are usually tolerant of normal freezes and periods of drought. If frost damage occurs to leaves, wait until well into spring to watch for signs of new growth. PCNs should receive at least a half a day of sunshine.

lack of flowering on Magnolia grandiflora

I have a
very tall, well-established Magnolia grandiflora. The tree is located on
the southeast corner of the lot. Every summer it has produced large white
flowers, but last summer that there weren’t as many blooms, almost
none. It’s left alone and watered spring through summer by a sprinkler system. I have also noticed yellowing of the leaves at the ends of the branches. Usually the leaves
have been dark and green. I’m wondering if it is a lack of nitrogen or food of some sort.

There are a number of reasons that plants may fail to flower, and it
would be difficult to pinpoint precisely why the Magnolia made such a
weak show this past summer. Sometimes, cold temperatures kill off flower
buds (and there were some cold snaps last winter). The tree is not
immature, and it sounds as if it is not pruned improperly, so those
potential causes can be excluded. You also indicate that it is not
fertilized, so it is probably not receiving excessive nitrogen which can
lead to lots of leafy growth at the expense of flowers. I wonder if
anything else in its environment has changed: has the amount of light
changed (any new construction obstructing sun?), or has anything happened
to the soil where it is planted? You might wait and see if flowering
returns to normal this year.

As for the yellowed leaves, that might be a result of winter injury
(desiccation) or drought stress. However, yellow leaves can also be a
symptom of sunburn or lack of light, or nutrient deficiency. See the
link here to University of California, Davis’s page on Magnolia problems. Excerpt:

Mineral deficiencies:
Certain nutrients, in relatively small amounts, are required for healthy
plant growth. Deficiencies can cause tip chlorosis or necrosis or cause
foliage to discolor, fade, distort, or become spotted, sometimes in a
characteristic pattern that can be recognized to identify the cause.
Fewer leaves, flowers, and fruit may be produced, and these can develop
later than normal and remain undersized. More severely deficient plants
become stunted and exhibit dieback. Commercial laboratories can conduct
foliage tests or soil analysis to verify deficiencies.

Identification/Solutions:

Nitrogen and iron are the only nutrients in which woody landscape plants
are commonly deficient. Poor root growth caused by water-logged soil,
root diseases, and nematodes can also cause iron deficiency symptoms.
Fertilize only as needed and only if other problems have been eliminated
as the cause of poor growth. Avoid overfertilization, especially with
high-nitrogen fertilizers. Slow-release formulations of nitrogen or
organic fertilizers reduce some risk of overfertilization. Correcting
deficiencies of minerals is tricky. Apply only the mineral found to be
deficient. In some cases, soil characteristics may exacerbate
deficiencies. Alkaline soil (high pH) often makes iron or manganese less
available; reducing alkalinity with sulfur or organic amendments (peat
moss) may be all that is needed. Some minerals such as iron, manganese,
and zinc are absorbed more rapidly as a foliar spray than a soil
application.

If the environmental causes don’t ring true with your tree’s situation,
you may want to do a soil test to see if there are nutrients which need
to be supplemented.

on the “Burning Bush” plant

I am looking for more information regarding Rubus sanctus, also known
as the Burning Bush at Saint Catherine’s Monastery in the Sinai. I am interested in this plant because my church group is just finishing up our study of the Book of Exodus. And I thought this plant might make a really nice and symbolic gift.

I am beginning to understand that this plant may be rare, or possibly known by
another name?

The problem with English common names for plants of the Bible is that you are at several removes from knowing which plant the original Hebrew text describes. There are some sources which state that “burning bush” refers to Rubus sanctus, but it is more likely that it refers to Senna alexandrina. The Hebrew word in Exodus is sneh, which is the same as the Arabic word for the Senna plant.

Plants of the Bible by Michael Zohary (Cambridge University Press, 1982) says that “the plant in question, specifically named ‘sneh,’ might well have been a real plant in the local flora. As there is no hint in the text that the sneh was a thorny bush, and there are no plants in Sinai or anywhere else that are not consumed when burnt, sneh may be identified linguistically only.” He also suggests that the plant may have been Cassia senna, now renamed Senna alexandrina. There is no native Rubus in Sinai, Egypt, or southern Israel, and the bramble in the monastery garden at Santa Caterina is a cultivated specimen, planted by the monks “to strengthen the belief that the ‘burning bush’ has grown there since the revelation, so completely is sneh equated with brambles in the minds of scholars and Bible lovers.”

While Senna alexandrina may be a bit difficult to obtain, there are other species of Senna more widely available. However, if you wish to grow the Rubus you saw (also referred to as Rubus ulmifolius ssp. sanctus and Rubus sanguineus) as a keepsake from your trip to the monastery, you should go ahead. It is not easy to obtain except as seeds, and it prefers a moist environment.

managing lilacs with bacterial blight

I have a ‘Palibin’ lilac that appears to have a bit of bacterial
blight. I have pruned out the diseased branches. Is it too late to
spray to control the disease? I didn’t do a dormant spray this year,
and haven’t done any preventive spraying to this point, either. If it
isn’t too late, what spray product would you recommend? What else can I do to keep the blight under control?

There are cultural methods of dealing with bacterial blight you should try before using any spray. The information below should help.

Washington State University Extension’s HortSense website recommends:

Avoid injuring plants to reduce possibility of infection.
Avoid overhead irrigation.
Maintain proper plant nutrition. Healthy plants resist disease better.
Plant disease-resistant species such as Syringa perkinensis, S. microphylla, or S. vulgaris vars. ‘Alphonse Lavallec’, ‘Crepuscule’, ‘Floreal’, ‘Guinevere’, ‘Jeanne d’Art’, ‘Lutece’, ‘Maud Notcutt’, ‘Mrs. W.W. Marshall’, ‘Rutilant’, or ‘William Robinson’.
Prune and destroy infected tissues as soon as they are noticed.
Space plants properly and prune to provide good air circulation. This will slow down spread of the disease.

Here is more information from University of California, Davis’s
Integrated Pest Management site. Excerpt:

“Bacterial blight is promoted by prolonged rainy springs. Symptoms may be
more extensive in wetter areas. Prune branches showing dieback and severe
blight. Space plants to provide good air circulation. Prune during the
dry season when infection is less likely to occur. Do not wet foliage
with overhead irrigation; do not overfertilize. Small plants can be
protected to some degree by keeping them covered by plastic (or moved
under plastic). Plant resistant species if available. If the disease is
systemic or cankers appear on the trunk, the tree will probably die and
should be removed. If the disease is confined to leaves, damage is not
usually serious and trees normally recover. Sprays do not give reliable
control.”

observations on earthworms

So, here is a weird one for you. I was out in my garden this weekend and I noticed that the dirt paths that I had raked of leaves (but still had a few leaves around) all had small piles of decaying leaves. There were lots of these piles, measuring about 3-5 inches in diameter. When I pushed the leaves aside, I found a small half-inch hole under every single pile. When I dug into the hole, the only thing I found was an earthworm, which occurred in every one. I did not see this on the paths that I had not raked that still had lots of leaves, nor in the garden beds, most of which are heavily mulched with cedar chips.

I know earthworms are major decomposers of decaying leaves and that they mix the organic matter down into the soil. But do they gather the leaves into little bunches? How the heck do they do that?

I know earthworms go out onto the surface at night, grab a leaf or two and bring them back to their hole. I have witnessed this personally in my own garden (usually pathways or nearby).

But why and how?!

The book you need to read is The Earth Moved: On the Remarkable Achievements of Earthworms by Amy Stewart (Algonquin Books, 2004). It is one of those nonfiction books that is written with attention to prose, so I could not find a quick answer, but I am sure it is in there.

Other staff have also observed this, so it is not rare. It seems to be the nightcrawlers that do it. Go out at night with a flashlight to see for yourself.