Q. I would like to create a circular flower garden in my backyard, and really like the look of the retaining wall stones that have become so popular. I need to know a simple calculation or some websites that will help me calculate the needed materials. I also need help in the keeping the spacing exact enough to make both levels come out to an exact block count. This is to prevent having to cut the blocks. The retaining wall blocks have a lip on the back and bottom of the block and will cause the circle to get smaller as each layer goes on. Should I just chisel off the lip, since the blocks really will not be supporting much weight?
A. It will not be exact, but measure the length of the block and divide it into the perimeter of the bed. Many of the blocks are longer along the midline of the length for flexibility. Adjust the perimeter to come up with whole blocks. A bed sixteen feet in diameter would have a perimeter of 50 feet, divided by the 16-inch length of a block would require approximately 37 blocks to lay the perimeter. Each course of blocks would take the same number. You calculate the perimeter by multiplying the diameter by pi. Leave the lip in place because it seems that even a 3-course wall looks nicer with the setback. Of course, it is up to you.
Q. I have a nice stand of Bermuda grass in my small front yard, but the soil is uneven so it cuts unevenly. I need to level the soil. Any suggestions for smoothing out the dips?
A. Mixes of sand and some potting soil or just sand by itself can be added to the dips. The grass should readily grow into the space. If you do not fill too much at a time, the grass will adapt the deeper soil and "move up" to grow in the deeper soil.
Q. How do I remove the dirt that's left behind from the holes being dug for fence posts? I don't want to kill the grass.
A. You could spread it out around the yard lightly, or use it to level any low areas in the lawn. If you have warm season turf, it will grow through without a problem. If you have cool season turf, you can reseed it now. If you spread it out lightly, you will not need to reseed. Only if you bury the turf will seeding be necessary.
TIP: Our expert gardening advisor, Susan Patterson adds, "When digging holes for fence posts always put the dirt in a wheelbarrow or on a tarp so that it does not damage sod."
Q. In the spring, I plan on redoing my backyard and need some tips. The previous owner had built the driveway so that it was a few feet above the backyard, leaving a drop with a couple of steps from the drive to the yard. What we want to do is to bring in some dirt and slope the yard up to the driveway and then replant the entire yard. Now for my question: What is the best way to kill off the grass that is currently in the yard so that we can successfully replant next spring?
A. If you are going to fill that much, the soil that you are importing will kill off the turf under it anywhere that the depth is more than an inch or so, the exception being if you have quack grass or something similar. Roundup is a non-selective herbicide that will have effect on most (not all - see product label to find out what it is registered to control) weeds and grass types. You could do a blanket application to kill everything off and then, after seven to ten days, re-seed or sod.
TIP: Susan suggests, "If you are looking to kill and area of sod without using a chemical you can cover the area with black plastic and smother the grass."
Most turf grasses need ground temperaturess of at least 60 degrees F to germinate, and depending on variety or type you pick, may germinate in as little as five days to a month or more. Once again, depending on the variety you select, it will require from a month to most of the season to fill in and be usable. Your County Agent or local Co-operative Extension should be able to help you make a selection of grass type if you tell them your expectations and uses of the areas.
I am not sure what the slope of the area is, but you might want to consider holding off on bringing in the fill until you are ready to seed/sod so that heavy rains won't wash away your efforts. Also, sodding may be preferable to seeding for the same reason at least on the sloped areas.
Q. I have some bare spots in my yard that are covered with creeping juniper. Do you have any suggestions on when is the best time to replant and how should I prepare?
A. Creeping juniper is easy to grow, drought tolerant and low maintenance landscaping. You should be able to find it in local garden centers in the spring. Dig a bowl-shaped hole twice as wide as deep. Don't dig a hole too deep as plants may settle too deep. As you dig, mix in a 2-inch deep layer of planting mix, compost, or other type of organic matter. Don't plant too deeply. Make sure that the topmost roots are covered with about 1/2 inch of soil, but avoid piling soil or mulch up around the main stem. Always water plants the day before planting and water the ground after you are finished setting out a new shrub. When the dampened soil settles, spread a 2- to 3-inch deep blanket of mulch to control weeds and keep the soil moist.
Q. I have holes in the sod. Either the rain has settled the dirt or I did not roll or compact the ground enough. Some holes are small like a footprint and some larger.
A. If soil was raked smooth, flat, and properly watered and sod rolled, the sod should have knitted to soil within two weeks. Holes can be plugged with sod in late spring just before the prime growing time of grass. You can purchase plugs or cut your own out of sod. Re-rolling the lawn may help.
Q. In so many landscaped places, I see that the area immediately around trees is in a perfect circle (or close to it). I have tried to use an edger (mine does not allow any adjustments), and a shovel to dig it out. Unfortunately, I can never make the circles look that good. How can I do this?
A. You can take a tape measure and measure out from the tree trunk in several places to make sure the depth of the bed will be the same all the way around the tree. You can mark the locations with stakes or flour or lime and then connect the 'dots' by sprinkling flour or lime to outline where you want to dig. Press a shovel into the soil along this line. Or, you can simply stretch a water hose around the tree and use it to guide you. You will want the edge along the perimeter to be a little deeper to act as a lip to keep mulch in the bed and looking tidy. When mowing, turn the mower so grass clippings do not go into the bed if you're not using a grass catcher.
Maintain the boundary between the lawn and flowerbed by edging with a flat spade, half-moon edger, or weed-trimmer. You can also work a variety of edging materials into your plan, including products made from metal or plastic, bricks, fieldstones, or pavers. Remember anything planted in a bed beneath a tree must compete for moisture with the tree. Make plant selections that can thrive in the growing conditions beneath the tree.
Q. There are some relatively rocky sections of my property that get sun, but are mostly dirt and weeds right now. I guess I could rent a rotor tiller to get the ground soft to plant grass seed, but how do I get rid of all these tall weed plants?
A. Loosening the soil and removing rocks will get you a good start. The weeds can be pulled or cut back and sprayed with a general herbicide such as Roundup. Roundup is taken best in new growth when temperatures are above 70 degrees F. Cutting the weeds back will force new growth in a couple of days. Spraying the new growth will be the best way to apply the herbicide.
Q. I have a wooded area at the back of my property. I have thinned out the trees and will be removing the stumps in the next week. I used two Roundup applications and it's almost entirely clear of weeds. Any remaining weeds are small new weeds or just tufts of grasses. I'm thinking of just tilling the remaining weeds into the soil and covering with about 2-4 inches of new topsoil and reseeding with grass. Will the grass seed choke out any new weeds that might try to grow when I water the germinating grass, or will I need to make sure that all of the weeds are 100% dead before I cover with new soil and reseed?
A. I would spray one more time, then till the next day and apply the topsoil. You will have to deal with the weeds that sprout from turning the soil and repositioning the seeds in the soil. As the grass comes in, you will have to deal with some weeds, too. The grass will choke out weeds once it becomes thick.
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