When Tree Roots Are Up to No Good

    Listen 00:52:56

    When tree roots grow into a sewer line it’s only a matter of time before your basement goes blahooey. On this week’s You Bet Your Garden, host Mike McGrath will explain why it’s not the fault of the tree; and how to get that flow going again. Plus answers to all your growing questions.


    Questions of the Week:

    “I purchased an older home with a 40 year old maple tree planted near the house. The previous owner told us that the sewer line had backed up due to the roots of the maple growing into the line. She said she had the pipes cleared with an auger and did not have any further problems. But I’m sure it won’t be long before those roots go back into the pipe to gain access to that ample supply of water and nitrogen. Is there anything I can do to prevent this besides flushing nasty chemicals down the toilet or cutting down the tree?”

    — Luke, who handles the books at Mulhall’s Nursery in Omaha

    Tips and tricks for tree maintenance »

    • Growing grapes

    Highlights from show for June 26, 2015:

    Growing Grass in Shade

    Richard in Hacienda Heights, CA has beautiful a St. Augustine grass lawn, over which towers a gigantic stone pine, under which his lawn won’t grow. Rich wants to know this: is there any kind of grass that can grow directly beneath a large pine tree? Mike says that there are, but not in the arid conditions of SoCal. Most often when people see a lawn struggling beneath a tree, they think it’s the shadow cast by the tree keeping that lawn from flourishing, while it’s really the root system. “Trees are bullies. They’ve evolved to dominate the world of plants.” The tree roots always eat first, and they will suck up any water they can get before the lawn can even use it. When you see your lawn browning out further and further away from the tree, it means that the tree is expanding further, sending feeder roots out to find more water, allowing it to outcompete the lawn. Additionally, if the feeder roots are a dense webbing, it will actually beat up the lawn and overtake the lawn underground. Mike recommends that Rich does what many in California have opted to do in the recent drought and allow the lawn to die. Then, switch to a system of “permeable pavers,” laying down a network of walkways that are easy to walk on like traditional pavement, but allow water through. Then, between these walkways, plant some low-growing, drought resistant plants. “I assure you that lawn does not have a chance. You can throw water and fertilizer on it from now until the end of the world and it’s not gonna help.”


    Knockout Roses

    Mimi in Wallingford, PA has three large bushes of knockout roses, on whose leaves have developed several brown spots and holes. Mike says, “When it comes to almost any plant, the problem does tend to be cultural, in that we’re doing something wrong for the plant.” But Mike also mentions that some experts believe that knockouts have been over-planted, which encourages pests and disease to develop new ways to attack them, negating some of their disease resistance. Now, Mimi sheepishly admits that she pruned her roses at the wrong time, having pruned them in the fall. Mike says that by pruning them in the fall, she’s taking the energy out of the root system, weakening them before the winter. It is better to prune them in spring, two weeks after they start growing. Mike mentions a type of scarab beetle that only comes out at night which may be the culprit, so he advises that Mimi keep her eye out for any of these bugs and he prescribes this additional course of action: remove any brown or lacy leaves from the plants. If there is a disease at work here, this can help stymy its spread, and it will also keep the knockouts looking great. It’s also a good idea to prune the bushes back this time of year to stimulate new growth.


    Clay Spray and Squirrels

    Kristine in Princeton, Nj has been having great success using clay spray to keep squirrels off of her tomatoes. She tends a vegetable and herb garden for a golf club and the kitchen staff there love to feed these squirrels scraps when they come poking about the kitchen. After this veritable feast, the squirrels then head down to the garden to have a nice light salad, presumably for digestive aid. Every day when Kris comes in to tend the garden, she finds a jumbo tomato or two, lying on the ground, with a couple of squirrely teeth marks in it. Mike says that research has found that these satan-spawn don’t even particularly like tomatoes. Some have postulated that they attack these fruits to get at the water inside, but Mike knows better: they do it because they are evil. “They know that taking a single bite out of every tomato will bring the homeowner running out in their underwear, waving brooms, and screaming and yelling and putting on a good show for all the squirrels.” Mike also notes that the clay sprays are also very effective against insects and disease, as insects don’t even like to land on the clay, and it easily washes off in the kitchen. “Now tell that kitchen staff to stop feeding the squirrels. It’s kinda like inviting anthrax to come over for dinner. What are they thinking?”


    More about Manure

    Jeff is a cattle rancher down in Northeast Oklahoma and he heard something rather strange when he tuned into the show the previous week: one of the callers insisted that the modern cattle industry today operates without the use of antibiotics and growth hormones. Mike admits that the call had completely blindsided him, as she had told him ahead of time that she wanted to talk about using manure in the garden. In that call, Mike had mentioned that at one time he had advocated cow manure as the absolute best kind of manure to use in the garden, but in recent years, he has become more and more concerned about the medications given to cows and the conditions in which they are raised. “I’m not sure that I want to use manure from an unhappy animal.” Jeff agrees, saying that his main mission in raising beef is simple: “I want you to feel good about the meat you eat, but the overwhelming majority of beef raised in this country is not raised in the conditions that most people would be comfortable with.” Jeff is a fourth generation cattle rancher trying to raise beef as antibiotic-free as possible for a company that markets antibiotic-free beef. He mentions that there is an economic premium for this kind of beef, but they are producing for such a small niche market that it’s impossible to extrapolate trends within the beef industry based upon their practices. Mike responds, “I think your market is only going to grow, and if I were in Oklahoma I’d come and get your manure.”


    Poison Ivy

    This spring, Harold from the Bronx discovered that his garden has been overrun with Poison Ivy! What can he do to get rid of it? Mike recommends that he do one of two things: either hire a professional to suit up and remove all of the vines, or do it himself. Keep in mind that chemicals have no effect on poison ivy, for although the vine is dead, the chemicals are still present in it, and once it’s dead, it appears to be an innocuous brown dead thing, posing even more of a threat. No, if Harold opts to remove it himself, here is what Mike recommends: wait until pouring rain, then either at the end of the rain or immediately after go out there with either a rolling trashcan or a big trash bag, as well as every single plastic shopping bag you can find. Wear long sleeves and long pants and be sure to wear gloves. When the plant itself and the ground around it is soaked, put these shopping bags over your hands and find where each vine meets the soil, then gently pull it out. If the soil is fully saturated, the entire root system should follow. Pull another plastic bag over it, covering the entire plant with two plastic bags you haven’t touched. Then throw that in the trash and move on to the next one with fresh bags. “I know it seems like it would take forever, but my property was totally covered with poison ivy top to bottom when we bought it, and it took me a couple weeks of working maybe twenty minutes of every third day.” He also advises to keep a hose handy, and if you think you’ve touched yourself anywhere on your body with a vine, rinse yourself off with cold water. When you go inside, keep some fresh bags on you, then immediately throw your clothes in the washer on cold, just to rinse them off, then take a cold shower, no soap, no warm water. If they re-emerge, just spray the baby plants with white vinegar. “Once you get the big plants outta there, the little baby plants are easy to control.”


    Fallen Birdseed

    Ted from Lockhaven has birdseed fallen from his feeders and he wants to know what to do with all of this fallen seed. Mike says that Ted should avoid feeding seed and should instead put in suet feeders, in order to attract carnivorous birds, and then once it starts to warm up, stop feeding them. “The birds don’t move, they already live there. They already have your children enrolled in the local schools.” Then, since these birds stick around, they eat all of the pests that would otherwise plague your garden. Mike also says that if Ted were to continue feeding seed, to keep that seed from falling to the ground, and this is important for a few reasons. Now, Ted, like most people, feeds sunflower seeds, and sunflowers, much like black walnut, contains a compound that can inhibit the growth of other plants, and so if the seed falls down, it can stunt the growth of nearby plants. For that reason, it’s also not the best material to put into a compost pile. The second reason is that any seed on the ground will attract mice, rats, and voles, as well as the evil squirrels. Therefore, Mike also recommends putting the fallen seeds back into the feeder. “It’s fun to try to get a squirrel-proof feeder to see how long it takes for them to defeat it.”


    Fertilizer Chemicals

    Kellyn in East Grand Rapids, MI recently bought a house and wants to know about the claims of an organic landscape service, and whether he needs to feed his lawn at all. Their natural fertilizer line contains bone meal, feather meal and fish emulsion and is free of harmful chemicals. Mike says that bone meal is unnecessary, as bone meal raises the phosphorous content of the soil, and most lawns don’t need any more phosphorous. The fish emulsion and feather meal promote nitrogen, making them good natural foods, but with Kellyn’s climate and considering how little sunlight his lawn actually receives, his lawn is a light-feeder. Mike also notes that lawncare companies need to come by more often than is actually necessary in order to make any money. There are a few bare, mossy spots on the lawn, which signals to Mike that the lawn is very acidic, so he recommends that Kellyn spread around some wood ash or lime to lower that. Then, in the fall, aerate the lawn to relieve the soil compaction and lay down premium topsoil or compost on those bare spots, and then lay down seed. Then, by the springtime, he’ll have a nice stand of grass. And as long as you leave the clippings behind every time you mow the lawn, in a damp climate like Michigan’s, that lawn will probably never need to be fed. “It should be self-sustaining if you leave the clippings where they lie, because they’re 10% nitrogen. You’ll be feeding the lawn every time you cut it.”

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