Fall is for Planting
Guidelines for Renewing Landscapes
Submitted by: Harriett McMillan, CCNP, Echter’s Garden Center
Provided by: Colorado Nursery & Greenhouse Association (CNGA). Visit www.coloradonga.org for your gardening needs.
Autumn is a perfect time for landscape renewal. Moderate temperatures and warm soils are beneficial for establishing plantings of trees, shrubs, perennials and bulbs. There is no better time to put in a new perennial border or to add additional shrubbery or trees to your landscape. Here are the steps for success in fall gardening.
Whenever we plant in Colorado, take the time to amend the soil with compost. Soil amendment improves the texture of clay soil and improves drainage and moisture retention in either clay or sandy soils. The drier soils of autumn are less prone to compaction while working in the soil than it is in spring, when the climate is wetter; another advantage for planting in the fall.
Make sure that plants are well watered before beginning this will help avoid transplant stress. Perennials with excessive top growth should be reduced in size so their energy goes to the development of roots.
Trees and shrubs should be watered in thoroughly. Check the soil every few days for moisture by checking the soil next to the root ball to a depth of 6 to 8 inches. If the soil is moist, do not water. When the soil has dried, water thoroughly. As a rule, a thorough watering every 5 to 7 days is sufficient to establish new plantings.
Early fall, from mid-September through the end of October is an excellent time to make or remake a perennial bed or border. Bed renewal is a key project and for best results planning is important. The objective is to plant fresh plants where others have weakened or declined. It provides the opportunity to divide and rejuvenate crowded clumps of plants or to rearrange or transplant poorly placed plants.
Keep the project workable, undertaking about 10 to 20 feet of a bed or border at a time. Evaluate the bed, taking note of robust or flourishing plants and leaving them alone if possible. Avoid disturbing plants such as gas plant (Dictamnus), baby’s breath (Gypsophila), false indigo (Baptisia) and peonies (unless they are in need of moving or division). Begin by cutting back the foliage by half and then lifting the clumps of perennials, putting them in containers, boxes or plastic bags; place them in a cool shady spot and keep them moist. Spade the area, removing weeds. Add 2 inches of compost, a dusting of super phosphate and spade again to incorporate thoroughly. Rake the area smooth and recompose the plants in the garden.
As you renew beds and borders consider the following;
- Include perennials for each season for a succession of bloom.
- Assess heights, shapes, textures, flower and foliage color for contrast and interest.
- Consider the edging plants as well as the background plants.
- Vary the contour with structural form: rounded, bushy, erect, vertical, layered or irregular.
- Use individual kinds of plants in groups of three or more for best effect. Select some single specimen plants for use as focal points.
- Plant bulbs at this time in some spaces and plan for adding annuals as well.
Most perennials divide easily in the autumn. A good spading fork lifts the clumps from the soil without damaging roots. A good division will have several strong shoots with plenty of roots to support new growth.
Garden clean-up in the fall is every gardener’s choice. There are really no hard and fast rules but perhaps a few guidelines. Any foliage with powdery mildew or rust should be removed from the garden and discarded. As perennials finish flowering you may choose to remove the flowering stems down to the base foliage. This cleans up the plant and makes for a tidy appearance. The basal foliage should remain intact. It helps protect the crown of the plants and is often persistent or evergreen adding appeal into the winter. In many instances the seed head remains sturdy and architectural adding interest to an area even after the petals have fallen. The coneflowers (Echinaceae and Rudbeckia spp. are examples). It remains for the gardener to decide what is interesting and what is not in their individual situation. Ornamental grasses put on their best display in the fall and continue to make an impression through the winter.
Rose pruning should be deferred until spring. Prune only those canes that are so long that they are at risk for storm damage. Leave at least 3 to 4 feet of cane for the winter. Apply mulch to grafted roses in mid-November after the soils have cooled.
Remember to water into the fall. Trees, shrubs, perennials and your lawn will go through the winter in better condition if they are not in drought stress. This gardening season has thrown more than a few curve balls our way, but probably no more than most years. Each year is its own adventure and for me this is the best part of the gardening year. Reflect, refresh, renew – fall is the real New Year for your garden.
Other tips:
- Amend soil with compost when planting to improve drainage and moisture retention. Visit your local independent retailer for a selection of quality bagged composts as well as bulk compost. Adequate soil amendment is the best step to success in gardening, no matter the time of year.
- Water new plantings thoroughly using a root stimulator. Check the soil every few days for moisture by digging down next to the root ball to a depth of 6 to 8 inches. If the soil is still moist, do not water. When the soil has dried, water thoroughly again. As a rule, a thorough watering every 5 to 7 days is sufficient to establish new plantings.
- Applying a 3 to 4 inch layer of organic material such as compost or pine bark mulch will help soils to retain moisture.
- Newly planted trees need to be staked for stability. The stakes may be removed after one complete growing season.
- Tree wrap should be put on the trunks of young trees in November. The tree wrap protects the thin bark from the effects of sunscald, which is common due to alternating warm and cold temperatures and the light intensity of low rays of sun. Tree wrap should be removed from the tree in April. Young trees should be wrapped yearly until they develop their mature bark.
- Cut back excessive top growth of perennials when planting. This will help the plant to establish a stronger root system without having to sustain an excess of foliage and flower.
Take advantage of the cooler temperatures of autumn by planning and planting for the year ahead. Visit www.coloradonga.org to find a local independent retailer in your area. Remember, Fall is for Planting!