August 2003

Avalanche Petunias By Jason Riley

The Avalanche series was the first trailing seed petunia tobe manageable on the bench, flower under short days and require less PGRapplications. Further, an unparalleled color range including two reds was, andstill is, the crowning jewel to this class.

Germination

Germinate pelleted seed at 70-75° F, uncovered. Expectgermination to occur approximately one week after sow, depending onenvironmental conditions. Move stage 2 plugs out of the germination chamber orhouse and into the greenhouse to under 30- to 50-percent shade, and maintain70° F night temperature. At stages 3 and 4, plugs will happily withstandrelatively high light levels as long as watering practices are monitoredclosely. Temperatures during stage 4 may be reduced to tone the plugs. Be waryof Botrytis outbreaks.

Avalanche plugs may be held for a period of time. Controlstretch with either B-nine or Bonzi at 1,500-2,500 ppm or 3-8 ppm (spray),respectively. Bonzi is especially effective and should be used by experiencedgrowers, as similar rates under varying environmental conditions may havedifferent results.

Growing on

Avalanche petunias are suitable for finishing in 4-inch potsto 12-inch hanging baskets for three primary reasons: 1) They are well behaved,yielding a much longer bench life; 2) they flower and sell very early; and 3)they are quite floriferous over the whole plant, not just at the terminal endsof lateral growth. Their well-mounded and full habit is particularly conduciveto premium hanging basket production. Each of these attributes makes for asuperior final product that will sell quickly, no matter the pot size.

Grow Avalanche on at 65-70° F day temperature and58-65° F night temperature. Avoid high day temperatures, as this will onlystimulate excessive stretch due to a high positive DIF. Average daily temperaturesmay be dropped closer to sell date to intensify flower colors, maintain orincrease flower size, and extend bench life.

Avalanche petunias are more behaved than other trailing seedpetunias but may still require PGR applications to tone and/or augment theirhabit. For 4-inch production, B-nine at 3,500-5,000 ppm may be applied 1-2times during the crop cycle depending on climate. Late applications of B-ninemay delay flowering by one week. Although it is generally not necessary forAvalanche petunias, Bonzi at a 10- to 30-ppm spray may also be applied oncevisible bud stage is achieved. PGR applications are usually not necessary forAvalanche basket production.

Avalanches aren’t particularly fussy. Maintain relativelylow EC levels (about 1.0 mmhos), and fertilize conservatively so as to limitexcessive growth. About 150-200 ppm nitrogen should suffice. Limit yourapplication of fertilizers high in ammonical or urea nitrogen, as this willonly stimulate quick, soft growth. Alternating 20-10-20 with 15-0-15 shouldyield good results. Maintain pH levels around 6.0.

Sow to transplant generally requires 5-6 weeks depending onyour climate. Flowering occurs quite early and is not an accurate barometer oftotal crop time, while weeks to fill out the final container is. For 4-inchpots, an additional 4-5 weeks from transplant are required for finishing. For10-inch hanging baskets at three plugs per pot and 12-inch baskets at fourplugs per pot, 5-7 weeks from transplant are required.

Pests/Diseases

Avalanches are generally insect free. Scout for occasionalwhitefly infestations and spray accordingly. As for diseases, Pythium poses theprimary threat. The best defenses against root diseases such as Pythium aregood watering practices. Allow soil to become moderately dry betweenirrigations. Subdue Maxx applied as a preventative or curative, generally workswell for Pythium control.

Avalanche is easy, quick, floriferous and versatile. It isalso a great choice for combination pots, where it won’t overwhelm accompanyingplants, only enhance them. Currently comprised of nine colors — Cherry,Lavender, Lilac, Pink, Red, Rose, Salmon Shades, Tropical Red and White –most any theme or color combination may be developed with the Avalanche.