When is the best time to plant in Minnesota? The answer depends largely on what type of plants you're putting into the ground. For many, early autumn is often as good a time as spring -- and in some instances, better.
Spring-flowering bulbs, for example, should be planted in fall, though early enough to receive adequate moisture to develop plenty of roots before the soil freezes.
Timing is the key to successful fall planting. In general, the longer you wait, the more risk factors come into play.
Sod that's laid in early autumn will "knit down," or root well into the soil, and emerge from winter in good condition. However, if you wait until late November when the soil has already frozen, the sod won't knit down, leaving it more vulnerable to damage if snow cover is poor or absent.
Other plants you can add to the landscape now:
Most flowering perennials do well planted this time of year. The rule of thumb has always been to plant late-flowering perennials in spring and early-flowering perennials in fall. But you should be able to plant most container-grown perennials from a nursery or garden center in early autumn. Just make sure there's still at least three or four weeks of decent growing conditions left when you put them in the ground. That should give the plants enough time for their roots to resume growth once they're in the ground.
You can also divide perennials -- irises, daylilies, peonies, hostas and others -- and replant them right away.
Mulch around planted or replanted perennials and water them regularly if rainfall is sparse. Fall-planted perennials also need added winter protection the first year. Once the soil freezes (usually in November in the Twin Cities), cover them with a thick layer of mulch -- 4 to 6 inches of straw or marsh hay or 10 to 12 inches of fallen leaves.
Pansies should be available at garden centers any day. These plants, which can withstand light frosts, will thrive as nights grow longer and cooler. With luck, you'll get a couple of months' worth of blooms before a hard frost knocks them back to the ground. Sometimes pansies survive under the snow, then begin to grow again the following spring. That's most likely to happen when we have a relatively mild winter combined with good snow cover.
Fall is also an excellent time to plant most trees and shrubs, especially conifers, which can sometimes suffer from heat and drought if they're planted in spring or summer. Try to get conifers into the ground by early October.
Mulch new conifers with about 3 inches of wood chips or shredded bark, applied in a circle covering the root area and beyond, if possible. Leave a little space for air circulation between the mulch and the conifers' trunks or stems. It's important to water conifers regularly until the ground freezes. A good layer of mulch will delay the soil from freezing and buy you a little time to water the plants and encourage root growth.
Fruit-bearing trees and shrubs fare better when planted in spring. Instead of planting apples, crabapples, pie cherries, plums, raspberries and blueberries, use this time to research which cultivars you'd like to try. Of course, if you run into a good bargain on a fruit tree this time of year, it might be worth taking a chance!
Deb Brown is a horticulturist with the University of Minnesota Extension Service Yard and Garden Line. For help with garden, plant and insect questions, call the Yard and Garden Line at 612-624-4771.