Fall into action
Fall is a great time to prepare annual and perennial beds for next year's growing season.
For many landscape professionals and grounds managers, autumn brings shorter days and a break from long summer hours. However, there are still plenty of chores you can perform in your color beds and perennial plantings that will help improve their performance next year.
Start from the ground up - Prepare your soil. Fall is an excellent time to prepare soil for annual color beds and perennial growth next spring. First, have the soil tested for pH and nutrient levels. This should be done a minimum of every 3 years. Many of the products used to alter pH and nutrient levels take 3 months or more to affect a change. An early start will ensure proper soil conditions when active plant growth resumes in the spring. Take the soil sample to your fertilizer supplier or state testing lab - if the recommendations are confusing, call them for an explanation. If some areas of the bed did not perform well, take a separate sample. The bed may have a localized deficiency, and the data may explain why a particular species didn't perform well. Perennial beds can be amended and improved in stages. Every time a plant is divided or a new plant installed, incorporate recommended amendments. Keep a ready supply of needed nutrients so you can remedy specific problems without overfertilizing. After perennial plants go dormant, apply a fertilizer with either a 3-1-1 or 3-1-2 ratio. If the plants are dormant, the tops will not grow, but the roots will absorb nutrients and store them for use in the spring. If the bed is severely deficient in one or more nutrients, plan to rehabilitate the entire bed.
In addition to adjusting nutrient levels, you should amend the soil with quality organic materials. Cotton bur, alfalfa and mushroom composts are a few that are commercially available. Because organic matter is constantly decomposing, annual additions are essential for maintaining desirable organic matter levels. If soil-borne diseases are a problem, add some type of compost to help suppress disease organisms. Turkey-litter compost and brewery sludge have both proven effective for preventing some diseases on golf-course greens. Putting their high biological activity to work may prove effective in your beds as well.
r Correct drainage problems. Not many annuals will tolerate poor soil aeration and porosity. Evaluate all beds for drainage problems and, if necessary, install drain tiles, regrade the bed or perform other activities to keep the soil drained. Some soils are too porous, and water rapidly drains through the root zone. The above-mentioned composts will help retain water and nutrients in overly-porous soil and increase porosity in heavy, wet soils. Also, consider water-saving (hydrophilic) gels. Talk with other professionals about their experiences with them. Many have had good results incorporating them into beds.
r Prevent salt buildup. If the beds are near sidewalks or driveways that require deicing, salt buildup is a concern. In addition to burning tender roots, some deicing products destroy soil structure and can prevent air and water from entering the rootzone. Incorporate gypsum in the top 6 to 12 inches of the soil. If the gypsum is in place prior to deicing, it may prevent soil structure damage. The amount of gypsum needed depends on the texture of the soil and the amount of deicing chemicals used. Experiment with rates as low as 10 to 20 pounds per 1,000 square feet, and increase applications until the desired result is achieved. Gypsum is a source of calcium and will not harm the roots. However, excessive amounts can disrupt the balance of other important nutrients. Try not to overdo it.
Prepare tender perennials You can dig cannas, caladiums, gladiolas, elephant ears and dahlias after frost kills the foliage and store them as directed by a reliable reference. Some need storage in dry sawdust while others prefer soil. Find out what works best in your area. In southern climates, you can leave these plants in the ground throughout the winter.
Purple fountain grass has become a popular accent for color beds. Unlike many ornamental grasses, it is not hardy anywhere colder than Zone 9. Dig the roots in the fall, divide them and provide minimal water. You should keep them in a greenhouse or storage area during winter.
You can also dig and store ornamental sweet-potato tubers for planting next spring. These vigorous plants are easily grown in containers or as a ground cover. Some common cultivars to try are `Ace of Spades' and `Blackie' (burgundy/dark purple foliage), `Margarita' (lime-green) and `Tricolor' (pink, cream and green foliage).
Plan perennial plantings r Map it out. If you don't have one, make a map of the perennial beds you maintain, especially if you added plants this year. Don't rely on your memory next spring. After many trips through the bed, it is still easy to forget where and how large each plant is. In the spring it will be easier to work around the plants if you know where they are. Note which plants are not performing and which are outgrowing their space. You should check several references to see if the site and maintenance level meet the needs of the plants. You may need to consider alternates. While creating or updating the map, look for plants that have reverted back to the species, such as ribbon grass or Arundo donax that are no longer variegated. Some variegated varieties have aggressive non variegated parents. Remove them to avoid problems in the future.
r Evaluate water use. Maintaining plantings during drought is easier if the plants are arranged according to their water requirements. Research the water demands of individual species in the beds. If species are mixed, rearrange and coordinate plants to make irrigation easier. If you don't want to rearrange the plants, eliminate those that are not compatible with the majority, and replace them with more compatible species.
While considering water demands, evaluate the irrigation system. Sometimes spray nozzles are blocked by dense plants that limit the effective watering radius, or soaker hoses are not adequately arranged to provide proper coverage to all plants. Also, irrigation systems may need to be adjusted for plantings that have been rearranged. You should be able to evaluate and adjust the irrigation without damaging the plants.
r Divide perennials. There are many perennials that you can divide in the fall thus reducing your workload for spring. You should research proper division timing. Divisions should have at least 5 growing points. Make sure they are large enough to make an appearance next spring. If the clump needs to stay intact, reduce its size by cutting out a wedge on the back side while it is still in the ground.
Ideally, you want to finish dividing perennials 4 weeks prior to the ground freezing so that the replanted divisions have enough time to grow some new roots. If you cannot divide them early enough, a heavy mulch will help insulate the plant. This will keep frost heave to a minimum so that the roots are not exposed to colder temperatures and dehydration.
r Use new plants. Fill in areas or replace poor performers with something else. It's easy to get stuck on a few species of plants that perform well. However, an abundance of perennial (and annual) plants may grow well in your beds. Incorporate new species wherever possible - they may be undiscovered treasures. Many containerized perennials can be planted anytime, and root growth will continue as long as the ground is not frozen.
r Prevent weeds. If creeping turfgrasses are invading your beds, install a vertical barrier, preferably one that is at least 12-inches deep. Barriers are effective against rhizomatous grasses, such as bluegrass, but won't prevent stoloniferous grasses like buffalograss from creeping into the bed.
r Prevent other pests. Cut and remove dead foliage and stems that make a good overwintering habitat for insects and disease organisms. Leave enough stubble so you can identify plant locations. Thin out disease-prone, spreading perennials such as ajuga. The increased air circulation around the plants will help prevent problems next spring. If slugs are a problem, lightly cultivate around the infested plants to expose the eggs to winter temperatures. Good sanitation won't eliminate all problems, but it can help to reduce them.
r Water thorougly. Water perennials well so they will be less likely to succumb to winter stresses. If rain or snow is insufficient, you should irrigate thoroughly to compensate by wetting the soil to a depth of 12 inches. Use a soil probe or long screwdriver to verify the depth of water penetration. Depending on soil temperature and precipitation, additional irrigation may be needed throughout the winter. If necessary, thoroughly irrigate the soil every 4 weeks.
Make final preparations r Mulch. Mulch is beneficial for both annual and perennial beds. The primary benefit to annual beds is aesthetics and erosion reduction. Choose a mulch that suits your needs and climate. Large chunks can be removed by winds and will float easier in heavy rains. Perennials benefit by moderating soil-temperature fluctuations and conserving moisture. Apply a 2- to 4-inch layer to perennial beds after a couple of hard freezes. If applied while the soil is too warm, the perennials may not go dormant. You should avoid piling too much mulch directly on top of the crown of the perennial because this could promote crown rot. Purchase your mulch from a reputable source that can provide a product that is free of weed seeds.
r Bulbs. After the planting beds are prepared and nutrient levels adjusted, install spring-flowering bulbs. Choose locations that are well-drained to avoid bulb rot. If deer are a problem, install some type of screen over (and maybe around and under) tulip and Crocus bulbs that will allow them to emerge next spring. Water the beds thoroughly after planting and again in 4 to 5 weeks if no precipitation has fallen. Without adequate water, few roots will grow and the result will be a poor spring showing.
Plant something other than tulips in some of your beds. Grape hyacinth, though small compared to tulips, provide long-lasting color. Fritillaria add regal beauty (and a skunky smell too, so site these carefully). Naturalize with some daffodils, Leucojum, Galanthus, Scilla or Crocus. Although daffodils' colors are still somewhat limited, more are available now than ever before.
r Containers. When cool weather arrives, you may need to move containers to a protected location. New container technologies provide some insulation, but they may not be enough for your climate. If the container is too heavy to move, try replacing some of the soil with inorganic soil amendments (such as those currently used on golf greens). They are lightweight and many have excellent nutrient-holding capacities, which should reduce the need for heavier composts. If the containers were not draining well this past season, excavate to discover why. Filter fabric that was installed in the bottom may be clogged, or a clay soil may have been used as a filler.
If your climate is warm enough, you can plant containers with pansies, ornamental kale or spring-flowering bulbs. While you're at it, plant pansies in some of your color beds. Your clients will be glad you did.
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