Growing hardy hibiscus in kentucky

Growing Hardy Hibiscus In Kentucky Dennis Morgeson Agent for Horticulture Washington County

Hibiscus • Includes a wide variety of plants grown for ornamental value, fiber, and vegetables • Several hundred species in the family Malvaceae (Mallow) • Related species include hollyhock and okra • Ranges from hardy perennials, annuals, shrubs, and tropical plants • We will concentrate on hardy hibiscus for Kentucky’s climate

Kentucky Native • Hibiscus moscheutos – Swamp Rose Mallow • Found throughout the Eastern United States in wet sites • Blooms up to 4” across and can grow up to 7 feet tall

Kentucky Native • Hibiscus laevis – Halberd-Leaved Rose Mallow • Again prefers wet or moist sites grows 3-6 feet tall and has 6” pink flowers • Native to the Eastern United States • Hardy in zones 4-9

Kentucky Native • Hibiscus palustris – Swamp Rose Mallow • Native to the Eastern United States • Prefers moist sites, grows 4 feet tall with 5-6” pink flowers • Hardy zones 4-9

Kentucky Native • Hibiscus coccineus – Scarlet Rose Mallow • Native to the South Eastern United States, hardy zones 6-9 • Again native to wet sites, grows up to 7 feet tall with 5” scarlet flowers

Natives • Hibiscus grandifloras – Large Swamp Mallow • Native to gulf coast states in brackish swamps • Grows 8 feet tall, hardy zones 6-9, with 10” light pink flowers • Has velvety leaves

Mature Height/Spread • New dwarf varieties grow only 23 feet tall • Others can grow up to 8 feet or more • Young plants are generally narrower than tall, but when mature clumps will be as wide as they are tall • It all depends on variety

Growth Rate • Most plants reach mature size in 23 years and remain that size for decades • Best growth occurs with ample moisture and fertile soil • Most varieties are capable of blooming the first year even from seed if started early

Ornamental Features • Generally grown for their large flamboyant flowers, however new varieties have added interest with leaf color as well • Hardy hibiscus gives a big bold tropical look to perennial borders during the heat of the summer when many prennials are spent • Attracts hummingbirds, butterflies, and bees

Culture • Most native hardy hibiscus are native to parts of Kentucky with the new varieties being very well suited to our climate as well • They prefer full sun and well drained soil with plenty of organic matter • They are tough and will tolerate part shade and poor drier soils but will not perform as well

Culture

• Hibiscus prefer plenty of water if abundant bloom is wanted • Water thoroughly and deeply but allow time to dry between waterings on established plantings • Newly planted hibiscus should be given more frequent watering like any other newly planted perennial would require • The native species will actually tolerate continuously wet conditions while new hybrids should be allowed to dry out

Culture • Tall hibiscus should be sited where they are not exposed to high winds to avoid breakage of the long stems • Staking is an option as well • Stems can be pinched when they are a couple feet tall to encourage branching and more flowering • New varieties generally bloom continually and older varieties can be pruned after the first flush of blooms to encourage regrowth and blooming

Propagation • Hibiscus are easily propagated by divisions, cuttings, and depending on variety seed

Division-Mid March to Early April • Step 1 • Dig a wide circle around your shrub, at least six inches from the base. That will penetrate some of the roots, but that is expected. The size of your hardy hibiscus will determine how deep you need to dig. It's better to go too deep, so start off a couple inches deeper than you originally planned.

• Step 2 • Lift the shrub out of its hole. Lay it on its side and think about how you're going to divide your plant. Separate the shrub into smaller clumps or larger clumps. Just be sure you get some roots with each clump.

Division-Mid March to Early April • Step 3 • Divide the bush with your hands. You may need an axe or saw to cut through the roots. The divided shrubs are now ready to give away or replant.

• Step 4 • Plant your new bushes as soon as possible (keep the roots moist in the meantime) to the same depth they were planted originally. Hardy hibiscuses prefer full sun and can tolerate most soil conditions. They do however, prefer soil that is well draining, so consider adding a couple inches of organic matter, such as compost or peat moss, to the soil before planting.

Cuttings-Anytime New Growth Is Available •1 • Measure out 1 cup of coir or peat moss.

Place it in a bowl. Pour water onto it until it is barely covered. Soak the coir or peat until it swells slightly and feels completely saturated.

Remove it from the bowl and wring out the excess moisture.

•2 • Combine the soaked coir or peat with 3 cups of medium-grit sand. Pack the mixture into a 4-inch plastic pot. Poke a 3-inch-deep hole in the center of the mixture. Set the pot in a shady location while gathering the hardy hibiscus cutting.

Cuttings-Anytime New Growth is Available •3 • Gather a 5- to 6-inch-long tip cutting from the hardy hibiscus. Choose one with a 1/4inch diameter, plenty of leaves at the tip and no flower buds. Sever the cutting 1/4 inch below a set of leaves using pruning shears or sharp scissors.

•4 • Remove the leaves along the bottom half of the hardy hibiscus cutting. Insert the leafless end into the planting hole created in the pot of soil. Press the sand mixture in against the stem to hold it steadily upright.

Cuttings-Anytime New Growth is Available •5 • Place the potted hardy hibiscus cutting in a sheltered location away from direct sun, salt spray and strong, drying winds. Choose a spot with dappled shade and good air circulation to prevent damage to the cutting. A grow light would be good too, but cover with a plastic bag.

•6 • Maintain light moisture in the coir and sand mixture at all times.

Allow only the top 1/4 inch of the mixture to dry out between waterings. Avoid saturating the soil during the rooting process since the cutting can rot.

Cuttings-Anytime New Growth Is Available •7 • Check for roots in four to five weeks.

Transplant the rooted hardy hibiscus cutting into a larger container filled with potting soil or directly into the garden one week after it roots. Keep it well watered for the first summer to prevent dehydration.

Seeding-Start Indoors or After Spring Frost Date • Not all varieties will produce seed, those that do may not come back true to seed • Seed can be sown indoors 12 weeks before the last spring frost. Soak seeds in very warm water for one hour before sowing. Seed can also be sown in place outdoors after the last expected frost date or fresh seed can be sown in fall.

Collect seed for fall sowing once the papery seed capsules brown and start to split. Plants often bloom from seed in their first year and will often self seed in suitable soil conditions.

Problems-Diseases • Common fungal diseases include root rots, collar rots, and botrytis blight.

Also susceptible to leaf spot diseases.

• These diseases aren’t prevalent and generally don’t warrant control • Sanitation is the key • If needed Immunox, Chlorothalonil, etc.

Problems-Insects • Insects are much more of a problem on hardy hibiscus than diseases • Aphids, whiteflies (generally greenhouse pest), Japanese beetles, hibiscus sawfly.

• Sevin, Malathion, Insecticidal soap, Orthene,

Variety!!!!

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You Get One of Each of The Following Mocha Moon (PPAF) A stunning combination of red eyed, creamy white flowers and very dark, bronze green foliage. Bright green carpels hold the 7 to 8 inch blooms and add another element of interest. Grows 4 feet tall and 5 1/2 to 6 feet wide.

Midnight Marvel A colorful specimen hibiscus for small gardens.

Plants are compact, growing only 4 ft. tall and wide. Beautiful, dark maple-like foliage highlights the platter-sized blooms and deepens further to vivid purple in full sun. Scarlet-red flowers open from black-red buds, adding drama to the eye-catching display. A fantastic plant from midsummer to fall.

Summer Storm

(P.P. 20443) One of the longest bloomers. Loads of 8 to 10 inch pink blooms accented with rose veins and magenta eyes are displayed against fantastic wine-purple foliage. 3-4 feet

Mars Madness • Zones 4 to 9 • Unique color combination of olive-green foliage and cerise-red flowers; manageable height but wide, spreading foliage makes this hibiscus a great choice for landscapers • 4 to 4.5’ tall by 6 to 6.5’ wide; finishes • quickly—6 to 8 weeks, 14 weeks to flower • Full sun to light shade; average to consistent • moisture—do not let plants dry out • Diseases are rare; common pests are Japanese • beetles, sawflies, spider mites, whiteflies

Tie Dye Hibiscus 'Tie Dye' is a new perennial mallow release from the breeding program at Walters Gardens. This lovely hibiscus produces 5' tall stalks adorned with large 10" flowers all summer...pink on the outer half of the flower face and white on the inner half...all accented by a central cherry-red eye. Moist soils are best, but Hibiscus 'Tie Dye' will prosper in all but the driest of garden soils.

Cranberry Crush • • • • • • • • • •

Duration: Perennial Height Category: Tall Garden Height: 36 - 48 Inches Spacing: 48 - 60 Inches Spread: 48 - 60 Inches Flower Colors: Red Flower Shade: Red Foliage Colors: Green Foliage Shade: Light Green Habit: Upright

Questions?