Magnolias for Minnesota
Wonderful blossoms, hardy trees, great leaves – Magnolias are a joy in the Spring. While we can’t grow the big southern varieties, there are several lovely Magnolias for Minnesota. All magnolias prefer similar situations: loose soil with lots of organic material, like the forest edges where they developed; ample moisture that drains readily and doesn’t puddle, lots of sun except in the hot late afternoon, and protection from cold and drying winter winds. The best location, then, would be on the east side of a building or tree belt in soil that is slightly acidic and neither all sand nor clay. Like Azaleas and Rhododendrons, Magnolias have fairly shallow root systems. Plant with the root flare visible, and tease the roots out gently. Planting in a cylindrical hole is the worst possible treatment: the shallower and wider the better. The natural site for magnolias is on the edge of forest clearings, quite often just above a small pool. That is, protective woods on three sides, dappled sun, porous soil and ample moisture, with a pH of 6.5. Many sites in the Twin Cities can match this, especially in the north east and western suburbs, along the Mississippi, parts of the Lakeville-Apple Valley corridor, and some of the Anoka Sand Plain.
Care of Magnolias
• Once properly planted, the aim with Magnolias is to ensure that the soil is slightly acid. Remember that city water is very alkaline, so use acid mulch, such as cottonseed meal, or apply elemental sulfur each spring. An acid water-soluble fertilizer is not much use with these woody plants, but the pellets or spikes for evergreens will give a nice slow-release acid fertilizing right after the bloom fades. Mulch with compost – your own if possible
• Pruning is not a big concern. Most of these plants will do just fine without it, and they tend to be shrubby. If you wish to have a “tree form” plant, prune out any sprouts from the roots, and cut off side branches up as high as you wish. If you must prune, do it just after the flowers fade, and cut as little as possible to get your desired shape. Pinching out 1/3 of each new growth shoot right after flowering will result in a denser plant with more blooms.
• Magnolias are extraordinary healthy and free of insect problems when grown in the proper site. Very occasionally they get scale, which can be eliminated with horticultural oil treatment.
• Magnolias are great underplanted with Scilla siberica or Grape Hyacinths, followed by Ajuga or Lamium. The shallow-rooted ground covers aren’t too much competition. Integrating Magnolias into borders of shrubs and perennials is not difficult, but keep in mind their shallow, fibrous root system, and keep competition to a minimum. Clethra, Boxwood, Ilex glabra, Rhododendrons and Azaleas, Winterberry and some of the Viburnums would be good companions in a shrub border. Anemone, Bergenia, Brunnera, Columbine, Ferns, Geraniums, Polemonium, Pulmonaria, Tiarella, Chelone and native woodland plants are great perennial companions in the perennial border.
While we all know the big southern magnolia, there is in fact a magnolia native to Minnesota. The Cucumber Tree, Magnolia acuminata, gets really big – 80 feet tall and 60 feet wide. It is the parent of several hardy hybrids, and the source of all the hardy Magnolias with yellow flowers. Bachman’s carries these magnolias:
• ‘Butterflies’ is a selection of M. acuminata growing to 20’ tall and wide. ‘Elizabeth’ is its cousin at 30’ tall and wide. Both have yellow blooms from April to May.
• ‘Jane’ is a hybrid with flowers that are purple on the outside and white inside. Blooming in early May, ‘Jane’ gets 8’-12’ tall and wide. It often flowers again in late summer.
• The loebneri hybrids include ‘Leonard Messel’ with rosy purple buds opening to soft pink, and ‘Merrill’ with fragrant white blooms. ‘Leonard Messel’ can reach 20’x25’, and ‘Merrill’ 30’x30’.
• ‘Stellata’ varieties (‘Royal Star’) have double white blooms. A bit smaller, this variety grows to 10’x10’. Probably the hardiest of the lot.
• ‘Susan’ is a lilifolia variety with a smaller, compact shape. The red-purple buds open into slightly twisted, wavy petals. ‘Ricki’ is similar, but with a narrower profile. It is great for a courtyard or other protected spot.
• [A dream garden: Magnolia ‘Jane’, single pink Tree Peonies with a pale yellow center, Clethra ‘Ruby Spice’, Clematis ‘Hagley Hybrid’, lots of Anemone huphensis, Lamium ‘Pink Pewter’, Geranium ‘Claridge Druce’ (or maybe Biokovo or Bevan), and perhaps Siberian Iris ‘Butter & Sugar’). Maidenhair ferns in the back, and behind that Jack in the Pulpit, Solomon’s Seal and other woodland natives.]
Related Bachman’s Products
• Azaleas, Rhododendrons
• Bulbs, Perennials & Shrubs
• Bonie ‘Plant Starter’
• Cottonseed Meal
• Soil Sulfur
• Jobe’s Fertilizer Spikes for Evergreens
© Bachman's 2003
Jackie Alfonso, Horticulturist