Ask the Master Gardener: Alder trees are functional and beautiful
Because they have aggressive growth potential and improve soils, alders are useful for land reclamation after disturbances.
Dear Master Gardener: My wife and I were shopping for cabinetry and doors for our remodeling project and noticed that knotty alder is a very attractive and popular wood right now for cabinets and doors. Do alder trees grow in Minnesota?
Answer: Alder trees are in the birch family (Betulaceae) and the genus Alnus. Alders tend to grow in wet, slightly acidic soils especially along the edges of wetlands. The speckled alder grows in Minnesota and has gray bark that is interrupted with pale warty lenticels. Alders form a symbiotic relationship with a nitrogen fixing fungus in their roots and convert nitrogen from the air to a usable form in the soils. This not only allows the tree to grow well in very poor soils, but also makes nitrogen available to other plants growing nearby. Just like adding legumes can improve the life of our gardens, alders perform the same function in the forest, often benefiting the trees, shrubs and understory plants around them. Because they have aggressive growth potential and improve soils, they are useful for land reclamation after disturbances. The alder can actually be beautiful and functional and can be trained to a tree-like form by removing lower branches.
The alder that is most commonly used in woodworking is the red alder, which is a North American hardwood typically found in the Pacific Northwest. It can range from rustic with heartwood, streaks, pin holes and open knots to clear and unmarked. It is a softer wood than maple or cherry, has consistent color, stability, and accepts stains and finishes very well, so it is an excellent species for furniture and cabinetry.
March Gardening Tips
- Heavy spring snowfall often weighs down evergreen boughs. It’s probably best to just let the snow melt off on its own. If you want to remove it from your evergreens, scoop it off gently rather than hitting the branches, which are still brittle this time of year and prone to breaking.
- Sharpen pruning tools with a sharpening stone or have them professionally sharpened because there are lots of pruning opportunities this month.
- Now is the time to prune apple, crabapple, oak, maple, birch, honey locust, mountain ash, hawthorn, butternut, walnut, ironwood, and beech trees. Pruning wounds need no paint!
- Check for black knot, a fungal disease, on chokecherries and other members of the cherry family. Look for hard swollen black galls (tumor-like growths) that form on branches and sometimes on trunks. Make the pruning cut at least 4 inches below the black knot gall. It is best to prune when temperatures are below freezing to prevent black knot spores from infecting the pruning wound. If possible, dip your pruners into a bleach solution between cuts.
- Red twig dogwood stems have provided color all winter, but old stems lose their color over the years. Now is a good time to prune out older, duller, thicker stems.
- Prune hydrangeas (that bloom on new wood) to the first pair of buds above ground or 3 feet up if you want stronger, less floppy stems — as soon as you can find them underneath all the snow!
- Prune grapes before new growth emerges. They will overproduce and have small fruit unless the vines are pruned every year.
- Cut back yellow and red raspberry canes to 4 to 5 feet tall before new growth begins.
- Now is a good time to repot overgrown houseplants. Use a fresh pot one size larger than the overgrown one with drainage holes in the bottom. A coffee filter can be placed on the bottom to keep soil from going through the drainage holes. Add new potting soil and water well. Fertilize all interior plants with a liquid fertilizer mixed at one-half strength when you see new growth forming.
- Florists and nurseries will be offering “shamrock plants” this month to celebrate St. Patrick’s Day. Even though the green or burgundy leaves are shamrock-shaped, these houseplants are not shamrocks, but members of the genus Oxalis. Choose Oxalis plants with lush, healthy foliage and lots of new flower buds. To thrive indoors, these plants prefer cool conditions and bright light, especially when in bloom. Oxalis leaves open in bright light and close at night.
- By the middle of the month start seeds for annuals such as ageratum, coleus, dusty miller, nicotiana, dianthus (pinks), snapdragons, and verbena. Seeds for alyssum, cleome, moss rose, and salvia should be started at the end of the month. Check seed packets for seed starting information as species and cultivars will vary.
- At the end of the month, start seeds for warm-season crops such as tomatoes, peppers, and herbs. Use sterile seed-starting mix and clean containers with good drainage. Keep soil warm and moist. Place seedlings in a bright window or under artificial lights.
- If you have old seeds you can check for viability by laying the seeds on a damp paper towel, folding the towel over the seeds, and placing them in a resealable plastic bag. Place in a warm location and check for germination over the next week. Carefully remove the germinated seeds from the towel and plant them in pots.
- Move plants you have been overwintering into a sunny window. Cut off dead leaves and stems and start watering. Fertilize when you see new growth.
- Pot up stored geranium and tuberous begonias. Place them under lights or in a sunny window. They should be ready to bloom by Memorial Day.
- Toward the end of the month, cut some branches of pussy willow, forsythia, flowering plums or other spring blooming plants to force them to bloom indoors. Recut the stems and place in containers of warm water in indirect light. Move them to brighter light as the flower buds open and enjoy an early touch of spring!
- When the snow melts you may see vole damage in your lawn. If so, rake up any dead grass and reseed the area when the soil warms up.
- Choose a nice day and, if it’s not frozen solid, turn your compost pile to get it heating up again.
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 firstname.lastname@example.org 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.