Gardening Resources
Fall Garden Chores
Remove Annuals from Gardens & ContainersThe average frost date around the Twin Cities is October 6th (before our climate change it used to be Sept 15th) and that marks when your tender annuals are frosted or begin to decline. It is an easy chore to pull them out of the ground (we many times have a trowel in one hand to facilitate this process). A more sustainable approach to their clean up however, is to cut off or rake away their unattractive foliage and leave their underground root masses so that can be turned into the earth next spring.
Annuals like Impatiens, Salvia or Potato Vine have such massive root systems that turning them back in to the ground, earth to earth, ashes to ashes, helps to replenish the nutrients that are taken out of the soil all summer long. Care needs to be taken to ensure that there is no disease in the debris that is left in your gardens. Traditionally we take annual roots out of containers, but again those masses can assist a spruce tips ability to stay in place until the soil freezes. If you do empty your containers completely recycle the potting soil into your garden beds. We suggest containers receive new potting medium every two years.
Reduce, Reuse and Recycle Tubers, Tropicals and Houseplants
Dig up elephant ear, canna and dahlia tubers to reuse next season. We have had success digging them up either before or after a frost. Wash off the soil, label them as to variety and place them in a crate of peat moss. The trickiest part of this process is locating a spot that is dark and 40 to 50 degrees all winter, like an old root cellar. They will need water once a month so they do not dry out completely. Start them in the greenhouse or sunny window in March or April to encourage bushy plants that can be installed after fear of frost has past.
Tropical plants that effectively go dormant in this same cool location include banana trees and Australian tree ferns. Simply cut back their foliage leaving the main stem, water sparingly once a month and they will sprout again next spring even bigger and better. So not only can you recycle these expensive plants but they will be even larger if you do.
Blooming tropicals like hibiscus, oleander or bougainvillea can live inside for the winter by a sunny window. The most important thing to remember is to hose them off well to remove any insects. We also prune them back in the winter to encourage new growth and water with a diluted fertilizer. We use many "houseplants" in our outdoor containers and these can be very easy to pot up in another container to over winter inside your home. Try placing by a sunny window your philodendron, palm, cordyline or ivy. This approach also reduces the input of debris to compost sites or landfills.
Perennial Clean Up in Spring or Fall
The removal of perennial foliage may be performed in the spring or in the fall. It is somewhat of an aesthetic preference. It is only necessary to clean up your garden in the fall when fungus or disease is present as you do not wish that to overwinter. Plants that may have diseased foliage or ones susceptible to fungus that should be removed include Peony, Phlox paniculata – Garden Phlox German Iris, Monarda, Roses and Tomatoes. You may wish to remove the foliage of those plants but leave everything else in tact.
Whenever clean up is performed always leave the evergreen foliage of Bergenia, Euonymous – Wintercreeper, Festuca – blue Fescue, Phlox subulata – Creeping Phlox, Vinca minor – Myrtle. Also, when cutting plants back, care should be taken to leave the crowns of Heuchera – Coral Bells. You should leave at least 2' on your Perovskia – Russian Sage also as you can stunt it if this semi woody plant is cut back too far.
The benefit of performing perennial clean up in the fall is that your chore is more complete to free time in the spring for other chores. Spring is such a busy season that gardeners should always attempt to tackle as many tasks as possible in the fall. A sustainable approach to fall clean up is to use a mulching mower on your green debris (only non-diseased debris) and place this home grown mulch on top of your garden soils. This will break down over time and ad humus to your soils. You can also do this with the leaves from your trees. This mulch is not to be confused with winter mulch to protect the plants from winter kill, nor does it replace summer mulch. This mulch is to improve soil structure and to reuse resources on site versus hauling in compost or other soil amendments.
The benefit of raking gardens clean in the spring vs. the fall is that there is less foliage to remove thus less carbon footprint is left as most of the foliage will have simply withered away over the winter. Other benefits for leaving foliage up are perennial seed pods look fantastic poking through the snow and feed the birds in the winter (that is if you did not dead head them during the growing season). Perennials to leave up for winter interest and wildlife include Astilbe, Bergenia, Chelone - Turtlehead, Echinacea - Coneflower, Liatris – Blazing Star, Perovskia – Russian Sage, Rudbeckia – Black Eyed Susan, Sedums and Grasses.
Pruning
Other plants to consider for winter interest are Hydrangea, Rose Hips, Red Twig Dogwood stems and Birch bark. We prune our Hydrangea in the spring so that we can enjoy both the paniculata and macrophylla varieties throughout the winter. Certain roses develop hips better than others but many times the last blooms of the summer are not deadheaded to encourage this fabulous winter color. When the shrub or tree has lost its leaves for the year, this is a good time to prune Ash, Aspen, Birch, Catalpa, Poplar and Willow. If you wish to prune an evergreen, consider recycling them by waiting until their branches can grace your winter hearth or holiday table.
Protecting Roses
There are many hardy roses available now that do not need winter protection but if you have hybrid teas, floribundas, grandifloras, miniature or old fashioned roses you will want to provide winter protection for them. I would not even consider using those styrofoam cones as they do not offer enough protection and are unsightly. Two methods that work reliably well are mounding with soil and the MN Tip Method. For any protection you should wait until several frosts have occurred to help the roses go dormant. Roses typically put out one last wonderful flush of bloom this time for year, so many times gardeners are not ready to say good bye to them until after a frost or two anyway. Mounding roses is fairly easy and would be the method of choice when the rose is planted in a small space and when you desire the least amount of effort. If you have had a rose for many years that you have been mounding, I would not switch to "tipping" as the feeder roots would not be accustomed to this and injury is more likely.
For the MN Tip Check out the University of Minnesota’s information.
Additional Fall Responsibilities
Continue watering your gardens until right before the ground freezes. In the Twin Cities that is typically the end of November or early December. It is especially important to irrigate any plant materials installed this season, ones recently transplanted, spring flowering bulbs just planted and all evergreens. Many times we do not remember that evergreens benefit from fall rains as they hold moisture in their needles over the winter. If Mother Nature does not help us out in the fall, especially after a drought summer, it is imperative that you water your evergreens as a sustainable BMP. It may take several years for the evergreens decline to become apparent, but decline they will.
It is suggested to ad bone meal or another root growth stimulator hi in phosphate for spring bloomers, i.e., peony, iris, tulips and daffodils, or rhododendron. These plants need to expand their energy growing up right away when the ground thaws, so it is important for them to spend their energy on root growth in the fall (bulbs also benefit from another application in the late spring when their foliage is dying back down into their bulb). When you clean your fireplace to get ready for more fires, recycle the old wood ash by placing it on your lilacs.
For more information on reusing this by-product check out this website www.emmitsburg.net
Fall can be a great time to create a clean edge on your garden borders. Either plastic edging, brick, stone or simply a clean cut between the turf and garden soil can improve the aesthetics of your landscape. When the ground is frozen, anywhere form the end of November to the middle of December, an application of winter mulch is suggested to help tender perennials over winter. The purpose of this application of salt marsh hay, weed free straw or your very own recycled leaves is to keep the ground frozen once it is frozen. The benefit of purchasing a straw or hay mulch is it tends not to blow around the way your leaves can. Leaves will not blow as much if some perennial stems are left up to help hold them in place or if they are wetted once before a frost.
If we do not receive enough snow cover and we get a warm stretch in the middle of the winter, perennials can begin to grow or heave out of the ground. When the cold comes back, these plants become susceptible to winter injury. It is best to wait until the ground is frozen for several reasons. Rodents may burrow in the warm home you just provided if the soil is still diggable. The possibility exists to smother or rot perennials that are not completely dormant. If it snows before your winter mulch is down, lay it down anyway. Many perennials are extremely hardy in our zone 4a climate and do not require this cover. Some folks would just as soon not risk it and cover everything always. Marginally hardy, zone 5 or newly installed perennials all benefit from a winter mulch laid 2-4" thick.
Plants that are traditionally susceptible to winter injury include Heuchera – Coral Bells, Dendranthemum – formerly Chrysanthemum. Leucanthemum – Daisies, Delphinium plus anything that blooms right away in the spring as they can begin to grow before it is time, signaled by that early sun and heat.
Empty your compost bin, if your compost is ready, while soils are dry. Compost should be laid on top of your garden 1-4" thick being careful not to bury perennials too deeply. Compost can simply remain like this, no-till gardening, or can be turned into your poor soils in the fall or in the spring to improve structure and add nutrient value. We prefer a fall soil prep as that is when you can see all of the perennial stems to ensure that you are not smothering them or digging them up before they have emerged. Another benefit of fall soil prep is that the soil is generally dryer than spring soils. You should never till wet soils as it encourages compaction. We suggest the traditional double digging method of soil amendment.
For more information on double digging go to: www.communitycrops.org
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