Horticulture Guy

Q. Dear Peter, 1. the local Starbucks store saves coffee grounds for gardeners like us. I know that Blueberries and Roses like acidic soil. What other fruits, vegetables and flowers thrive in soil made acidic with coffee grounds? 2. One of our Rhodies died due to a disease of some sort. Is it a bad idea to plant another Rhodie in the same spot? If not, is there some thing that we can treat the soil with there before planting another Rhodie? Is there a period that we need to wait before safely replanting another Rhodie there? Bill and Sue Spencer – Fox Island, WA

A. Coffee grounds are a great addition to the garden as a side dressing for plants or even into the compost pile providing nutrients (roughly 2 percent nitrogen and potash and a small amount of phosphorus) and humus. There is research that indicates a dressing of coffee grounds around the base of plants can reduce slug damage. Although coffee grounds will contribute to soil acidity, one teaspoon of lime or wood ash is all that is needed to neutralize each five pounds of grounds. Most conifers prefer acidic soil as do rhododendrons, azaleas, heathers, beech and oak trees. For veggies good candidates would be potatoes (helps reduce scab), sweet potatoes, radishes, parsley and peppers to name a few. Most plants have a range of soil pH that they will grow successfully in. So it is a good practice to monitor you soil pH each year and make adjustments as needed to keep the soil in the optimal range for the plants you are growing. The coffee grounds will not immediately impact the soil pH since much of the acidity results from the decomposition of the grounds by certain acidifying bacteria. If your rhododendron died from a soil borne disease it would not be prudent to plant rhododendron or azaleas in this spot again. It is important to determine the cause of the disease (the County Extension may be able to help) since some soil borne diseases may also prevent you from growing other species of plants that are also susceptible to the disease. Many soil borne diseases can remain dormant for years determining the disease and planting a resistant species is very important.

-- HG

Q. Peter, we live at Harvest Gate in Puyallup in the Summit area where the underlying soil is clay and very rocky. I believe you recommended as an excellent soil builder a compost mixture that will sit over the winter months. My question: when, how much and is there a product that you could recommend? Phyllis Salisbury – Puyallup, WA

A. What can happen in developments where major topographic changes are made (with large machinery) subsoil is brought much closer to the surface. This can sometimes even expose glacially compacted subsoil, which is like an impenetrable “hardpan” that goes down for feet and is a nightmare for gardeners. Normally this subsoil has at least 18 inches of soil above it but in developments there can be as little as a few inches. If the soil is hard and unworkable then setting up raised beds is the best solution. If however your soil is clay and rocky but still tillable then adding a organic matter like compost will suffice. How much and when to apply compost depends on what you are growing. If you are putting in plants this fall then apply the compost before planting. But if you don’t intend to plant until the spring then I would wait. If you just leave compost out during the winter without plant roots growing into it many of the nutrients can be leached below the root zone during our rainy winter season. Initially I would start with three-inch layer of compost and then adjust the amount added each year from one to three inches depending on the quality of the soil. I mentioned last week that Pierce County Recycled Earth Products is a good source of compost, especially if you need a large quantity. I gave out the website last week so I’ll give you the phone number (253) 798-2179 and email address pcsolidwaste@co.pierce.wa.us this week.

-- HG

Q. We have a Christmas cactus that continues to grow but rarely blooms. We have it in a garden window but it is still quite shaded. Do I need to put it in a dark room and water it for a certain period to get it to bloom? Gerri Wilson - Bonney Lake, WA

A. Christmas Cacti blooming is initiated either when they are grown for approximately eight weeks where night temperatures dip to 50-55 degrees, or when they get 13 continual hours of darkness over a period time. Providing both is a grand slam. My Christmas Cacti grow in my sunroom. During the winter months I have a heater with the thermostat set to 40 degrees. This suits the other plants I grow and allows for the cool treatment the Christmas Cacti need to bloom. So if you have a room with a window that you can leave unheated or another space this would work. Other gardeners leave their plants outside for the summer and wait to bring them inside before outside temperatures get below 35 degrees since the Christmas Cacti are not frost hardy. Once the plants have received their 8 weeks of treatment they can be placed back in their normal location and will bloom around the holiday season.

-- HG

Q. Hi Pete, My wife and I moved into a great house last year, with some fruit trees and several gardens from the original owner. i have many questions but i’ll just ask you one. i cleaned out an area on the south side of the house (it gets alot of sun too!) and very thoroughly gutted it of all the former plants and roots. i think i got rid of about 200+ lbs. of dirt as well. then i covered it with landscaping cloth to kill any weeds i may have missed. the soil is very powdery and hard to get wet. what other steps should i take over the winter to ensure a really good vegetable garden in the spring? i was thinking a couple of layers of new topsoil might be good. what do you think? Devon Haverly - Tacoma, WA

A. The most likely reason the soil is powdery and hard to wet is because you removed 200 pounds of topsoil and are now left with subsoil. Subsoil is the layer of soil below the topsoil, which is very low in organic content and has a higher concentration of fine mineral particles. This makes it more difficult to wet and a poor substrate for plants to grow in. Subsoil also erodes easily when not covered by the more biologically and physically complex topsoil. There are very few circumstances where topsoil needs to be removed or replaced. Those who regularly read my column know that I do not advocate replacing native topsoil with foreign topsoil. It is better to incorporate organic matter (like compost) to existing topsoil to improve it. I am not sure how deep you excavated and if there are any traces of topsoil left. But if you need to bring in outside topsoil to replace the topsoil you removed I suggest adding a few inches of compost since most purchased topsoil products don’t have the biological or organic matter content necessary for healthy landscapes. The handling also disrupts topsoil’s structure. You can get compost that is produced by Pierce County (Pierce County Recycled Earth Products) by the truckload.

-- HG

Q. For years we have been fighting a losing battle with an anthracnose infected dogwood. We finally decided to cut and remove it this fall. However, next to the dogwood is a mountain ash that has also been infected, but not as severe. With the removal of the dogwood, will we have better success against the infected mountain ash, or will we have to remove it also? Charles Layton - Gig Harbor, WA

A. I suspect the status of your dogwood (Cornus spp.) will not influence the heath of your mountain ash (Sorbus spp.). As far as I am aware Mountain Ash are not susceptible to the various fungi grouped under the disease complex called anthracnose. You could be misinterpreting the symptoms of a bacterial disease of Mountain Ash called Fire Blight, which is unrelated to you dogwood problem. Bring a sample of the infected areas to the WSU extension for accurate identification of your Mountain Ash problem. If it is Fire Blight then pruning out diseased areas (cutting eight inches below visibly infected tissue) will go a long way to managing this problem. Be sure to clean your pruners with rubbing alcohol between cuts to prevent spreading the disease.

-- HG

Q. Peter: Any idea what’s the matter with my front lawn? Photo’s enclosed. It is about six years old, new sod installed by Blue Sky Nursery, replacing an old lawn. They also went down about a foot/foot and ½ replacing the soil. We had an older gentleman mowing our lawn for several years and continued with his services after the installation but when he retired we changed to Blue Sky who continued to mow and trim for us. Our spraying and fertilizing is done by another company. We are getting too old to mess with lawns or even flower beds anymore but my husband waters the lawn for an hour, two/three times a week during the day hours which is less than last year when he watered every day for an hour. The spots on the photos are on the front lawn and while the older man didn’t rinse off his mower from front to back lawn, those spots weren’t there when he left. Blue Sky uses two different mowers, one for the front and one for our rear lawn (an improving scrub lawn). They maintain the spots, infestation or what ever it is could have been brought in by anyone or anything including small animals, birds or kids etc. They did replace several spaces with new sod three years ago but as you can tell, the spots returned with a vengeance. I took copies of these photos to the Master Gardens @ the WSU cooperative Extension office and they requested I bring a 4” x 2” deep sample of the lawn to them for inspection and maybe they will have a solution to the problem. I plan on doing that this week but would like your opinion. Thanks for any information. M. A. Coty – Tacoma, WA

A. Well my opinion you will receive. First off I wonder what reasoning you were given for replacing the topsoil before putting in a sod lawn. The top foot and a half is was where the most important biological components (bioactive microorganisms) of healthy soil reside. Removing the topsoil is disruptive and an unnecessary expense. It would have been more appropriate to evaluate the existing soil and amendment it for pH, fertility and organic matter. Both fast draining sandy soils and slow draining clay soils can be improved with the addition of organic matter. Furthermore there is a very good chance that the replacement topsoil was of lower quality than the soil that was removed especially when considering the bioactivity of the soil. Second I am glad your husband cut back on watering the lawn since daily watering is unnecessary and detrimental. This watering regime shallow root formation (deep roots are better) and also exacerbate disease problems. Lawns should be watered when the top 2 inches of soil dry out. The frequency and amount depends on the soil type you have but pulling back a small section of sod and looking at the soil is a good idea until you get a sense of how often to water during the dry season. Brining the sample to the extension is a very good idea. The picture you sent me would not be sufficient enough to diagnose a lawn problem. Many lawn have similar patterns- especially from a distance. I suspect it is a type of fungal disease but only with a closer inspection of the leaf blades and soil profile could the exact cause be determine. Once the extension diagnoses the problem then a treatment regimen can be implemented. There is no sure way to pinpoint where a disease came from. Fungal spores can move by wind, on mower blades, on the soles of shoes etc.

-- HG

Q. Some of our maple trees barely developed leaves at all, or bore seemingly stunted leaves this year – and now are dropping them, in August no less. There also seems to be an early “fall” on other trees, not just maple, around the area. Is this related to our extremely mild winter and possibly a freeze or two after that? Robert Payne - Edgewood, WA

A. Trees that show early fall colors and drop (senescing) in August are showing signs of stress or disease. Healthy trees take their cue to change from day length. For most trees this cue is in the middle of September. Now the fact that your maple trees barely developed leaves and some were stunted is further indication of a problem. Other trees in your area showing early color may be responding to drought stress. Past weather will only influence early senescing as far as it has influenced the general health and vigor of the trees in question. I would have a certified professional look at your trees to determine the underlying cause of the stunted leaves and early leaf drop.

-- HG

Q. Can you identify this odd looking plant? It is 8 ¾” tall. The berry look-alike seeds on the top are 1/8 to 3/8” in size. No leaves. I first noticed it last year when there was a single stalk. This year there are three stalks, several inches apart. Other plants in the immediate area are Joe Pye Weed, fern and Matricaria. This particular garden used to be filled with Canterbury bell which I dug out and planted other plants. I usually label everything but have not idea where this plant came from. Thank you, Marion Goodwin – Tacoma, WA

A. The picture appears to me to be a flower stalk of a Jack-in-the-pulpit (Arisaema spp.). Most commonly grown Jack-in-the-pulpit is native to the eastern United States (Arisaema triphyllum). I am not aware of any Northwest Native Jack-in-the-pulpits so it if I am correct in my identification of this stalk the plant either was brought in by a bird or other animal via seed or you planted it and subsequently forgot (join the club!). The distinctive flowers from which the plant gets its name appear in the early spring with just one or two leaf stalks with three leaves at the end of each. After early summer the leaves die back and the plant goes dormant leaving the solitary fruiting stalk behind. The Jack-in-the-pulpit prefers a shady woodland setting. From the plants you described growing in the area it sounds like you have at least part shade in this location. If you pull away the soil around the base of the flowering stalk you should find a round flattened tuber. This tuber gives the plant it’s other common name of “Indian Turnip” since the Eastern Native Americans used it as a food source despite the nasty calcium oxylate crystals that are sharp and unpalatable. Native Americans had many ways of processing seemingly unpalateable foodstuffs. In this case the Indian turnip was processed to extract a flour similar to arrowroot. Next spring keep an eye out for “Jack” and let me know if you find him.

-- HG

Q. I have a number of large Thunder Cloud plum trees in my yard. My rambunctious and bored puppy decided to strip the bark off one of these trees (more than 75% of the trunk). I’ve read that it’s highly unlikely this tree will survive but is there anything I can do to try and save it? The trees are now protected by wire garden fencing! Joni Fuller – Gig Harbor, WA

A. Well this certainly is not the best thing that could happen to a tree I wouldn’t give up on it yet. Since you indicated that the tree is not completely girdled which would be a complete 100% circle removed around the trunk you still have 25% conducting (water and nutrients) tissue left. Also it is possible that your puppy didn’t gnaw all the way into the heartwood below in the damaged sections. Had there been complete girdling the only option to save the tree would be to insert what are called bridge grafts to reconnect the water and nutrient conducting tissue. If there was 50% or less of girdling or the wound is narrow you can protect the wound from drying out and the cambium (the actively growing tissue that forms the xylem and phloem – water and nutrient conductors) could fill in the gap. Asphalt grafting compound is used in both a bridge graft and to protect injured areas as they heal. Bridge grafts are usually done in the spring when the bark slips easily from the heartwood. If you think the damage is sufficient enough to warrant a bridge graft then a trained professional like a certified arborist – or a professional orchardist would be the best person to work this graft. Either way protecting the wounds now with asphalt grafting compound is essential. You can find it at some garden centers and hardware stores or online. An example brand would be: TangleFoot Tree Wound & Grafting Compound.

-- HG