Horticulture Guy

Q. I have a 6-foot laurel hedge, which is about 35 years old. Over the past year, the leaves in various areas of the hedge have suffered from a fungal/mildew problem. On advice from a local gardening specialist, I sprayed the leaves with something they recommended. This temporarily alleviated the problem but over the weekend when I was clearing out the plants around the hedge, I noticed that there were a lot of leaves lying under and along the base of the hedge.  When these were all cleared out, it became apparent that some of the branches at the bottom were rotten through. They didn’t even need to be cut, they just snapped, despite being very thick. It now seems that the stems with this problem are the ones which have all the diseased leaves - hence the randomness of the leaf problem. All growth for about 2 foot from the bottom has now been cleared and the worst of the rotten wood removed. The majority of the hedge is healthy but it now has some gaps! Will the whole hedge die? Given that it is November and the onset of winter, it wasn’t a good time to prune it, but I thought it would be better than leaving it. The base is now clear and air can circulate. I live on a very busy, noisy road so can’t be without my hedge as it provides a vital sound and privacy barrier. Should I take it all out and replace it with the largest replacements I can buy or should I leave it and see if it survives and grows back? Your help/advice would be much appreciated as, due to the time of year, time is of the essence! Charmaine - United Kingdom Many thanks.

A. Although English Laurel (I assume it is English since you are from the UK and probably don’t call it English Laurel there) is quite disease resistant wet conditions can create conditions ripe for bacterial and fungal infections.  In this case it was probably one of the rotting pathogens like Fusarium, Rhizoctonia, or Pythium.  These can attack both roots and stems.  Your instincts were good, as cleaning diseased wood should be done as soon as you find it.  The key is to cut back into clean disease free wood if possible and clean your pruning equipment between each cut to prevent spreading the disease.  These Shrubs are very resilient but you will need to address the air circulation and also determine if the soil stays overly wet which will exacerbate the situation.  I would see how it fares over the winter.  You may see new growth from the root system.  In the future in addition to normal hedging (which concentrates the growth decreasing air circulation) you may also want to do some modest thinning. Let me know how things progress.

-- HG

Q. Peter, I dug up irises from a bed over-run with grass, with a grand plan for making a raised bed lined with landscape cloth to keep the grass out, but what in the world should I do to keep the irises alive until hubby makes that bed for me? Keep them- not him- out in the air? Stick them in perlite? Plant them somewhere else for a while? Have I killed them? They have been out of the ground for 5 days. Sure would appreciate your words of wisdom. Many thanks! Linda S. - Lakewood, WA

A.   Yes you should plant them somewhere else for a while.  This is called “heeling them in”.  You simply dig a trench in another section of the garden and line them up in the trench at about their same growing level in the grass infested bed and cover with soil until you are ready to put them back in the reclaimed bed. Water them in the unlikely event there is no rainfall.

-- HG

Q. I own a Dracaena Mass Cane.  It stays indoors in the winter and is brought out in a screen house in the summer months.  It enjoys being outside so much that it now is taller than ceiling height of the house. Question: Can the top be cut back?  It is about 9 ft. tall now.  If I cut it back to say 4 ft. will this kill the tree?  Is there a certain time of the year this should be done? Tony R. - Valley Stream, NY

A.   Yes in theory the canes can be cut back on Mass Cane (Dracaena fragrans ‘Massangeana’) since the plant you now own came from a stem cutting taken from a mother plant.  So in theory you should be able to remove the stem and have new growth form below the cuts.  In theory you could also put rooting powder on the revomed stems, or sections of those stems and start new plants (stripping the leaves off of them when they are removed.  In tropical regions like Costa Rica where they are harvested I believe they propagate all year.  But in NY I would wait until the weather is a little closer to “tropical” and do it in the spring the late spring or early summer.  I have never performed this operation on a Mass Cane myself so this is all theoretical.  Since most plants have multiple canes I would suggest testing one cane this summer and see how it responds.  If you get new growth then you can comfortably prune back the other canes. 

-- HG

Q. We have an old, large maple tree in our yard.  It does not have as many leaves as it used to.  It appears to be slowly dying.  Many years ago we put a raised rock bed around the tree and planted a few items.  The dirt is about one foot high.  Could that have been distressing the tree over the years?  We plan to knock the rockery bed out and take the excess dirt away.  We’ve also had woodpeckers creating sap drips and wondered if they were causing the problem.  Do you think we can save the tree by taking the dirt away?  Or is it too late?  Thanks, Jan - Tacoma, WA

A.  Yes I believe the raised bed around the tree is exactly why you are seeing a decline in the Maple.  Changes in soil level above trees roots reduce oxygen levels for the root system effectively suffocating the tree.  If the root surface area is large enough will completely kill a tree very quickly.  If the tree still shows signs of life removing the excess dirt may allow the Maple to recover.  The woodpeckers are likely a symptom and not the cause of the Maple tree’s decline.  

-- HG

Q. We have a Small Leaf Linden tree at our curbside.  It is quite large. 10 years ago, when it was pruned, the leader was cut.  Since then, it has grown into a very huge, very full mushroom shape. 3 years ago, we had it pruned by an expert. Wonderful job.  However, all summer long, small dead branches kept falling off into our driveway.  It is overgrown again and must be pruned again. Hubby wants it pruned and cut way back on the sides and top to make it smaller.  Please advise us for the best time of the year to have it pruned.  Thank you. G. Davis - Philadelphia, PA

A.  With the loss of the leader you now have a large shrub on a trunk.  I am not sure if the person you had prune the tree mentioned about trying to retrain another branch to become a leader and give the tree back its pyramidal shape. This is not essential in this case since the Little Leaf Linden (Tila cordata) can be pruned like a hedge.  Lindens have a tendency to bleed sap if pruned around its growth spurt in spring so avoid late winter through spring for pruning.

-- HG

Q. I would like to start some emerald green arborvitae from cuttings this fall. What steps should I take to ensure successful propagation? Thank you. Mark Bruser - Tacoma, WA

A. Cuttings for Arborvitaes (Thuja) can be taken from summer to mid fall and should not be fully ripe but rather semi-ripe. Although you can try now with ripe wood but you should use rooting powder to aid in root formation. The cutting taken should be from current season’s growth but should also include a sliver (or heel) from the older wood to aid in rooting. This is called a heel cutting and is usually achieved by pulling the cutting from the main stem sideways thus removing some of the bark. Place the cuttings in a well-aerated mix of half Perlite (or pumice) and half peat moss (or coco peat ) which has been moistened. Place the cuttings in a plastic bag or humidome monitoring the moisture levels. A heat mat is also beneficial as it speeds up the rooting process.

-- HG

Q. I have a 10-year-old camellia tree that is growing out of control. It is located in the West corner of the house and gets a lot of western sun.  I trimmed just the top last year and this year cut back to the trunk some of the lower branches.  It is located next to my dining room window and don’t want it to block the view completely.  It blooms greatly.  How much can I trim it back and when?  Do I have to trim it every year since it seems to like my trimming? Thank you, Patricia Stolp - Spanaway, WA

A. Well I don’t know how big your dining room window is but your camellia will be wanting to be a minimum of 8 feet tall and a little more than half as wide.  That is a minimum.  So you may need to cut it back yearly to keep a view out of your window.  Fortunately they are generally respond well to heavy pruning - rarely dying back from it.  If you don’t want to loose blooms then prune them just after they finish blooming.  Make what are called heading cuts (removing part of the limb) back into the interior of the shrub.  Or when necessary you can perform thinning cuts as you did on the lower branches where the entire branch is removed. 

-- HG

Q. We just moved into a new house. There are several existing fruit trees, most of them are damaged looking. I don’t think they had much water or care prior to us. Will simply watering and fertilizing bring them back or?  Mick Davis (Member)- Tacoma Washington (Spanway area)

A. Regular watering and fertilization will definately help but I would also recommend some judicious pruning. You can download a free Adobe Acrobat (.pdf) file from the Extension website called Training and Pruning Your Home Orchard. This would be a great resource to get you started.

-- HG

Q. Is there a local source to buy trees? We would like to use Pines and Firs to complement the natural trees. Mick Davis (Member) - Tacoma Washington

A. If you are looking for small quantities of native firs and pines then looking up local nurseries in your yellow pages is an option. You can also find specialty nurseries like Woodbrook Nursery in Gig Harbor. Or you can go to a Washinton Native Plant Society Plant Sale. There is one coming up in this month up in Seattle (October 14th, 2006). If you are interested in larger quantities (at least 100 of a species) then you may consider Webster Forest Nursery in Olympia.

-- HG

Q. We have a fir tree that has vines growing up it. Is this damaging to the tree? Mick Davis (Member) - Tacoma Washington (Spanway area)

A. It is very likely that you have English Ivy (Hedera helix) growing up your Fir trees.  It is very invasive in the Pacific Northwest.  The potential damage is two fold.  First the evergreen vines of the English Ivy will increase the wind resistance of the tree making it more vulnerable to blow overs as can often happen during our winter windstorms.  Second if the tree is small enough the ivy can get up to the crown and smother the tree.  This is not as common in Douglas Fir (due to their growth rate) but it can happen in many other trees. The Ivy does not attack the tree directly and the attaching structures do not penetrate the bark of the tree.  I always recommend the removal of Ivy from trees.   

-- HG