Fall and Winter Projects
by: Charlie Hartman
Idaho Certified Nurseryman
As the days get shorter and there’s a nip in the air, we know that autumn is quickly approaching.
If you have been in the Boise area for many years, you then know that our cold winters can be quite harsh on plants here in the valley and this is especially true of plants in containers. In part, this is because containers above the ground are subject to extreme temperatures, causing the soil to constantly thaw and freeze. If you have plants in containers that need to be wintered over, move them to an area of the yard that affords some protection from winter elements. Our best recommendation is to place them in a shrub bed and place mulch around the pots that is equal to the height at the top of the root system. We realize this is not always a possibility since some containers are extremely heavy. There are two options in such circumstances; one is to hire The Home & Garden Store to move your containers with a heavy-duty ball cart to an area of your yard or use styrofoam or roofing installation to wrap the container for winter protection. The drawback to wrapping them with either of these products is aesthetics. We don’t find these materials to be attractive however. Another option is wrapping the container with straw, but what do you do with the straw come spring and it’s not aesthetically pleasing either?
Do you have roses in the landscape? If so, remove all leaves around the plants to reduce the possibility of any diseases occurring in the spring. Wrap the union (sometimes called crown) of each plant with “Rose Guard” and fill with small or medium bark. Rose guards are a piece of plastic that is approximately four or five inches high and used to hold a product such as bark mulch in place to protect the union during cold winter months. Fill the rose guard with enough bark to completely cover the union on the rose. Never use soil or any material that does not allow the union to breathe. Remove the rose guard in mid-March. Rose guards can be used over and over again, so save them for future use. Applying Hi-Yield "Dormant Spray" in the fall once the plant has gone dormant and again the following spring will help prevent diseases from occurring.
If you have tree roses, remove plants from the soil and lay them down in late fall just before the soil freezes. Cover the root system with topsoil, and then cover the remaining plant with bark mulch to protect them from harsh winter conditions. If roses are in a container, an option is to place them in an unheated garage with windows and watering several times during the winter season to prevent the roots from drying.
We recommend placing bark mulch around deciduous trees for several reasons. One of the best reasons for doing so is that the string on weed and grass machines won’t get close to the tree bark and cause extensive damage to the trunk and perhaps kill the tree. Another reason is that it will provide some winter protection to the root system of trees. A great look to any landscape is to place a large boulder near a tree and wrap the tree with perennials or annuals.
As soon as the leaves start dropping in the fall and you have a pond, you will need to cover your pond to prevent decaying leaves from producing toxic gasses that may harm fish. Use a fish net and/or a skimmer unit to remove debris from the water. As late fall approaches, stop fertilizing aquatic plant material. Cut down foliage on hardy bog, water lilies, and marginal plants to approximately 2-3 inches from the pot just as you would perennials in the garden. Hardy water lilies require a period of dormancy and need to be left outdoors, however tropical water lilies must be brought indoors until spring. Tropical lilies can be left in water or placed in wet sand. Tropical's are somewhat difficult to maintain during the winter months and it’s sometimes best to treat them as annuals.
Potatoes are typically ready for harvest in mid-fall. You'll know when by watching the tops of the plant. As it begins to die back, think about harvesting. Potatoes can tolerate a light frost, but should be dug not long thereafter. Store them in a cool, dry place. Many gardeners harvest onions throughout the growing season, but fall digging requires that you place onions on a surface for several weeks to allow the tops to die back and the onion to form a slightly brownish layer to the outside skin. Temperatures should be around 32 degrees for best results. Onions typically keep for 2 or 3 months after digging and maintained properly. Vegetable plants such as horseradish can be harvested around mid-fall also. Leave a small root or two to ensure a bountiful harvest next year. About the same time, you may want to remove the remaining stalks from rhubarb plants as typically, the season is over in our part of the country.
Mid-fall is excellent for controlling perennial weeds. You may not think of dandelions as a perennial, but they can come back from the root, especially in mild winters. Spray them and other weeds with Ferti-lome 'Weed-Free Zone, the most effective weed killer for hard-to-kill weeds. There is one perennial that you should know that is nearly impossible to control. That's bindweed! We talk to many avid gardeners each year and they all say the same thing when it comes to bindweed. It is extremely hard to control. The best opportunity for controlling this perennial weed to continually spraying or pulling the weed out as soon as it breaks the soil surface. The roots are so deep on this plant that nothing seems to have a lasting control. Sooner of later, it seems to find a way back to the soil surface.
Wrap all smooth barked trees during the winter months with “Tree Wrap”. Over the years, we have seen a lot of winter-kill caused by the reflection of the sun off snow. It destroys the cambium layer of the bark, which in turn may kill a tree. Wrap in late September to mid-October and unwrap in mid-March. If you don’t unwrap a tree come spring, insects can lay eggs under the tree wrap and cause damage. By removing the wrap, it also allows the cambium layer to thicken and withstand our winter months as the tree matures.
Apply Ferti-lome “Horticultural Oil Spray” to all deciduous trees in late fall and again in the spring to suffocate insect eggs. An application must be enough to coat the insect’s eggs before they have the opportunity to hatch. Do not spray when temperatures may drop below freezing within six hours after application. Spray from the base of the tree to the first or second branch. Most insects lay their eggs in this area of the tree. Using a combination of Ferti-lome Horticultural Oil Spray (to suffocate insect eggs) and Ferti-lome Liquid Systemic Fungicide II (to control fungus) gives deciduous trees some protection. The entire tree must be sprayed with this product. Apply a combination of these two products, Ferti-lome “Broad Spectrum Landscape & Garden Fungicide” and Ferti-lome Horticultural Oil Spray. An application of lime-sulphur spray can be applied to stone fruits and their flowering cousins to control rust, scales, powdery mildew, and blister mites when necessary. Deciduous trees should be treated with Ferti-lome “Tree & Shrub Systemic Insect Drench" at least once a year. We prefer the fall for applying this product, but most any time of year will work. Just be sure to get it done or risk the chance of losing a valuable plant.
Are you planning on early spring color? Fall (late September to late October) is ideal for this project. We recommend planting bulbs in groups, using the same color of bulbs and variety of bulbs throughout the desired area. That doesn't mean you should only plant one type of bulb, but limit the varieties to two or possibly three types of bulbs. Fall is not only the time to plant spring flowering bulbs. Fall is a great time to plant garlic as well as many varieties of perennials such as garden mum's.
Leave your pruning of perennials till spring as this allows all nutrients to return to the root system. We typically recommend spring cleanup to occur around the 15th of March.
Fall is a great time to fertilize the lawn and landscape. We highly recommend Ferti-lome “Winterizer Fertilizer”. Doing so will yield an outstanding lawn and a beautiful, healthy looking landscape the following spring.
We can’t stress how important it is to heavily water the lawn and landscape as plants go into the winter months. Keep in mind that if you turn the water off in September as so many do here in the valley, that plant most likely won’t get watered again till spring. Sure it will snow at some point, but the ground will be frozen, allowing the moisture to run to the street and to the city gutter system. Start watering in early October. With deep roots on trees, we water at a trickle for 12 hours before moving the hose to the next tree. What I do at our home is move the water hose in the morning prior to going to work and then again when we get home. Although you can over-water in the spring and summer, it’s quite hard to over-water in the late fall to early winter. Be sure to put away your garden hoses as winter approaches. Leaving them connected to a faucet may damage the unit.