July 2015 Culture, Grower News, Plant Health, Production, Variety Info

Perennial Solutions: Lavandula Stoechas ‘Bandera Purple’ By Paul Pilon

With its aromatic herbal attributes and landscape presence, the demand for lavender continues to increase.

English lavender (Lavandula angustifolia) is the most commonly grown lavender, but Spanish lavender (Lavandula stoechas) has many uniquely appealing characteristics that sets it apart from others. They are known and easily recognized by their showy and more fragrant flowers.

Recently, Kieft Seeds made a breeding breakthrough and developed Lavandula stoechas ‘Bandera Purple’. It is the first commercially compact Spanish lavender from seed. It branches very well and produces an abundance of eye-catching blooms that nearly cover the attractive silver-green colored foliage. The flower spikes contain dark purple-violet flowers with beautiful purple flags (bracts) on top of the inflorescences.

Spanish lavender grows best in locations with full sun and can tolerate heat and humidity better than the other types of lavenders. With cold hardiness in Zones 7 to 10, some parts of the country will have to grow this one as an annual.

‘Bandera Purple’ forms attractive compact mounds reaching 7-9 inches tall and 10-12 inches across, which do not fall open with age. The showy, winged flower spikes appear in the late spring and last well into the summer. The flowers are self cleaning, and the plants produce a good secondary flush of fragrant blooms.

This small, yet floriferous lavender is suitable for production in small containers or combination pots and is often utilized in border and container plantings.

Other appealing attributes of interest to gardeners and landscapers, lavenders are not attractive to deer or rabbits, and once they are established, they are drought tolerant.

With its strong garden performance and desirable attributes, Lavandula stoechas ‘Bandera Purple’ received the Fleuroselect Gold Medal Winner in 2015.

Smalll yet floriferous, ‘Bandera Purple’ is suitable for small containers.

Propagation

‘Bandera Purple’ can easily be propagated from seed. Growers generally sow one seed per cell in 288- or 180-sized plug trays. Light is considered optional for germination; however, having some light present during this stage is
beneficial and will reduce early stretching of the seedlings. The seeds can be covered very lightly with vermiculite after sowing. Covering them too deeply will greatly decrease the germination rate.

If available, use a germination chamber to maintain temperatures of 65-68° F and the relative humidity at 95 percent. Keep the media moist, but not saturated until the roots emerge (level 4). To decrease early elongation, remove them from the chamber when 15 percent of the cells have radicles visible. Germination takes three to five days.

After the seeds have germinated, the temperature of the soil can be reduced slightly to 60-65° F; also reduce the soil moisture levels slightly (level 3 to 4) to encourage rooting. Fertilizers can be applied once the true leaves are present, applying 75- to 100-ppm nitrogen, using a nitrate-based formulation with low amounts of phosphorous. As the plants develop, the fertility rate can be increased to 100-150 ppm. Growth regulators are usually not necessary, but if toning is required, spray applications of 2,500-ppm daminozide (B-Nine or Dazide) can be applied. When produced at temperatures averaging 65° F, they are usually ready for transplanting in seven to eight weeks.

Attractive mounds reach 7-9 inches tall and 10-12 inches across.

Production

‘Bandera Purple’ is well suited for production in small 1-quart to 1-gallon sized containers. Spanish lavender performs best when they are grown in a porous, well-drained medium with a slightly acidic pH: 5.5-6.0. When planting, the growing medium should be even with the top of the liner. Avoid transplanting too deeply as Botrytis may develop on the branches that are in direct contact with the moist soil. Since they branch freely, it is not necessary to pinch prior to potting or during production.

Like most types of lavandula, Spanish lavender require an average to slightly below average amount of irrigation, as they do not tolerate really wet or overly dry conditions. When wet conditions persist for extended periods, they are very susceptible to root rots.

Keep in mind that while they are in containers they are not quite as drought tolerant as those grown in the landscape and should be kept slightly moist (level 3). Overly dry growing conditions can adversely affect the opening of the flowers. When irrigation is necessary, water them thoroughly then allow the growing mix to dry slightly between waterings.

Spanish lavender need light to moderate fertilization. Growers using
water-soluble fertilizers either apply 250 ppm of nitrogen as needed or feed with a constant liquid fertilization program using rates of 125- to 150-ppm nitrogen with every irrigation. Controlled-release fertilizers can also effectively deliver nutrients when incorporated into the growing medium prior to planting at a rate equivalent to 1.0 to 1.2 pounds of elemental nitrogen per yard of growing medium.

‘Bandera Purple’ has a naturally compact growth habit and usually will not require height control strategies. The plants can be toned using spray applications of 2,500-ppm daminozide (B-Nine or Dazide), 30-ppm paclobutrazol (Bonzi, Paczol, or Piccolo) or 5-ppm uniconazole (Concise or Sumagic). To improve plant quality, reduce stem elongation and avoid problems with plant pathogens, grow lavender with high light intensities and low relative humidity levels (< 75 percent).

Insects and Diseases

Although there are several insects which feed on lavandula, they can generally be grown without significant damage. Be on the lookout for aphids, leafhoppers, spider mites and whiteflies. Of these, aphids and whiteflies are the most prevalent. There are several diseases including bacterial leaf spots (Xanthomonas), Botrytis, fungal leaf spots (Colletotrichum and Septoria) and several root and crown rot pathogens (Fusarium, Phytophthora, Pythium, and Rhizoctonia) lavender are susceptible to. Routine scouting is useful and recommended to detect insect pests and plant diseases early, allowing the appropriate control strategies to be implemented before significant crop injury or mortality occurs.

Flower spikes contain dark purple-violet flowers with beautiful purple bracts on top of the inflorescences.

Temperature and Scheduling

Lavandula stoechas ‘Bandera Purple’ is a first year flowering tender perennial, which can be easily grown and scheduled to bloom during the first growing season. Vernalization is not required for flowering and over-wintering should be avoided altogether in colder parts of the country. It is recommended to use frost protection when the temperatures are below 39° F.

‘Bandera Purple’ is a facultative long day plant. This means that although it will flower under shorter day lengths, it blooms more uniformly and faster when it is grown with long day lengths (>14 hours). Growing them with short day lengths will increase the time to flower and reduce the total number of blooms each plant produces. To further improve plant quality and increase the number of flowers they produce, grow ‘Bandera Purple’ under high light intensities (> 4,000 foot-candles).

For the best plant quality with the largest flowers, grow Spanish lavender on the cool side with ideal temperatures of 54-60° F at night and 65-68° F during the day. At these temperatures, ‘Bandera Purple’ takes 11 to 15 weeks after transplanting to flower.

Availability

Lavandula stoechas ‘Bandera Purple’ is brought to the market by Kieft Seed (www.kieftseed.com). To obtain seed, contact your Ball Sales Representative (www.ballhort.com). Plug flats can also be obtained through your Ball sales representative or various reputable perennial plant brokers and propagators.