Horticulture Guy

Q. I am working on a mostly native garden at our property in Mason County, WA and I am trying to locate some CA Bay Laurel trees/shrubs to plant in fairly deep shaded areas. Do you have any suggestions as where I might look for these plants? Thanks for your help, Bernie Perez - Tacoma, WA

A. I guess the key to your question is “mostly native”.  California Bay Laurel (Umbellularia californica) is only found natively in California and Oregon.  It does grow in the warmth of the Puget Sound, but I am doubtful any native plant nurseries will carry it since it is not native. You may find it at some of the larger garden centers in the area but there is no guarantee.  I would call ahead to be sure.  If you don’t need the plants to be too big you can also get them through mail order.  One large grower I know in Oregon where the plants are native is Forest Farm in Williams, Oregon (http://forestfarm.com/). They grow them from seed in grow-tubes and the plants average about 6-18 inches in height. 

-- HG

Q.  I want to plant Pampas Grass along a fence line. We have problems with our neighbor’s horses eating any plants we plant. We do not want to close our property in with a fence, so we are looking for vegetation that will help.  Will horses eat Pampas Grass?  Any help you can give will be appreciated.   Thanks… Farley Dodson - Pensacola, Florida
A.  Well in past questions I have warned people cutting back or dividing Pampas Grass to wear protective gear since the leaf edges are razor sharp and can cut skin (imagine getting compound paper cuts).  I think this is the reason Pampas Grass is resistant to deer browsing.  I would guess it isn’t very pleasant on the tongue either.  Now resistance does not mean deer proof and a deer is not a horse but the odds are in favor of horse resistance.  In addition I assume your neighbors feed their horses regularly.  Deer will often eat resistant plants when there is little else to eat and their option is starving.  Test one plant out to minimize your loss should my theory not hold.  Let me know how it goes.

-- HG

Q. I am a landscape architect working on a new building in Los Angeles. The owner wants to put bamboo such as Bambusa vulgaris in the lobby, which has 25′ glass windows on 2 sides and 10 foot-candles of light from the ceiling. What type of additional lighting would you recommend for the bamboo and how many additional foot-candles? Thanks, Claudia Kath - Laguna Beach, Ca

A. I would recommend 1500 foot-candles. This is the equivalent of the light a plant would get sitting in a south facing bay window.  I would suggest Metal Halide lamps as your additional lighting source since their spectrum is the closest to natural sunlight.  You will have to work out the calculations for how many watts you will need since the distance the lamps are from the plants will determine it.

-- HG

Q.  One of our vine maples has some sort of jelly-like, slimy stuff (like small jelly fish found dead on a beach!) on the ground around the roots. What might that be? We too are having different success with vine maples on different parts of our land, and are grateful for your suggestion in a past column to talk with an arborist.  Thanks.  Audra Adelberger - Seattle, WA

A. Well if you had said the slimy stuff looked like vomit then I would have been fairly certain that what you are seeing is slime mold.  Many a dog has been blamed for what was really slime mold.  But the small jellyfish dead on a beach is a little harder to determine but it is still quite possible.  Slime molds are an interesting group of organisms. Their actual relationship to fungi or protozoa has been debated over the years in the scientific community.  Many of its structures look like fungi, but it also has a motile (visibly mobile) stage, which makes it seem like an animal.  I couldn’t do the slime mold justice in the space I have so if you have an interest you can do a search on the Internet to get more info and pictures.  They feed on dead organic as well as protozoa, fungi and bacteria. The location under your vine maples is not likely a cause for concern; it may just be using the mulch below the tree as food.  You may consider getting some expert help at the Puget Sound Mycological Society’s 42nd Annual Wild Mushroom Show this weekend at the Sand Point Magnusson Park in Seattle   (Saturday from noon to 7pm and Sunday 10am to 5pm).  There will be experts on hand to identify mushrooms for the general public.  Of course you should bring a sample with you. For more information or directions see their website http://www.psms.org/exhibit.html

-- HG

Q. When our tree first blossomed and started leafing out, we thought it was an apple tree.  The fruit started developing but looked a bit odd for apples.  Finally found out it was an Asian Pear. Last fall the waterspouts and crossover limbs were removed. There were lots of blossoms but little fruit this year. How and when should pruning be done?  Can the suckers on an Asian pear be used to start a new tree? Carol Weston - Roy, WA

A.  That is an easy mistake to make since another common name is the apple pear.  This is because the fruit have the round shape (more specifically the Chinese variety of pears - Japanese can be more “pear shaped”) of an apple and some of the nice crunch as well.  But as you noticed the skins are not as smooth and are tan in color. There is pruning that can be done both in the winter and early summer.  Winter pruning will remove flower buds that formed over the summer and early fall.  Summer pruning is for cutting back the ends of new growth to keep them in check and winter is for correcting structural problems, cutting back the leader or thinning out overlapping fruiting spurs.  Watersprouts and crossing limbs can be pruned winter or summer. Please learn from my mistake.  I waited for several years for my four-way (4 cultivars grafted on one tree) Asian Pear tree to start producing.  The flowering was great each year but for two years I only had about 4-6 pears.  I started training the limbs to grow laterally (this promotes fruit setting) and then I had a bumper crop.  I came out one sunny August day to find that a whole limb had pulled away from the trunk.  The tree had produced more fruit than it could handle.  The next year the tree set two fruit.  I should have known better but my gluttony got the better of me.  The moral of the story is to thin the developing fruit out early in the spring so that there are no more than 1 fruit for every six inches of branch. This will also prevent the heavy and light crop cycle. You can download a free Adobe Acrobat (.pdf) file from the Extension website called Training and Pruning Your Home Orchard: http://cru84.cahe.wsu.edu/cgi-bin/pubs/PNW0400.html
Although it is possible pears are not easily rooted.  Grafting or budding onto a specific rootstock is the common propagation method for pears and other fruit trees.  The rootstock is used to impart some favorable qualities to the tree like controlling the size of the tree, providing tolerance to certain soil conditions and early fruiting.  If you did manage to root a water sprout the plants would likely become much larger than the tree you have and take much longer to start setting fruit.

-- HG

Q. How do you propagate Dizygotheca elegantissima and will it branch if the tip is snipped? Nancy Bandusena - Kota Kinabalu, Malaysia

A. Well I am sure where you live you can grow the False Aralia (D. elegantissima) as an outdoor landscape plant since you are in a tropical climate but here in the Pacific Northwest we know it as a house or sunroom plant. The False Aralia had a heyday during the Victorian era as a conservatory plant. It has since been used occasionally in indoor landscaping and as a houseplant. Despite being having beautiful light and airy foliage with coppery cast this plant is finicky when it comes to warmth and humidity. Lack of warmth and humidity will cause the lower leaves to drop. This detracts from their inherent beauty. The False Aralia is reluctant to branch even when cut back so it is difficult to force new foliage below. They can be propagated by seeds (if your plant produces any) cuttings, and air layering. So if a plant is getting leggy you could air layer the plants (making a cut part way through the stem, putting rooting powder, wrapping inside the wound and outside with moist sphagnum moss and then wrap with plastic) to shorten up the plant. Once roots have formed you can cut below the layer and replant all the cuttings. Or Take cuttings using BONTONE ROOTING POWDER..

-- HG

Q. In the past 6 or 7 years, a blue-flowering weed has overtaken parts of this neighborhood, and it is highly aggressive. It thrives in shade. It has 8″ (more or less) tapered basal leaves. The flower stalks are round, from 18″ to 3′ or 4′ tall, and branch at the tips into clusters of small half-inch bright blue blowers with white centers. The leaves and stacks have a fuzzy feel. Seed production is prolific, and the roots send out stolons. The mother root develops a thick white fleshy vertical rhizome-like form as much as 1′ deep. After blooming, the plant quickly turns into a grey mildewed mess. The fuzz and the after-bloom mess remind me of mertensia. What is this? How can it be controlled without chemicals? I cut the flowerheads before seed forms, and dig as much of the root as possible. Beverly Isenson - Steilacoom, WA

A. I have these in my yard as well. They are botanically Pentaglottis sempervirens. Common names include pentaglottis, evergreen bugloss, alkanet, and green alkanet. It has become a weed in many parts of the world (native to France) because the roots were used to make red dye. The actions you have taken so far are the non-chemical controls of this plant. Depending where the weed is you can dig them back and then put down a weed fabric barrier. I have found that the “mother root” as you call it will go much deeper than 1″ as you indicated. These fleshy storage roots break easily. If you don’t get the entire root you will get re-sprouts. I have seen re-sprouts from root fragments as deep as nine inches. So make sure you are using a weeding tool that can get deep down along side the root like a STAINLESS STEEL DIGGIT WEEDING TOOL or a STAINLESS STEEL HORI HORI KNIFE . You can also spray with a glyphosate based herbicide.

-- HG

Q.  I have 3 large pampas grass that I would like to trim as far down as I can. The middle of all of them is old, dead remnants of previous years. How far down should I cut it and is now a good time to do that?  Thanks, Sydna Lefebvre - Tacoma, WA

A. Because of our mild winters we can cut back pampas grass in the fall or in the spring.  The tops of grass are usually left in place over winter for their interest in the landscape and as protection against cold weather.  If you like the look of the plant and don’t need to remove it now then wait until spring.  If you do want to cut it down now I would cut it down to about two feet and then again in the spring as close as you can get to the ground without cutting into the new growth. This will protect the plants crown in the event our winter isn’t as mild as usual.  Just like lawn grasses the active growing points of ornamental grasses like pampas grass are at the soil line.  Wear long sleeves, pants and gloves (some people wear goggles too) since the leave edges can scratch and cut exposed skin (and corneas). 

-- HG

Q. I had three Black Locust trees removed but now sprouts are growing from the extensive root system.  Is there a way to eliminate the problem?? Also, there is one 50ft tree on the property.  I was wondering when and how do I trim it?  Thank You Rich Brown - Tacoma, WA

A. You are facing an uphill battle against the disposition of the Black Locust tree.  Although many plants can send up root suckers from shallow roots that have been injured (e.g. by a mower blade) Black Locust produces suckers without provocation.  This is because the tree uses this as mode of reproduction. This allows the trees to make dense stands that crowd out competing plants.   So there is little chance you can eliminate the problem from the living tree.  Instead you may try to mitigate the problem using a product I mentioned about 3 months a go called Tre-Hold.  This is a plant hormone based spray that inhibits suckers both above and belowground.  A certified professional with proper licensing will be able to advise you on the timing of the spray(s).  A professional should apply this because any drift of the hormone spray can affect non-target plants. Now as far as the trees that were removed you can either keep the sprouts cut down regularly and roots will exhaust themselves eventually or you can have a professional apply a non-selective herbicide to the fresh re-growth so that it will kill the root system. 

-- HG

Q. Are Oakleaf hydrangeas always brittle? I have had two episodes of severe breakage, once when the entire plant broke off at the soil line as I was planting it, and I am not a careless or inexperienced gardener. Please give me a description of the durability of this shrub. Otherwise it sounds like a good garden choice. Gretchen Russell - Gig Harbor, WA

A. From my experience I have not found Oakleaf Hydrangeas (Hydrangea quercifolia) to be particularly brittle. It is a great garden plant that is fairly pest free and as you say a “good garden choice”. Sometimes damage can occur to a shrub when it is being removed from the pot. If the plant is root bound or tight in the pot there is a tendency to want to tug the shrub up and out holding the branches and pushing the pot down with the other hand. It is better to tilt the shrub on its side (when possible) and roll on the pot with your palms to loosen the soil in the pot and then slide the plant off. If you can’t turn it then massage it between your two palms or tap the sides. Still tilt the plant towards the ground to slide it out. This reduces the force of gravity from the root system as you remove the shrub. Then the plant can be handled by the rootball when it is planted. - HG

-- HG