When is the Best Time to Plant for YOU?

Like catkin seeds on the wind, information about willows is scattered about. One of the more surprising (re)discoveries is this study that we’ve found, brought to us by the Natural Resources Conservation Service, from back in 2008. The site we originally found this on no longer exists, thus we’ve reproduced here it in it’s entirety. This is available in PDF form just send us as email at contactus@vermontwillownursery.com and we’ll share it.

We usually find ourselves with piles of clippings and such after the Fall harvest. Imagine our surprise that when after the snows melt those piles are trying to send down roots! Since then we’ve seen many instances where they do just fine throughout Winter. The following study was done in Aberdeen, ID, which is zone 5 as of 2024.

Based on our experience, your anecdotes, and now this data, we’ve expanded our Fall shipping season. This now includes most of the US! We do make exceptions for colder zones but stipulations apply so send an email if this applies to you. On to the study!

Derek Tilley, Range Conservationist, and J. Chris Hoag, Wetland Plant Ecologist, USDA –
Natural Resources Conservation Service, Plant Materials Center, Aberdeen, ID 83210

Introduction
The majority of riparian restoration and streambank bioengineering projects are installed in the
spring as soon as weather permits. There are a number of reasons why spring plantings are more
prevalent than fall plantings. There is the fear that fall collected cuttings may have been stressed
due to hot summer temperatures, reduced water availability, insects and disease prior to cutting.
Another reason is the idea that a cutting left on the tree over winter should be healthier than a
cutting taken off the tree and left in the frozen ground for six months. Another one is that the
cutting might rot during the wet dormant period. In some cases, most of the project planning
usually takes place during the “down time” over the winter months, and restorationists are eager
in the spring to get back outside as soon as possible.

Dormant fall planting of hardwood willow cuttings can be a very successful technique and
preferable in many instances. For the highest survival, the bottom of a cutting must be planted
into the lowest watertable which typically y occurs in the fall. Fall planting may occur over a
longer period of time and present a very long window of planting opportunity rather than the
short planting window in the spring. Another reason to plant in the fall is that the cuttings are
ready to start growing before the weeds get going in the spring. This is very important since in
most springs, the ground is still too wet to plant the cuttings with equipment before the weeds
start growing. In the past, we have recommended that the cuttings not be soaked in the fall, since
they will be sitting in the ground all winter and should be able to absorb enough moisture to
become fully hydrated by spring.

So which is better, fall planted cuttings or spring planted cuttings? Each season has its benefits
and drawbacks. Fall planting often means that the cuttings are on the streambank much earlier
than spring planted cuttings so some protection of the bank is possible when the spring runoff
occurs. Furthermore, some root growth often will occur before runoff which helps with bank
stability. To help increase fall planting establishment success, not only should the cuttings be
harvested after leaf drop but new evidence indicates that soaking on an average of XX days helps
to hydrate the cuttings before they are planted.
The benefits of pre-soaking willow and cottonwood cuttings prior to planting have been well
documented (Edwards and Kissock 1975; Krinard and Randall 1979; Pezeshki et al 2005; Tilley and Hoag 2007).

Pre-soaking dormant hardwood cuttings has been shown to improve survival,
increase vigor and cause greater production of roots and shoots. However, all studies have been
conducted in the spring and have examined pre-soaking followed by immediate planting in
laboratory or field conditions where plants can immediately begin growing after planting. A
literature review yielded no reports of tests evaluating the efficacy of soaking, followed by a fall-
dormant planting.

Methods
To determine whether fall pre-soaking would increase establishment success, we compared
cuttings planted in the fall following a 14 day pre-soaking treatment, to fall planted with no pre-
soaking, spring planted following 14 day pre-soak, and a non-soaked spring planted control. The
cuttings were grown in Conetainers in the Plant Material Center (PMC) nursery.
Twenty-five dormant cuttings of peachleaf willow and coyote willow from the PMC willow
cutting nursery were harvested on November 19, 2007. Peachleaf willow cuttings were 20 inches
long with a basal diameter of about ¾ inches and the coyote willow cuttings were 20 inches long
with a basal diameter of approximately ½ inches. Although we normally recommend using
cuttings ¾ inches or larger, the source location of the coyote willow did not have many cuttings
larger than ½ inch. The best, most vigorous stems were selected, and were smaller than
expected. All side branches and terminal tips were removed at the time of harvest.
The cuttings were placed vertically in 5 gallon buckets filled 16 inches deep with water with
80% of the cutting submersed. The buckets were then placed in cold-dark storage at 4ºC for 14 days prior to planting (November 26 to December 10). Plants not soaked were placed in cold-
dark storage at 4ºC until planting (fig 1).
We planted the soaked and non-soaked fall harvested cuttings on December 10, 2007 into 40
cubic inch Conetainers filled with a perlite/vermiculite mix and placed them outside (fig 2).

Cuttings for the spring treatments were harvested dormant on March 10, 2008 for peachleaf
willow and March 21, 2008 for the coyote willow. Peachleaf willow cuttings were 20 inches
long with a basal diameter of about ¾ inches and the coyote willow cuttings were 20 inches long
with a basal diameter of approximately ½ inches. On March 24, the spring harvested cuttings,
which were the same size as the fall cuttings were placed in 5 gallon buckets to soak. Non-
soaked spring-harvested cuttings remained in cold-dark storage. On April 7, 2008 we removed
the cuttings being soaked and planted all of the spring collected cuttings (soaked and non-
soaked) into 40 cubic inch Conetainers filled with the perlite/vermiculite mix.

After planting, all of the cuttings in Conetainers were partially submerged in an outdoor 4’ X 8’
X 1’ tank, so they could be watered equally via sub-surface irrigation (fig 3). We initially filled
the tank so that water rose 3 inches up the cones. Water levels were then manipulated to rise and
fall ensuring that we provided adequate moisture for sprouting and growth.

On May19 (42 days after spring planting) we evaluated percent survival then carefully removed
the peachleaf willow cuttings from their cones and washed the soil away from the roots. Roots
and shoots were removed, separated, and air dried for four days and then weighed.

The coyote willow cuttings were grown longer than the peachleaf willow due to differences in
growth rates. In order to have sufficient vegetation to accurately weigh, coyote willow cuttings
were harvested on June 16 (70 days after spring planting). Roots and shoots were removed,
separated, and air dried for eight days and then weighed on June 24.

Results

Peachleaf Willow
We had 100% survival from the peachleaf willow cuttings. Root and shoot production, however,
did show differences between treatments (fig 4). In terms of roots and shoots, the pre-soaked
cuttings harvested and planted in the fall had better root and shoot production than all other
treatments. The poorest producer of roots and shoots was the spring harvested cuttings that did
not receive a pre-soaking treatment. Unsoaked cuttings harvested and planted in the fall had root
and shoot production similar to spring harvested and planted cuttings that had been soaked. Also,
for fall and spring collected materials, soaked cuttings performed better than non-soaked cuttings
harvested and planted within the same season (e.g., fall soaked cuttings out performed fall
unsoaked cuttings, .spring soaked cuttings out performed spring unsoaked cuttings).

Coyote Willow
Two cuttings died in the fall soaked treatment of the coyote willow trial reducing survival to
92%. The reason for the cutting mortality isn’t known. All other cuttings from the three
remaining treatments survived. Despite the somewhat lower survival, fall harvested and pre-
soaked cuttings had significantly greater root production than the other treatments (fig 5). Similar
to the peachleaf willow trial, the pre-soaked cuttings had better root production than their non-
soaked counterparts. Shoot production for coyote willow was essentially the same for all
treatments.