Producing Woody Cut Stems

Enterprising cut flower growers are looking for new species and cultivars to provide their customers with different products and enhance sales. At the same time, upscale retail florists are discovering what European florists have known for years: Adding woody cuts to an arrangement can immediately add height and uniqueness. Woody cut branches are used not only for their flowers, but also for fruit, stems and foliage. In addition, woody plant species with decorative stems and berries can be harvested in the fall, winter and early spring when other field cuts are not available and provide growers with sales during the off-season. 

Of course, there are disadvantages to growing any crop, and woodies are no exception. The plants cost more initially, and, depending on the species grown, there is often a 3- to 5-year wait before the first harvest. However, some species, such as Caryopteris and butterfly bush, will produce good yields from small plants only one year after being transplanted.

Good woody cuts share many of the qualities of good herbaceous cuts. Plants should grow quickly, bear numerous, long stems, have a long vase life and produce over a long season. 

The Basics

Marketing channels. For the most part, the same marketing channels used by cut flower growers are used by woody cut growers. These include farmers’ markets, pick-your-own and retail florists. However, there are some differences. Many farmers’ markets and most pick-your-own establishments are closed from late fall to early spring, which is a great time for harvesting and selling many woody cuts such as pussy willow. A few retail florists may not be interested in some woody cuts. Working with berried plants like Callicarpa, for instance, can be challenging.

Site selection. For many woody plants, the best locations are the same as for any crop: sunny, relatively flat land with fertile, well-drained soil. But there are many exceptions to this rule. Hydrangeas, for instance, need to be grown in shade in most parts of the country. Many woody plants can be grown on sloping or even hilly land. Some woodies even demand less-fertile soil, such as Callicarpa. Luckily, land that is considered unsuitable for crop production may be appropriate for production of some woody cuts.

Production systems. Production systems vary widely among land types, irrigation types and species. In general, however, woody plants used for cutting can be grown more closely spaced than the same plant grown in a landscape setting. For instance, the recommended spacing for most butterfly bush cultivars is four feet. In a production system, however, these same plants could be spaced as closely as two feet apart within the row. Tight spacing can be used because the stems will be cut before they can interfere with each other, and plants remain relatively small. Also, for some species, close spacing can increase stem length. For most woodies, plants are spaced between two and six feet apart.

One crucial aspect to consider when planting woodies is weed control. Landscape fabric is a better choice than plastic because water filters through it, and it also has a much longer lifespan than plastic. Landscape fabric should be laid before planting. Organic mulches may also be used either prior to or after planting. Pre- and post-emergent herbicides that are registered for use on woody nursery plants can be applied as necessary. Growers may adapt an orchard system and choose to plant grass or some other groundcover in the aisles; the width between rows should be adequate for equipment such as tractors or mowers.

Another consideration for new fields is soil preparation. Proper pH is important for nutrient uptake, so adding lime or sulfur to a field before planting may be necessary. A soil test Á will provide information not only on pH, but also on the levels of macro- and micronutrients. It is especially important to supply adequate phosphorus when establishing a new planting, since phosphorus is not very mobile in the soil.

Field establishment. Initial plant size will depend on the growth rate of the species. Forsythia, for instance, grows very quickly, so purchasing very small plants or using divisions may be a good idea. With slow-growing species such as Ilex and Viburnum, however, larger plants will need to be planted. Lilacs take at least three years to produce a crop, so starting with a larger plant decreases the amount of time spent waiting for that crop to mature. Choosing a mix of plants that will provide both immediate and long-term yields is best for most growers (see Table 1, right). The buyer will also dictate which species are grown. If the primary sales venue is a farmer’s market that closes in October, for instance, then growing hollies for Christmas sales would not be the best choice. If selling to an upscale retail florist, a good mix might include best sellers, such as hydrangeas, curly willows and hollies, along with some unusual cuts, such as beautyberry, crabapple and purple smokebush. If the market allows for it, use species that extend the season. Forced branches in spring, (see sidebar on page 13), berries in fall, fall foliage cuts and hollies for Christmas are great choices.

Select multi-trunked specimens and low-branching young plants. Prune the apical stem to get more branching. Well-branched plants will provide higher yields.  Furthermore, hard pruning encourages long branches on many species and reduces the height of tall-growing species, such as corkscrew willow.

Harvest and Postharvest

Harvesting. What is the proper stage of harvest for a woody cut? Species being grown for their flowers follow many of the same rules as herbaceous cuts. However, woody cuts often do not develop after harvest as well as herbaceous cuts, probably because the woody tissues do not take up water, sugar and preservatives as well as herbaceous cuts. 

Cut woody stems need to be at least as long as herbaceous stems — a minimum of 18 inches. Often, however, woodies are used in very large displays, so they can be quite large, up to seven feet long. 

Postharvest. General recommendations include using a preservative and splitting the stem ends for 3-4 inches (rather than crushing the ends).

Woody cuts can last much longer than herbaceous cuts. For example, Buxus sempervirens and Ilex crenata lasted 6-7 weeks in our work. Á

Air temperature is the most important factor affecting postharvest flower quality and vase life. The temperature range for holding most species of temperate cut flowers is 32-39° F; higher temperatures promote senescence. Initial water temperature is also important in extending vase life. Placing stems in warm water (110-120° F) immediately after harvest is recommended for two reasons: Preservatives dissolve more easily in it, and warm water contains less oxygen, which can plug the cut stem with air bubbles.

Although many cuts can be stored wet or dry, dry storage can shorten vase life. Preliminary research at North Carolina State University has indicated that dry storage under lighted conditions shortens the vase life of Buxus sempervirens. In wet storage, water quality is important to vase life. Water containing high levels of salinity, sodium or fluoride damages cuts. Low pH (between 3.0 and 4.0) is recommended for long vase life.

Postharvest treatments can be divided into two broad categories: pretreatments and holding solutions. Pretreatments and pulses are short-term treatments (lasting 1-48 hours, but usually overnight) that are conducted just after harvest. There are several goals in using pretreatments. One is to maximize the amount of water taken up by the stem, another is to protect the flowers from ethylene damage. With pulses, the idea is to “load” the stems and leaves with a high concentration of sugar or floral preservative to aid in flower development. A common pulse uses 10 percent sugar and is applied overnight. Another effective floral preservative that is pulsed is silver thiosulphate (STS). STS works by protecting plant tissues from the effects of ethylene. 1-MCP (EthylBloc) is also effective against ethylene. In several studies, 1-MCP has proven as effective in extending vase life as STS for several cut flowers, including carnation, alstroemeria, snapdragon, stock, gypsophila and delphinium. 1-MCP may be preferable to STS because it contains no silver, the disposal of which has caused some environmental concern.

Long-term or holding solutions contain an acidifer (usually citric acid at 350-500 ppm), sucrose (1-2 percent) and a biocide. In our research, however, adding sucrose at 2 or 4 percent has proven detrimental to vase life on Buxus sempervirens. 

Regardless of recommendations, conduct your own postharvest tests. Recommendations from preservative suppliers, publications and other growers are great to start with, but each farm has unique water quality, production methods and handling procedures.

Knowing the postharvest qualities of your cut flowers will allow you to adjust your cultural procedures to improve postharvest longevity. In-house postharvest testing is also valuable in handling complaints and providing your customers with current postharvest information. A postharvest testing system does not need to be elaborate and should take only a few minutes to set up and monitor each day. In fact, the simpler the system, the more consistent and useful the results are likely to be.

In setting up a testing system, collect and clean a number of bottles or inexpensive vases. For a new species, the easiest test is to place half of the flowers in untreated water and the other half in water plus your standard preservative. For current crops, you may want to test one or more new preservatives and handling methods. With any test, be sure to leave a few stems untreated to compare with your treated stems.

Forcing

Woody branches can be “forced” into bloom weeks ahead of their natural bloom time. After the plants have met their dormancy requirements, branches can be cut and brought indoors. Depending on the part of the country and the weather, most plants have satisfied their dormancy requirements by February. However, waiting until closer to natural bloom time (4-6 weeks before outdoor flowering begins) may improve the ability to force the branches into flower. For best results, cut the branches on days when temperatures are above freezing. The branches should have numerous buds that are slightly swollen. After cutting, put the branches into warm water (110° F) containing a floral preservative and place them in a cool area (50-60° F) with high humidity. After a week or two, either warm the room or move the branches to a warmer area (70-75° F). Forced branches can be an excellent source of income during early spring.