Ask a master gardener

Dear master gardener: I would like to put in an herb garden this year. How do I get started?

June garden tips

Resist the temptation to cut or pull off or tie together the unattractive leaves of daffodils, tulips and other spring-flowering bulbs. Leave them until they are no longer green. Keep fertilizing until they are brown and withered because the foliage continues to gather energy to nourish the bulb for next year.

Water lawns and gardens early in the day. Night watering encourages a number of plant diseases. Conserve water by watering plants close to their bases. Use soaker hoses when possible and avoid sprinklers that shoot water high into the air where much of it evaporates.

Container plants dry out quickly. Check them daily because daily watering will usually be necessary. Since frequent watering leaches fertilizer and nutrients through the soil, use water soluble fertilizers weekly.

Emerald ash borers are not a problem in our area yet, but read up on them and be on the lookout for them because they may reach us in the near future.

Anthracnose is a fungal disease that shows up almost every year on ash, maple and sometimes oak trees. It causes large dark blotches on leaves, many of which drop. Only rarely is it severe enough to damage trees. Rake up and dispose of fallen leaves. Fungicide is not necessary.

Many houseplants benefit from a summer spent outdoors. Keep them in relatively shady spots and water frequently.

New trees and shrubs need frequent water. Place about three inches of mulch around them, leaving about an inch of air space around the stems or trunks. Annuals and most vegetables, on the other hand, need warm soils, so put off mulching them until late June.

Leave lawn clippings on the lawn. They fertilize the grass. If your mower is leaving unsightly rows and clumps, you are waiting too long between mowings. Remove only about an inch of grass at a time. Raise the height of the mower blade as we enter hotter, drier weather.

Check evergreens for sawflies, yellow-green caterpillar-like larvae with voracious appetites. They seldom kill a tree but can impair health and vigor. For good control they must be treated when about 1/3 inch long.

Now is the best time to prune lilacs. They will soon set the buds for next year's flowers.

You may want to start out by getting your soil tested through the University of Minnesota extension office. Most herbs prefer well-drained soil with a pH of 6.0-7.5. Do not plant your herbs in soils with a high nutrient content because rich soil may harm the herb's quality. In addition, most herbs need a minimum of six hours of sunlight and all-day sun is better, so place your herb garden where it gets enough sun exposure. More intense light will develop more oils within the foliage, which will in turn develop stronger fragrances and seasonings.

There are two plant families in which many of the common herbs grown in Minnesota fall into. Basil, oregano, marjoram, rosemary, thyme, sage, summer savory and the various mints are in the mint family. These herbs are all grown for their aromatic leaves. Dill, parsley, cilantro, fennel, and chervil are in the carrot family and are grown for foliage and some for seeds. Some other popular culinary herbs that come from different plant families are chives and tarragon.

After your herbs are planted, water your herb garden thoroughly and deeply once a week. If you are growing herbs in containers you will need to water them more frequently. Use fertilizer sparingly. Apply a 5-10-5 fertilizer at the rate of three ounces every 10 feet of row once during the growing season. For herbs in containers use a liquid fertilizer at half-strength once every three to four weeks.

You may harvest your culinary herbs throughout the growing season by snipping leaves and sprigs as needed. Mid-morning hours are the best time to pick herbs because the oil content is highest. Many herbs will have the best flavor if you harvest them just before they flower. If you let annual herbs flower, the flavor of the herb will decline and it will be the plant's demise.

Dear master gardener: Why do my hostas get holes in them?

It sounds like slugs are damaging your hostas. They not only cause a lot of damage to hostas, but other plants as well, especially seedlings. They thrive in rainy weather, well-watered and well-mulched gardens. If you have mulch in your garden, try to keep it less than three inches thick and avoid large wood chips. Water your garden in the morning and only when it is necessary.

If you would like to trap slugs, sink shallow containers of beer in the ground with the rim even to the ground. The slugs are attracted to the beer, fall in, and drown. If your garden is small you could use copper strips or tape as a barrier. There are commercial products such as Sluggo and Escar-Go, which are iron phosphate bait granules that you add to the soil, or Deadline or Defender, which are metaldehyde baits. All these products, with the exception of beer, may be found at local garden supply stores.

Dear master gardener: We have a lake cabin in Crow Wing County and come up here every weekend from Memorial Day through Labor Day. I'd like to grow some flowers and vegetables in pots but won't be here Monday through Friday to water them. Can you suggest plants that might survive under those conditions?

You pose a tough problem. Most flowers will not survive, let alone thrive, under such conditions. If they are in hanging containers, their survival is even less likely because such containers dry out with great speed, needing water more than once a day when it's hot and/or windy.

Some cacti and sedums might grow for you. Flowering requires more moisture than foliage does so plants with interesting foliage might stand a greater chance of surviving. Dry soil foliage plants that you might try include love-lies-bleeding (Amaranthus caudatus), variegated pigeonberry (Dichondra argentea), variegated snow in summer, (Euphorbia marginata), variegated or blue Marguerite (Felicia amelloides), variegated lantana (Lantana camara), purple fountaingrass (Pennisetum setaceum), dusty miller (Senecio) and variegated nasturtium (Tropaeolum major variegata).

If you place planted containers in a sheltered spot on the ground while you are not present, they might do reasonably well. Other suggestions would be to plant both flowers and vegetable in the ground and water them with a hose set on a timer or call upon a friendly neighbor who would water once or twice during the week while you are gone.

Dear master gardener: I would like to grow more native plants but don't know what to grow or where to get them. Do you have any suggestions?

The good news is that more and more people are becoming interested in growing native plants so that many local garden centers now carry them. The temporary and big-box stores are less likely to do so.

Let's begin with a definition of a "native plant." It is a plant that grew naturally in a specific area before the European settlement of America and thrives best in that soil and climate. Some natives, such as purple coneflowers, grow easily and abundantly under many and varied conditions. Others, such as native orchids, have very specific and uncommon needs. Natives tend to be more disease and insect-free than non-natives but they also tend to be less colorful and have shorter bloom time.

Because there are hundreds of native plants and shrubs and because they vary greatly in their soil, light and water needs, a list of them here that would fit your specific site and needs would be impractical. For an example, let's assume that you are looking for spring-blooming plants for a shady area in your yard. You might consider columbine, jack-inthe-pulpit, wild geranium, merrybells, culver's root, anemone and bloodroot, among others. Books on native Minnesota plants and googling "native Minnesota plants" will give you much more information.

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 (218) 824-1000, extension 4040, and leave a message. A Master Gardener will return your call.