A l A b A m A A & m A n d A u b u r n u n i v e r s i t i e s

www.aces.edu

ANR-1312

Greenhouse Production of Bedding Plant Snapdragons

snapdragons (Antirrhinum majus) are enchanting and delightful flowers that have been enjoyed for centuries. these mediterranean natives have many

pleasing attributes, from their delectable fragrance to their full range of heights and colors. they are popular as bedding and container plants and as cut flowers. the upright flower shoots are covered with buds that open from bottom to top, providing brilliant color for an extended period of time. snapdragons perform best in the landscape in cool weather, and most cultivars can even tolerate a light frost. they tend to suffer in the summer heat of the southeastern united states, and, therefore, are typically used as fall or early spring annuals. snapdragons flower the best in full sun and well-drained soil enriched with organic matter. they range in size from 4 inches to 2 to 3 feet tall, depending on the cultivar. Flower colors range from white and yellow to orange, red, and purple to almost black. the only color missing is true blue.

Cultivarssnapdragons are classified by height into three

categories: dwarf, medium, and tall. dwarf plants grow to be 6 to 12 inches tall in a dense, bushy habitat and produce abundant flower shoots. these cultivars commonly are used in the landscape for border edging or in mixed containers. in greenhouse production, they are grown in 36-cell market packs or 4-inch pots. the medium-sized plants grow to be 12 to 24 inches tall and often are used as border fillers or as cut flowers. in greenhouse production, they are grown in 36-cell market packs or 4-inch or larger pots. tall cultivars have a dominant, single flower shoot, grow to be 24 to 48 inches tall, and mostly are used as cut flowers, but also may be used in the back of a border. these are not often grown for bedding application.

there also are trailing types of snapdragons often used in containers and hanging baskets. some of the best trailing snaps are the luminaire series. An unusual butterfly-type flower can be found in the bell and la bella series in which the conventional floral tube is flared at the end, giving the flower a more open appearance. because of the more recent introduction of dwarf and medium-sized plants, snapdragons have become more popular as bedding and edging plants than their more traditional roles of background and cut-flower plants. this publication will focus on snapdragons commonly grown for greenhouse

production in either market flats or containers and used primarily as bedding or flowering potted plants. series and cultivars of snapdragons for bedding plant and pot culture are in table 1.

Seed PropagationStage 1

snapdragon seeds are very small but readily germinate under proper conditions. seeds should be sown in 406-cell plug flats containing sterile germination media with medium moisture content and a pH between 5.5 and 5.8. A higher pH can cause iron deficiency in snapdragons. the substrate temperature should be kept between 64 and 68 degrees F; temperatures higher than 75 degrees F can delay germination. because snapdragon seedlings are

2 Alabama Cooperative extension system

very sensitive to high soluble salts, electrical conductivity (eC) should be less than 0.75 millimhos per centimeter (2:1 extraction method), and ammonium levels should be kept at less than 5 parts per million. light is necessary for germination of some cultivars; contact the seed supplier for specific cultivar recommendations. seeds of non-light-sensitive cultivars can be covered with a light layer of fine vermiculite to maintain adequate moisture levels next to the seed. radicle emergence can be expected within 4 to 8 days after sowing; when they begin to emerge, reduce moisture levels to encourage roots to penetrate the media, which should be moist but not saturated.

Stage 2After radicles emerge, remove flats from the seed

germination chamber, if used, and then reduce substrate moisture level. light levels should increase to 450 to 1,500 footcandles. Once a week, apply 50 to 75 parts per million nitrogen using a 15-0-15 fertilizer or other low ammonium fertilizer formulation. if possible, alternate fertilizer with clear water. maintain substrate temperatures between 65 and 70 degrees F, and dry the foliage before nightfall to prevent disease. maintain water alkalinity at 60 to100 parts per million and ammonium levels at less than 10 parts per million. this stage requires 7 to 14 days.

Stage 3lower soil temperatures to 62 to 65 degrees F by night,

and raise light levels to 1,000 to 2,500 footcandles. Allow flats to dry between irrigations, but avoid wilting. increase fertilizer to 100 to150 parts per million nitrogen weekly, alternating between 20-10-20 and 14-0-14 formulations. However, avoid ammonium-based fertilizer if growing below 65 degrees F. during this stage, supplement fertility with magnesium sulfate once or twice and occasionally leach them with clear water to reduce eC. if stretching might be a problem, apply A-rest 3 to 4 weeks after sowing at a rate of 10 parts per million. Fungicides can be applied at the lowest recommended rate to control Pythium, Rhizoctonia, and Thieleviopsis. this stage requires 14 to 21 days.

Trailing Cultivarstrailing snapdragons, such as the luminaire and

Playful series, are propagated vegetatively. the best trailing cultivars are patented; therefore, propagation by unlicensed propagators is illegal. Also, stock plants can carry a number of latent diseases and should be virus-indexed and maintained in a clean stock system. For these reasons, growers should buy unrooted cuttings or rooted liners.

if unrooted cuttings cannot be planted immediately, store them for no longer than 24 hours at 50 to 60 degrees F. stick cuttings in Oasis wedges or in a sterile medium with a pH of 5.6 to 5.8. media temperatures should be maintained at 68 to 72 degrees F with an air temperature of 75 to 80 degrees F during the day and 68 to 70 degrees F during the night. light levels should be maintained at 500

to 1,000 footcandles. removable shade is an easy method for adjusting light levels as cuttings mature. use intermittent mist to maintain humidity around cuttings; the frequency should be adjusted based on light levels and temperatures. Calluses should form in 5 to 7 days after sowing. Apply a foliar fertilization of 50 to 75 parts per million nitrogen using a 15-0-15 or similar fertilizer formulation as needed.

Cuttings are ready for root development once a callus has formed and 50 percent of the cuttings have differentiating root initials. substrate and air temperatures need to be maintained, and light levels should be increased to 1,000 to 2,000 footcandles. Fertilizer also can be increased to 100 to 150 parts per million nitrogen weekly by alternating 20-10-20 with 15-0-15. reduce the mist as roots form; roots should develop 7 to 14 days after sowing.

Harden cuttings for 7 days before transplant or sale by decreasing air temperatures to 75 to 80 F degrees during the day and 62 to 28 degrees F at night, and increase fertilization to twice weekly.

Growing Onthe key to producing appealing, sturdy snapdragons

is cool temperatures. Plants may be exposed to light frost if heat is unavailable, but the most economical crops are produced at cool temperatures. Full sun and sufficient ventilation will help keep stems strong, and plant height in market packs can be controlled if water and fertilizer are applied somewhat conservatively.

transplant the seedlings when roots easily hold the plug mass together and have two to three sets of true leaves; do this in a timely manner to avoid stunting growth. bedding snapdragons perform best if transplanted to 18- or 36-cell flats and also do well in 4-inch pots or in groups of three to five plants in a 1-gallon container. trailing snaps should be planted in 4-inch pots or in pairs in 6-inch pots. Four to five cuttings can be planted in a 10-inch hanging basket.

Choose a sterile media with a moderate initial fertilizer rate and a pH of 5.5 to 6.2. maintain high light levels at 5,000 to 6,000 footcandles because low light causes stretching, reduces flowering, and increases crop time.

temperatures should be 72 to 75 degrees F during the day and 62 to 65 degrees F at night. You may reduce night temperatures to 45 to 50 degrees F once plants establish to promote flowering. Once flowering begins, maintain night temperatures below 60 degrees F.

Apply fertilizer twice weekly at 150 to 200 parts per million nitrogen alternating between 20-10-20 and 15-0-15 formulations. reduce this rate when flower shoots begin to elongate to increase postharvest life. For trailing snaps, it is important to maintain fertilizer levels because low levels hinder plant branching.

Pinch trailing snaps once the roots reach the edge of the container. throughout the rest of production, shear plants to maintain shape. Four-inch pots require one pinch; 6-inch pots, two pinches; and 10-inch hanging baskets, two

Greenhouse Production of Bedding Plant Snapdragons 3

to three pinches. Also, pinch taller bedding snapdragons planted in larger pots to promote branching and multiple flower shoots.

Height control can be a problem in bedding plant snapdragons grown from seed. When grown under recommended cool temperatures and high light, growth retardants should not be necessary. if needed, apply A-rest as a 10 to 26 parts per million spray or b-nine as a 2,500 parts per million spray on snapdragon seedlings. some growers tank mix b-nine and Cycocel with 800 to 1,000 of each after transplanting. You also may use bonzi as a 60 to 90 parts per million spray or sumagic as a 25 to 50 parts per million spray to control the height of snapdragons, but they may delay flowering and can cause less uniform flowering.

SchedulingCrop production time varies depending on cultivar.

in general, plug crop time from seed to transplant is 5 to 6 weeks. dwarf types take 4 to 5 weeks from transplant to finish in market packs and 5 to 6 weeks in 4-inch pots. medium-sized types take 10 to 12 weeks from transplant to finish in 4-inch pots and 12 to 13 weeks in 6-inch pots.

Pests and Diseasessnapdragons have fewer problems than many other

bedding plant crops. Fungus gnats and shore fly larvae are the most common insects on seedlings. Aphids, mites, and thrips may injure mature plants. be careful when applying pesticides to snapdragons because some are known to cause damage to flowers; carefully read the label to avoid problems.

downy mildew, powdery mildew, Pythium, botrytis, rust, Phyllosticta blight, and Anthracnose are common fungal diseases on snapdragons. tomato spotted wilt virus and impatiens necrotic spot virus also can be problems on vegetatively propagated snapdragons. to help control foliar diseases, avoid wetting foliage. if overhead irrigation must be used, water early in the day to allow foliage to dry before nightfall.

TroubleshootingHigh pH can cause stunted or uneven seedling growth

or poor root development. Also, very high pH can cause boron deficiency. A high pH or a cool, wet substrate may cause interveinal chlorosis of immature leaves, resulting in reduced iron uptake. if the problem is high pH, spray the plants with iron sulfate at 33 ounces per 100 gallons of water. if the deficiency is caused by the cool, wet medium, dry the substrate and increase the temperature. symptoms should diminish within 3 to 4 days.

botrytis infection or chronically wet substrate can cause the plant to collapse. High nitrogen concentration, applying too much fertilizer under low light conditions, or low light and overwatering can cause excessive foliage growth. Foliage necrosis can be caused by high eC or by the plant drying out between irrigations. trailing snapdragons that do not branch properly may not be receiving enough light or were not properly fertilized during early growth stages.

4 Alabama Cooperative extension system

Series / cultivar2 Company source Gardenheight(inches)

Comments

bells series Goldsmith seeds 8 to 10 9 colors; butterfly-type flower; flowers longer in garden; strong, well-branched plants

Chimes series Goldsmith seeds 6 to 8 10 colors; full, bushy plants loaded with fragrant, colorful shoots

Coronette series s&G Flowers 20 to 24 9 colors; filler in garden or cut flower; withstand wind and rain

Crown series s&G Flowers 16 to 18 14 colors; fast branching; strong garden performance; mid-height color in the landscape

‘Floral Carpet mix’ benary seeds 8 16 inches wide; very uniform; free flowering; ideal for group plantings

‘Floral showers mix’ benary seeds 6 Wide, flat cushions; extremely early for flowering sales

‘Frosted Flames mix’ Harris seeds 12 Open pollinated mix; bright, rich colors; unusual white variegated leaves

Freesong series bodger seeds 14 to 18 12 colors; recommended for garden beds, cut flowers, and 4-inch pot production

Kim series Floranova 10 to 12 11 colors; branching habit; side shoots and flower with central shoot; for pots and landscape

la bella series Goldsmith seeds 18 to 22 6 colors; open butterfly-type flowers on strong, well-branched plants

liberty Classic series s&G Flowers 20 to 24 8 colors; sturdy flower shoots and uniform habit

luminaire series

(cutting)

ball FloraPlant trailing 6 colors; free-flowering, trailing plants for containers and baskets

‘magic Carpet mix’ bodger seeds 6 to 8 Compact non-hybrid mixture

montego series s&G Flowers 8 to 10 14 colors; early flowering dwarf; strong basal branching for a robust-like plant

Table 1. series and Cultivars of snapdragons for bedding Plant and Pot Culture in Greenhouse Production1

Rachel Creel, Graduate Associate, and J. Raymond Kessler, Assistant Professor, both at Auburn university

For more information, call your county extension office. look in your telephone directory under your county’s name to find the number.

issued in furtherance of Cooperative extension work in agriculture and home economics, Acts of may 8 and June 30, 1914, and other related acts, in cooperation with the u.s. department of Agriculture. the Alabama Cooperative extension system (Alabama A&m university and Auburn university) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

Web Only, New Feb 2007, Anr-1312

© 2007 by the Alabama Cooperative extension system. All rights reserved. ANR-1312

Palette series American takii 6 to 8 11 colors; uniform; early flower; well-branched

Playful series

(cutting)

ball FloraPlant 6 to 8 6 colors; well-suited to pot-tight 4-inch programs

‘Princess White with Purple eye’

American takii 10 to 12 striking bicolor flower; uniform flowering

snappy series Hemgenetics 6 to 8 6 colors; very uniform flower time across color range

snapshot series ball seed Co. 6 to 10 11 colors; bushy, compact plants with closely spaced flower on shoots

solstice series ball seed Co. 16 to 20 9 colors; quick-finish; flowers 30 to 60 days earlier under short days than other intermediate size, winter-flowering cultivars

sonnet series sakata seeds 12 10 colors; strong root system; sturdy branches; can take high winds without lodging

tahiti series s&G Flowers 8 to 10 14 colors; dwarf plant habit; flats and pots

1 this table is not exhaustive but includes series and cultivars widely available on the u.s. market.2 names enclosed in single quotes are single cultivars. names without quotes are series of cultivars.

Table 2. recommendations for tissue Analysis nutrient levels in snapdragon

Percent

n P K Ca mg s

3.80 0.30 to 0.50 2.00 to 3.00 1.00 to 1.50 0.84 0.46

Parts per million

Fe mn Zn Cu mo b

75 139 56 9 0.85 30

Adapted from mills and Jones, 1996.