When NOT to Plant in Fall

Fall has long been considered to be the BEST time to plant because it allows the plant to become well established before the heat of the following summer. It’s the best time to plant most native plants. It’s the ideal time to plant most trees and shrubs. It’s a good time to plant many perennials. It’s the right time to plant many ground covers. It’s a great time to plant!

However, just because fall is often quoted as “the BEST time to plant” doesn’t mean it’s the best time to plant ALL plants in ALL situations.

Gardeners need to use some discretion and common sense when deciding when to plant. Gardeners may also want to consider frost tenderness, plant availability, practicality, location, elevation, water availability, and use common sense.

Frost Tender Plants

“Fall is the best time to plant. I’d like to plant citrus. Is this okay?”

Frost tender plants are one type of plant that should NOT be planted in the fall. Hold off planting citrus and other frost sensitive plants until springtime. Newly planted plants are more sensitive to frost than established plants so

it’s best to give tender plants a long season to mature before the first cold snap. The best time to plant citrus and other frost tender plants is early spring, after the danger of frost is over. Depending upon your climate zone, you may need to wait until mid to late spring to plant.

Perhaps obvious to long time gardeners, warm season vegetables and flowers such as tomatoes, peppers, green beans, corn, cucumbers, zucchini, marigolds, sunflowers, and others that are sensitive to cold temperatures make sure to wait until spring to plant these!

Fortunately, there are many cool season vegetables and flowers that can be grown in fall and winter. Just because the seeds are available on a nursery rack or seedlings are sitting on a shelf, doesn’t necessarily mean that it’s the right time to plant.

Fungal Diseases and Clay Soil

“I planted some perennial flowers last fall and they all died over the winter. What happened?”

Fall planting is a good way to prevent root rot of many native and other plants. When planted in the spring, many plants are vulnerable to fungi in the soil when it becomes warm and damp during the summer irrigation season. However, other plants, mainly non-woody perennials, may be susceptible to rot when planted in fall in some of the heavy clay soils that we have in Foothill and Valley gardens.

These plants are sensitive to fungal disease when the soil is cool and wet. To avoid this, amend soil with good quality compost and take care that the crown of the plant is at or above the soil level. Thus, avoid planting the crown too low. When planted correctly, even these plants benefit from fall planting, and grow more vigorously the following year.

Practical Considerations

“If fall is the best time to plant, why don’t nurseries have a better selection? The plants don’t seem as lush as in spring.”

There are many plants that are started in late spring and summer that are green and lush in the fall. However, a disadvantage to fall planting is that some gardeners may perceive that the selection and quality of certain plants may be lower in the fall. There may be fewer of certain plants to choose from. Some plants may seem tattered or cutback, or the roots may seem tight in the container.

Many nursery plants have been growing vigorously all summer and are nearing their seasonal rest as the days shorten. Many plants have bloomed and been cut back after flowering. Leaves have endured a long season of rain, wind, and hot sun and may have a more battered look than earlier in the season. Drought-tolerant plants may be dormant and scruffy looking. Roots have grown and often fill out the pots by the end of the growing season.

None of these should deter the gardener. Tattered looking plants will push new growth the following spring. Tight but healthy roots can be gently loosened or lightly scratched at planting time, if necessary. And gardeners who need a special plant or a specimen can shop early in the

season and then hold the plant in the container until the correct planting time.

“Fall is the best time to plant but I live in the countryside and don’t have irrigation water after October 15. What can I do?”

Another practical consideration is water. Fall planting is often recommended because the fall rains provide moisture to plants, encouraging root growth.

Ideally, fall planting should coincide with fall rains. But if rains are late, or light and don’t sufficiently saturate the soil, supplemental water will need to be provided. Newly planted trees and shrubs need to be kept moist until the roots have a chance to grow into the native soil.

Many rural residents in this region rely on seasonal irrigation water, which normally runs from mid-April through mid-October. If supplemental water through another source, such as the household well, is not available or inadequate in the event that natural rainfall is late or not sufficient, a gardener will need to plant at a time of year that allows for irrigation. Each garden is different, but water availability is definitely a consideration when deciding on the best time to plant.

Common Sense

“I have a Japanese maple that I’ve been growing in a pot. It’s getting root bound; it’s showing a lot of signs of stress! I want to plant it in a corner of my garden that receives filtered light. Should I leave it in the same pot until fall and then plant it? Or should I repot it into a larger pot now, and then plant it in the ground in the fall?”

Of course, fall planting is usually the IDEAL time to plant. However, sometimes common sense trumps the ideal. Generally, repotting into a larger container and then waiting to plant until fall makes sense. However, in this case, the tree is showing stress in its present situation, yet is being planted in a good location, one where it will have minimal stress in adapting and growing. Don’t keep a stressed tree in a tight container.

Gently correct any girdling roots, and provide sufficient moisture through the warm season and on into fall to give the roots a chance to grow into the surrounding soil.

Gardeners should use common sense and check both the condition of the plant and the new planting location when deciding what would be the best choice in each situation. There is abundant research that fall is the BEST planting season, but practical considerations and common sense are important also for gardening success. And the best part of fall planting is how nice it feels for the gardener.

Cool snappy mornings and warm balmy afternoons, set with a background of red, orange, and gold fall foliage. What could be nicer? Happy fall planting everyone!

References

Abiotic Disorders of Landscape Plants, A DiagnosticGuide. 2003. Costello, Laurence R., Edward J. Perry, Nelda P. Mattheny, J. Micael Henry and Pamela M. Geisel. University of California Agricultural and Natural Resources Publication 3420

California Master Gardener Handbook. 2002. Pittenger, Dennis R., University of California Agricultural and Natural Resources Publication 3382