April 2002

Producing Woody Cut Stems By Lane Greer and John M. Dole

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, andwoodies are no exception. The plants cost more initially, and, depending on thespecies grown, there is often a 3- to 5-year wait before the first harvest.However, some species, such as Caryopteris and butterfly bush, will producegood yields from small plants only one year after being transplanted.

Good woody cuts share many of the qualities of goodherbaceous cuts. Plants should grow quickly, bear numerous, long stems, have along 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 areused by woody cut growers. These include farmers' markets, pick-your-ownand retail florists. However, there are some differences. Many farmers'markets and most pick-your-own establishments are closed from late fall toearly spring, which is a great time for harvesting and selling many woody cutssuch as pussy willow. A few retail florists may not be interested in some woodycuts. Working with berried plants like Callicarpa, for instance, can bechallenging.

Site selection. Formany woody plants, the best locations are the same as for any crop: sunny,relatively flat land with fertile, well-drained soil. But there are manyexceptions to this rule. Hydrangeas, for instance, need to be grown in shade inmost parts of the country. Many woody plants can be grown on sloping or evenhilly land. Some woodies even demand less-fertile soil, such as Callicarpa.Luckily, land that is considered unsuitable for crop production may beappropriate 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 closelyspaced than the same plant grown in a landscape setting. For instance, therecommended spacing for most butterfly bush cultivars is four feet. In aproduction system, however, these same plants could be spaced as closely as twofeet apart within the row. Tight spacing can be used because the stems will becut before they can interfere with each other, and plants remain relativelysmall. Also, for some species, close spacing can increase stem length. For mostwoodies, plants are spaced between two and six feet apart.

One crucial aspect to consider when planting woodies is weedcontrol. Landscape fabric is a better choice than plastic because water filtersthrough it, and it also has a much longer lifespan than plastic. Landscapefabric should be laid before planting. Organic mulches may also be used eitherprior to or after planting. Pre- and post-emergent herbicides that areregistered for use on woody nursery plants can be applied as necessary. Growersmay adapt an orchard system and choose to plant grass or some other groundcoverin the aisles; the width between rows should be adequate for equipment such astractors or mowers.

Another consideration for new fields is soil preparation.Proper pH is important for nutrient uptake, so adding lime or sulfur to a fieldbefore planting may be necessary. A soil test ç will provide informationnot only on pH, but also on the levels of macro- and micronutrients. It isespecially important to supply adequate phosphorus when establishing a newplanting, 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 usingdivisions may be a good idea. With slow-growing species such as Ilex andViburnum, however, larger plants will need to be planted. Lilacs take at leastthree years to produce a crop, so starting with a larger plant decreases theamount of time spent waiting for that crop to mature. Choosing a mix of plantsthat 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. Ifthe primary sales venue is a farmer's market that closes in October, forinstance, then growing hollies for Christmas sales would not be the bestchoice. If selling to an upscale retail florist, a good mix might include bestsellers, such as hydrangeas, curly willows and hollies, along with some unusualcuts, such as beautyberry, crabapple and purple smokebush. If the market allowsfor it, use species that extend the season. Forced branches in spring, (seesidebar on page 13), berries in fall, fall foliage cuts and hollies forChristmas are great choices.

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

Harvest and Postharvest

Harvesting. What isthe proper stage of harvest for a woody cut? Species being grown for theirflowers follow many of the same rules as herbaceous cuts. However, woody cutsoften do not develop after harvest as well as herbaceous cuts, probably becausethe woody tissues do not take up water, sugar and preservatives as well asherbaceous cuts.

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

Postharvest. Generalrecommendations include using a preservative and splitting the stem ends for3-4 inches (rather than crushing the ends).

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

Air temperature is the most important factor affectingpostharvest flower quality and vase life. The temperature range for holdingmost species of temperate cut flowers is 32-39¡ F; higher temperaturespromote senescence. Initial water temperature is also important in extendingvase life. Placing stems in warm water (110-120¡ F) immediately afterharvest is recommended for two reasons: Preservatives dissolve more easily init, and warm water contains less oxygen, which can plug the cut stem with airbubbles.

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

Postharvest treatments can be divided into two broadcategories: pretreatments and holding solutions. Pretreatments and pulses areshort-term treatments (lasting 1-48 hours, but usually overnight) that areconducted 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 toprotect the flowers from ethylene damage. With pulses, the idea is to"load" the stems and leaves with a high concentration of sugar orfloral preservative to aid in flower development. A common pulse uses 10percent sugar and is applied overnight. Another effective floral preservativethat is pulsed is silver thiosulphate (STS). STS works by protecting planttissues from the effects of ethylene. 1-MCP (EthylBloc) is also effectiveagainst ethylene. In several studies, 1-MCP has proven as effective inextending vase life as STS for several cut flowers, including carnation,alstroemeria, snapdragon, stock, gypsophila and delphinium. 1-MCP may bepreferable to STS because it contains no silver, the disposal of which hascaused some environmental concern.

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

Regardless of recommendations, conduct your own postharvesttests. Recommendations from preservative suppliers, publications and other growersare great to start with, but each farm has unique water quality, productionmethods and handling procedures.

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

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

Forcing

Woody branches can be "forced" into bloom weeksahead of their natural bloom time. After the plants have met their dormancyrequirements, branches can be cut and brought indoors. Depending on the part ofthe country and the weather, most plants have satisfied their dormancyrequirements by February. However, waiting until closer to natural bloom time(4-6 weeks before outdoor flowering begins) may improve the ability to forcethe branches into flower. For best results, cut the branches on days whentemperatures are above freezing. The branches should have numerous buds thatare 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 thebranches to a warmer area (70-75¡ F). Forced branches can be an excellentsource of income during early spring.