Q.: I have some green foundation shrubs that I think are called yews. Every spring, they send out a cloud of yellow dust. Is this caused by a fungus? I have children and am worried theyíll be hurt by the fungus. What should I do?
A.: Spring will soon be in the air! The yellow powder you observe each spring is pollen, produced in tiny male cones on the taxus (or yew) plant. This pollen is not toxic, and shouldnít cause a problem for the children unless they are prone to seasonal allergies.
Keep in mind, however, that virtually all parts of the taxus plant are toxic, especially the seeds. The seeds are surrounded by a red fleshy fruit-like structure called an aril. Many forms of wildlife are able to eat these arils without any toxic effects, either by breaking down the seedís toxin or expelling the undigested seeds.
A fellow horticulturist shares a story about being contacted by the county coroner, who was investigating a death following the consumption of taxus tea. Teach your children to enjoy looking at the plants, but never eat anything in the garden.
Q.: I love having fresh flowers indoors. How do I know what stems I can cut to force indoors? Can I cut bulb flowers, and will it affect the bulbsí return next year?
A.: Nothing brightens up the indoors like a the color and fragrance of flowers. Right now in my kitchen, I have cornelian cherry dogwood, star magnolia, forsythia, weeping cherry and crab apple twigs in bloom.
As a general rule, twigs from most any spring-blooming shrub can be cut and brought indoors as early as January, and up until the time they would normally bloom outdoors. This can make winter pruning especially rewarding, knowing that branches can be cut and enjoyed for weeks indoors. The one shrub Iíve never had much luck with is lilac; Iíve tried to force them, but the flower cluster ends up wilting on the branch.
As for the bulbs, cut and enjoy bulb flowers to your heartís content. Daffodils, tulips, hyacinths and other spring bulbs are not affected by having flowers cut. What can damage the bulb is early removal of leaves before they have naturally yellowed. The leaves are making food to ensure the return of the bulb next year, so leave them alone until they begin to yellow on their own.
Q.: I want to put down a pre-emergent herbicide for crabgrass, but I also need to overseed my lawn. Most of my weed problems are from that little plant with a white flower; it sends up a stalk of flowers, and has feathery leaves. Itís spreading through the lawn.
A.: The weed you describe sounds like bittercress, a member of the mustard family that fares well in cool temperatures. Applying a pre-emergent herbicide now will have no effect on bittercress, since these plants are already up and growing. Bittercress seeds germinated in fall and through the winter. Pre-emergent herbicides will break down over time, so the spring application will break down before bittercress seeds germinate in fall.
If your lawn isnít dense, I would recommend trying to develop a thicker turf instead of applying a pre-emergent product. While this herbicide will prevent weed seeds (like crabgrass and chick weed) from germinating, it will also prevent grass seed from growing.
A lush, dense turf is naturally able to shade and crowd out weed seeds, so time spent developing a thick, healthy lawn will help to avoid weed problems in the future. Gardeners using a pre-emergent herbicide this spring will be able to put down seed this fall. Wait to apply crabgrass (pre-emergent) herbicides until flowering pears are in bloom, hopefully in a few short weeks.
Q.: Every year, I plant containers on my patio. I have been using a high-quality potting mix and I wonder when I should replace the soil. What can I add to revive the container mix? Itís expensive to replace the soil every year.
A.: Good for you for using a high-quality potting mix. While these mixes are more costly at the outset, they provide the right conditions for healthy plant growth, including good air spaces and the ability to hold available water.
Most good mixes are composed of peat moss, vermiculite and perlite; some have wetting agents or fertilizers as well. Plain old potting soil or top soil is a heavy mineral soil that compacts quickly, can hold too much water, and will deprive plants of oxygen and available water.
To refresh potting soil in containers, add about a third (by volume) new potting mix and combine thoroughly. Take out any hard root clumps from last yearís plants. Alternatively, some gardeners completely replace the soil every three years.
Q.: My neighbor had a few oak branches extending out over the street, so they cut the branches off where they overhung, about six feet from the trunk. Is it better to do this, or to cut the branch all the way back at the trunk?
A.: Many difficult pruning decisions can be avoided by planning ahead and pruning early in a treeís life.
Trees donít heal from cuts, but they do produce callus tissue to seal off wounds. Small pruning cuts on young branches are more readily callused over than large cuts. Pruning branches off of young trees up to about 6 feet (so they can be walked or mowed under) at an early age avoids having to take out large branches later in life.
At any stage, itís much better to remove a branch at the branch collar, where the branch meets the trunk, than to leave a cut-off stub six feet from the trunk. This stub can provide easy entry for insects or disease organisms to enter the tree.
Denise Ellsworth directs the honeybee and native pollinator education program for the Ohio State University. If you have questions about caring for your garden, contact her at 330-263-3700 or click on the Ask Denise link on her blog at www.osugarden.com.