Dear Master Gardener: I bought hyacinth bulbs this week only to find out they are not hardy here. Can I force them to bloom this winter in my house?

Answer: Unfortunately, hyacinths are not hardy in zone 3, but the good news is you can force them to bloom indoors and fill your home with fragrance. Forcing is a technique that lets you bring plants into bloom before they would normally flower in your garden. Like most other spring-blooming bulbs, hyacinths need to go through a chilling period in order to bloom properly. Plant your hyacinth bulbs in a container with a drainage hole on the bottom and use a high-quality, sterile potting mix. Fill each container half-way with potting soil and nestle the bulbs pointy side up about an inch apart. When the bulbs are in position, place more potting soil around the bulbs, but don’t completely cover them. Allow the tips to stick above the soil. Chill your bulbs in a refrigerator or in a dark area with consistent temperatures of 35-48 degrees for about 13 weeks. If you store them in a refrigerator, make sure not to store any fruit in there at the same time because the ethylene gas given off by ripening fruit will damage the embryonic flowers inside the bulbs. Keep the soil lightly moist.

Hyacinths can also be grown without any soil. There is a specific forcing vase designed for this purpose. It has a wide base to contain the water and roots and a narrow neck to hold the bulb so it doesn’t quite touch the water. The bulbs still need to be pre-chilled, which you can do before putting them in the vase or put them in the vase and then chill them. When the plants have grown to two inches, move the pots or forcing vases to a window with indirect light. When the buds begin to show color, move the plants to a sunny window. When the flowers open keep them in a cool location out of direct sunlight so they bloom longer.

Related: Ask the Master Gardener: Don’t take down those hummingbird feeders just yet

Dear Master Gardener: I would like a beautiful accent shrub. Are there any flowering shrubs that can be grown as a standard?

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Answer: An accent plant draws your attention to it acting a lot like an exclamation point in the landscape. Accent plants can be mixed into perennial borders or beds with stunning results. A flowering standard shrub adds a lot of visual interest and can be a real showstopper. A standard is a shrub that has been grafted onto the trunk of a tree to add height and dimension. Lilacs and hydrangeas make nice standards. Ninebarks can be grafted into a tree form also, but the blooms aren’t as showy as lilacs and hydrangeas. Dwarf Korean lilac (which originates from China not Korea as the name suggests) is also known as Meyer lilac. It is sometimes grafted on a separate rootstock to produce a small, globe-headed tree. It is hardy to 35 below zero and has moderate fragrance. Many Hydrangea paniculata (panicle hydrangea) can be pruned into a tree form, but typically the taller varieties are used. It takes a nursery grower more than five years to bring a panicle hydrangea tree form to market, so they can be somewhat expensive. Limelight, Vanilla Strawberry, and Quick Fire are the varieties found most often as a tree form. They all mature to about 6 to 8 feet tall and bloom in August and into September.

Related: Ask the Master Gardener: Add water when clematis plants are browning from the bottom up

Dear Master Gardener: I would like to plant some maple trees to get my own maple syrup. Which ones should I plant and how big do they get?

Answer: Now is a good time to plant trees. There are four species used for producing maple syrup: Acer saccharum (sugar maple, hard maple); Acer rubrum (red maple); Acer saccharinum (silver maple); Acer negundo (boxelder, Manitoba maple). All four are native to Minnesota. Plant them in full to part sun.

Most maple syrup is made from sugar maple sap. Sugar maple sap is preferred because it has an average sugar content of 2%. Because sap from other maple species is usually lower in sugar content, approximately twice as much is needed to yield the same amount of finished syrup. If processed carefully, syrup from any of the maples named above will have good flavor. Ornamental maples, such as the Norway maple, have a milky sap and cannot be used for syrup production.

Related: Ask the Master Gardener: Oleanders can be houseplants, but be wary of their toxicity

The sugar maple is a beautiful, majestic tree that reaches a mature height of 75-100 feet and spread of 50-75 feet. Red maples reach a mature height of 40-100 feet and spread of 15-75 feet depending on the cultivar. The following red maple cultivars are hardy to zone 3: Autumn Spire, Northfire, Northwood, and Scarlet Jewell. A silver maple is a fast-growing tree reaching a mature height and width of 75-100 feet. Plant them away from structures because the root systems of silver maples grow vigorously and superficially and can penetrate drain tile and sewer lines, raise or buckle sidewalks, and make mowing difficult. Boxelder reaches a mature height and width of 35-60 feet.

Dear Master Gardener: The thistles in my yard are getting out of control. How can I effectively eliminate them?

Answer: Thistles can be troublesome weeds in Minnesota yards. First, you need to identify what type of thistle you have for proper thistle control. Biennial thistles form a low growing rosette of leaves the first year and a taller flower and seed-bearing stem the next year. It is best to eliminate them the first year, so they don’t have a chance to bloom and produce seeds. Biennial thistles can be controlled by digging and cultivation. Perennial thistles come back each year from roots that survive the winter. They bloom and set seed yearly and spread by creeping underground stems (rhizomes). The most effective way to remove perennial thistles is through the use of herbicides. Broadleaf herbicides containing 2,4-D and MCPP can control thistles in lawns. In gardens, it may be best to spot treat thistles with a non-selective herbicide containing glyphosate, such as Round-up. Herbicides must be applied when weeds are actively growing and air temperatures are about 60-85 degrees. The best times to control weeds are in the fall (September through mid-October) or spring (late April through mid-June). Always read and follow all pesticide label directions carefully.

Related: Ask the Master Gardener: Gardeners experiencing common tomato disorders

You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A master gardener will return your call. Or, emailing me at and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.