The lawn and short of it

My lawn is OK but not great. What can I do now to ensure a nicer lawn this summer?

Until the lawn is no longer wet and spongy, the best thing you can do is stay off it. Foot and vehicle traffic compacts spring soils, encouraging weeds to thrive and grass to struggle.

Ask a master gardener

Crow Wing County Master Gardeners are trained and certified volunteers for the University of Minnesota Extension Service. All information given in this column is based on research and information provided by the university. To ask a question, call the Master Gardener Help Line at 824-1000, extension 4040, and leave a message. A master gardener will return your call.

When conditions are right, remove winter debris such as twigs and pine cones. Rake up or mulch-mow excessive leaf cover. If you have dead spots from salt damage or pet urine, flush them with a hose to dilute their concentration. Then, when the soil is no longer wet, scruff up those spots with a garden rake and shake grass seed evenly and generously over them, Tamp gently and keep moist through the first couple of mowings. Overseeding an entire lawn can be beneficial also. Be sure to read grass seed labels. In our area, Kentucky blue grass is best for sunny lawns and fescues for shade. A mixture of both, along with perennial and annual ryegrass, is often the best choice for many lawns.

I heard that the emerald ash borer has reached Minnesota. Is there anything I can do to protect my ash trees?

The emerald ash borer is of great concern to Minnesotans as we have the second largest population of ash trees in the U.S. This pest has already killed tens of millions of ash trees in the U.S. and Canada. Last spring, the emerald ash borer was discovered in St. Paul and in February the Minnesota Department of Agriculture confirmed an infestation of the EAB in four trees in Minneapolis.

Ash trees cannot defend themselves against the emerald ash borer; if an ash is attacked it will die. According to the Minnesota Department of Agriculture, do not apply insecticides to ash trees out of the likely range of EAB. Currently, Houston, Ramsey and Hennepin counties are under quarantine, so ash trees more than 15 miles beyond this range are out of the likely range of EAB. The Minnesota Department of Agriculture also reminds homeowners that it is not necessary to remove healthy ash trees.

It is important not to transport firewood, even within Minnesota. A major reason for the spread of EAB has been due to transporting firewood or landscape trees that have larvae burrowed under the bark.

Last spring I planted two shrub roses and wonder when and if I should prune them. What do you think?

Spring is the best time to prune roses. Your goal will be to remove dead, diseased and damaged canes, to increase air circulation and to improve and enhance the plant's shape.

There is often some winter kill, even on shrub roses. Some may die back to the ground but will send out new growth as the weather warms. Always prune back to good, green wood with a diagonal 45-degree cut a quarter inch above an outward facing bud, which means that the new growth at that point will be away from the center of the plant.

When possible you will want to open the plant center to good air circulation. As a general rule of thumb, woody plants can have up to a third of their canes removed before damage occurs.

I have a hibiscus that I received last year for Mother's Day and have as a house plant, but I have heard that there is a hibiscus that grows in Minnesota. Can my hibiscus be planted outside?

The plant you have in your home is most likely the tropical hibiscus, Hibiscus rosa sinensis. You may put your plant outside during the summer in a sunny location, but because it is a tropical plant, you will have to bring it back in before it gets too cold in the fall if you want to keep it.

There is a cold-hardy hibiscus, also known as "rose mallow" that you may find in garden centers. These beautiful perennials are hardy to Zone 4 (we are Zone 3 in the Brainerd Lakes area) and need to be mulched for winter protection. Gardeners up here have been successful growing some Zone 4 perennials due to micro-climates within their yards or heavy mulching in the fall for winter protection.

Unlike the tropical hibiscus, the hardy hibiscus does not bloom continuously all summer. It does have a long blooming season, which goes from mid-summer until frost. There are some spectacular cultivars with show-stopping, huge flowers in shades of pink, red, white and lavender.

The cultivar "Kopper King" has six-inch pale pink blooms with bronze foliage. Like its tropical cousin, the flower on the hardy hibiscus only lasts one day but new buds keep opening. These perennials perform best in full sun and prefer a slightly acidic soil with plenty organic material.

Tropical hibiscuses growing in pots need regular fertilizing every two to three weeks during the growing season, but like other perennials, hardy hibiscuses should be fertilized once in the spring. The hardy hibiscus does well in moist or dry conditions. In fact, they are a good choice for rain gardens, due to their tolerance of wet soils. The beautiful hardy hibiscus is relatively pest-free and disease-resistant so it may be a perennial worth trying in your garden if you are willing to give it some winter protection in the fall.

Should my apple trees be pruned in the spring?

Apple and crabapple trees, mountain ash, hawthorns, and shrub cotoneaster should be pruned in late winter (February to early April). Spring or summer pruning increases the chance of infection and the spread of fireblight, a bacterial disease.

Ideally, pruning should be done when the tree is young. The dormant season following planting is a good time to shape trees. Don't cut back the leader. Remove crossing branches, branches that grow back towards the center of the tree, dead or dying branches.