Horticulture Guy

Q. I would like to know which chemicals can be mixed and sprayed by on the homeowner/gardener and will react to new or reused concrete to act as a permanent natural looking tint. Many years ago I saw it on TV used in a wonderful California designer garden and I want to try this out with a friend. As I recall it was safe to animals and plants and could be put together with chemicals purchased from the local hardware or garden center. It was cheap and a good solution to gray chunks of ugly cement. Hope that you can help! Carol Williams, Gig Harbor, WA

A. I am not familiar with what you saw on TV but it is very possible that the segment you saw made the process of cement staining easier than it really is.  Existing concrete must be acid washed, and then the acid must be neutralized.  The surface must be free of contaminants like oil stains, dust etc. since the concrete stain actually reacts chemically with the concrete in order to change the color.  Anything that gets in the way of the reaction can cause irregular staining patterns. If you are very meticulous and you follow instructions well you may be able to do this yourself, but there is a lot of room for error when staining concrete.  The necessary products may be found at your local hardware and garden centers but you may consider have a professional do it for you since they have more experience with the process. 

-- HG

Q. Our lawn–For the most past, it is way too thick. Even the front, which was resodded not too long ago, is a jumble of roots. We thatch every year–had it professionally done last year–and of course fertilize and water. Will using an aerator help? Any suggestions will be appreciated as we are disappointed that it doesn’t show all the time and effort that is expended on it. Thank you much– Judy Payne - Puyallup, Wa

PS. Also a schedule for lawn maintenance would be helpful.

A. From your description and the fact that you are thatching each year I will assume that your thatch layer grows deeper than ½ inch. An ½ to ¾ inch layer of thatch is desirable as it protects the root system from foot traffic and keeps the roots cool in the summer. Any more than this then you develop the “thatch roof syndrome” where water and air do not penetrate the layer. Thatch is made primarily of stems and some surface roots. Contrary to popular belief the blades of grass do not contribute significantly to thatch development so mulch mowing (allowing the grass clippings to return to the turf rather than removing them in a mower bag) is not a causal factor. Using an aerator (core aeration is preferable) would be useful if the thatch layer is more than 2 inches thick. A longer-term solution is to determine which contributing factors are present in you lawn and correct them if possible. Bentgrasses (colonial) and Kentucky bluegrass tend to have a propensity to form thatch more than other grasses. The way you mow can also influence thatch development. If you regularly allow the grass to grow long between mowings or maintain the grass above the appropriate height for the type of grass you grow you can contribute to thatch development. This is because the grass stems can move up from the soil line where microorganisms can break them down. In a healthy thatch appropriate lawn there is a balance between thatch development and breakdown. So if you over fertilize the lawn with nitrogen you can throw the balance in favor of the thatch. In addition too little nitrogen (necessary for many decomposing organisms) can also slow down breakdown of the thatch. Low pH (optimal is 6.5 to 7) can also inhibit decomposition of thatch. Check your lawn for fertility and pH (soil tests) and adjust appropriately. Hopefully there are some practices you can change to treat the cause of the thatch buildup and reduce the amount of thatching your lawn will need which is treating the symptom. My website’s Garden Calendar Planner has a month-to-month tasks for the garden. The Landscape Tasks section may satisfy your need for a lawn maintenance schedule since it lists the major lawn tasks.

-- HG

Q. I have a few gravel areas around my house and part of my driveway is gravel as well. Every year I need to apply some sort of vegetation killer to prevent the grass, dandelions, etc. from going crazy. I seem to remember reading in your column about some sort of organic herbicide that was a by-product of the wine making process. It lowered (?) the pH level of the soil so nothing would grow for quite some time. This sounds appealing to me and would appreciate any info you may have as to it’s use and availability. Thanks. Buck Nieraeth - Tacoma, WA
A. Back in 2001 a product called Blackberry & Brush Block came out.  Acetic acid, which was one of the main ingredients, is a byproduct of the wine industry in the sense that all wine contains trace amounts of acetic acid, and it increases when the wine goes “bad” and become vinegar if not stored properly.  Vinegar that we buy in the store is about 5% acetic acid.  The initial claims of the Blackberry & Brush Block discussed the fact that it could be used to reduce the soil pH to 3. In theory a soil with a pH of 3 would be very inhospitable to many forms of life including plants.  Researchers at WSU extension questioned this mode of action. They sited that the acidity of the product was not strong enough to achieve this pH (when using reasonable amounts) because of the inherent buffering capacity of most soils.  I agreed with their analysis and stopped recommending this product for use in this “soil pH” mode of action.  Acetic acid can also be used as a contact herbicide. Early research indicated good control of annual weeds and less consistent control of perennial weeds, which may need multiple applications. You may find that your current control methods are as good or possibly better than those you might get with acetic acid based herbicides.  It all depends on the weeds you are trying to control.  For example, dandelions would likely need multiple applications because of its storage taproot that will not be killed by the acetic acid based herbicide. 

-- HG

Q. I believe I have crustose growing on my rock pillar columns (white crytal like hairs) how do I kill it? Terry Johnson - Lacey, WA

A. I believe you are describing crustose lichen.  Lichens are a symbiotic organism that pairs up a species of algae (or cyanobacteria) and a species of fungus.  The various combinations make up the different types of lichen.  These lichen grow in a very thin layer on all kinds of surfaces including tree trunks, boulders, rocks, as well as statues, columns and pillars (as is in your case).  This is in contrast to the fruticose lichen, which are branching and often hang off of their substrate.  Fruticose lichens are usually an indicator of air pollution since many varieties die off when exposed, but the crustose lichen is more resistant than other types of lichen.  The crustose lichen is of particular concern to conservators of stonework and statues since the structures that hold the lichen to the surface are small enough to get into small cracks and fissures and eventually cause some deterioration.  Their metabolic processes can also create acidic conditions, which can be detrimental to many types of stonework. This is a gradual process but when you are a conservator you are thinking about long-term preservation.  I know that copper sulfate is effective on lichen but it can stain some kinds of stonework.  There are other treatments of which I would be hesitant to recommend to a do-it-yourself homeowner.  The other issue is that even if you kill off the existing crustose algae and clean them off this does not change the conditions that will allow future growth from re-colonization. There are often treatments that can protect the stone from future attacks like coating them in epoxy resins.  I would suggest hiring a professional that works in this area to help you with your specific situation.

-- HG

Q. My friend Dave has three yew shrubs alongside his porch.  They are over 4 feet tall and almost as wide.  I have offered to help him get them under control but I want to be sure that if I prune them back hard they will come back.  I understand that conifers may not get new growth when they are cut back too severely.  Thanks, Ron Lewis – University Place, WA

A. Hello Ron.  You are right that most conifers do not respond well to heavy pruning to control their growth. This is because there is little to no new growth that will form on older wood.  Only new growth (current season) reliably will send out new growth.  This is why only light pruning is recommended and thinning pruning that does not have the intent of forming new growth.   The Yew (Taxus spp.) is an exception to this rule and latent buds in older growth will break when released by pruning cuts above them.  The yews (and the yew family) are also exceptions in other ways from the conifers whose name implies cone bearing.  The yew instead of bearing multiple seeds in a cone bears a single seed inside a pseudo-fruit. The pseudo fruit forms from the tissue where the seed attaches to the plant rather than from the any reproductive tissue (ripening ovary) as in most true fruits.  This pseudo-fruit forms the distinctive cup around the seed.  Now back to pruning the yew.  Most likely the yew was sheared which keeps the yew rounded but doesn’t control its size very well.  As you are suggesting deeper cuts are necessary since surface-heading cuts will only promote growth just behind the cuts.  You should determine where the new perimeter of the shrub will be and then hand prune branches back inside this perimeter.  Also look for multiple leaders that may have formed from the shearing and reduce them to a single leader especially if you would like the shrub taller than wide.  Remove any branches that grow back into the center of the tree. Also make sure the top of the tree is narrower than the bottom to allow for good light penetration. 

-- HG

Q. When is it time to prune our lacecap hydrandeas?  It’s hard to find information on the proper pruning techniques. Thank You Jan Cook - Lakewood, WA

A. I just had the same question about hydrangeas this past week from my friend Rosel at the Lakewood YMCA so it looks like the sun this past week has worked its magic and has people out in their gardens again. Lacecap / Mophead Hydrangeas (Hydrangea macrophyllus) and Oakleaf Hydrangeas bloom on old wood and therefore should not be pruned after late summer if you want to keep all the flower buds.  Wait until after it blooms. On the other hand the PeeGee Hydrangeas (H. paniculata) and the Smooth Hydrangeas (H. arborescens) form flower buds on new wood and can be pruned in the fall winter or early spring without the removal of pre-existing flower buds. Knowing which type of hydrangea you have is critical to determining when to prune them.  Hopefully you remember or kept the tags of your hydrangeas so you can choose the proper time for pruning.

-- HG

Q. Every couple of years or so I get attacked by moles. None of the surrounding yards get any but they love my place.  They have stayed away the past two to three years but they are returning with a vengeance. In the past I have tried various things to rid my yard of them. Poisons, traps, etc…I never know if one works or not, and they stay for a very long time anyway. Please give me some practical advice on how to make them go away. My yard has many fir trees in it, and lots of shade, which brings me to my next concern.  The past two years I have notice round holes and falling bark from three of my fir trees in the back yard…. In the 35 years I have lived here, I have wrestled with carpenter and moisture ants. well, all kinds of ants!! I spray the trees two to three times a year and even had them professionally treated and sprayed for four years. Also the house.  I am worried about the health of the trees now and have had some Tree Guys out to estimate limb removal and thinning and was told that they are healthy other than for some beetles that are in side the tree and that woodpeckers are eating the bugs and making the holes. That was not exactly comforting to me. I worry that the inside of the trees are being eaten away and will weaken and fall. Also it is curious to me why they just appeared two years ago. Other than having the trees taken down, can you advise me what to do.  Margi Fishbaugh - Lakewood, WA

A. The moles “attack” your yard because it is providing them with a food source.  They are predominantly insectivores feeding on beetles, grubs, and other insect larvae as well as earthworms.  The moles will either leave when the food supply is exhausted or if there is something in the environment that suitably discourages them from feeding there.  Eventually they come back again when the food source builds up again or the nuisance is gone. This is the reason for the cyclical nature of your mole problem.  I am sorry to say that total control is very difficult. There are many ways to control individuals including repelling, poisoning and trapping but if you don’t get rid of the whole local population then the issue can reoccur as you have seen.  A good explanation of our local moles is available from the county extension:

http://cru.cahe.wsu.edu/CEPublications/eb1028/eb1028.html

I generally recommend controlling grubs and other insect larvae (if you find they are present) in the soil using organic methods and therefore reduce their food source and therefore the damage.  Again this does not guarantee complete control.  As far as your trees are concerned if you did your homework in selecting your “Tree Guys” and they are certified professionals then their advice would be sound.  If they say your trees are healthy and not hazards then I would trust them. If you are not sure if they are certified ask if they have ISA (International Society of Arborists) certification.  Or you can check yourself (or select one) by using The ISA’s website search function:

http://www.isa-arbor.com/findArborist/findarborist.aspx

The fact that woodpeckers are feeding on the beetles means they are also keeping the tree pest free and healthy.  They are much more persistent than you could ever be in a spraying program. 

-- HG

Q. Hi - I have had a Christmas cactus for about 2 years now.  Its leaves are now getting about 12 inches long, and very heavy.  Am I watering it too much?  I water it twice a week.  Also, I recently added coffee grounds to help it.  Not sure I should have done this.  HELP! Candice Zoot – Denver, CO
                                                                                                                    
A. The size of your plant is not an indication that you are overwatering your plant.  How much you water depends on the preference of the plant you are growing and the conditions in which it is growing.  Christmas cacti are epiphytic so instead of living on the ground in a desert, lives in the crotch of a tree in a jungle just like orchids.  But like its other cacti relatives they have evolved to live in challenging water environments.  The desert simply provides little rainfall.  Although jungle evironments are much wetter the crotch of a tree doesn’t give the root system much to work with as far as water holding capacity.  So the plants have adapted periodic dry conditions.  I suggest using your finger and feeling the top two inches of the soil and when this has become moderately dry water again.  This may work out to be twice a week as you have been doing all along.  Overwatering of Christmas cactus often results in the root and/or stem rotting.  Coffee grounds are a fine addition of organic matter container but they also can reduce the pH of the soil (which is not necessarily bad but it is good to know).  Too much around the stems of the plant may retain water around the stems so keep the layer thin.  Christmas cacti also prefer a lighter soil mix that has good drainage. 

-- HG