Master Gardener: Hydrangea basics

I recently attended the Horticulture Day hosted by the U of MN at the Lamberton Outreach Center. One of the speakers was Jeff Farber, owner of the greenhouses in Marshall and Tracy. His topic was Hydrangeas. He had beautiful colored pictures to go along with his presentation, but I did try to take notes to share with you about one of my favorite plants. Here is a brief overview of the information about the different varieties of hydrangeas that he presented to us.

1. Arborescens – Annabelle blooms on new wood; prefers shade; round, softball like blooms; cut it off to ground in spring

a.) Grandiflora is a new improved variety; 4′-5′ tall & wide; zones 3-0; can grow in sun if good moisture & soil; it it is too hot the tips burn on leaves; the wind also causes tip burn on leaves

b.) Incredibal – supposed to be an improved variety with stronger stems

c.) Incredibal Mini – dwarf; pink without adding acid; 2 and ?’ – 3′ tall; cut down in spring

d.) Wee White – 2 and ?’ tall; big white flowers on strong stems

2. Paniculata – prefers full sun; flowers on new growth; cut to within a few inches from the ground; stems hardy & good to zone 4; Paniculata can be grafted to be tree form

a.) Pee Gee – flowers are white & fade to pink-rose shades; conical shaped flowers in mid-July; do not plant on north side; needs sun

b.) Tickled Pink – Hardy; 4-6′ tall and 5-6′ wide; blooms start out white & turn tan-pink

c.) Vanilla Strawberry – gets more pink; 5-7′ height; Can be in tree form

d.) Strawberry Sundae – Height of 4-5′; smaller than Vanilla Strawberry

e.) Limelight – 8’tall; dark green leaves; blooms white with lime green

f.) Little Lime – 3-5′ tall

g.) Quick Fire – 6-8′ tall; starts blooming white, turns pink-red; blooms earlier (late May and early June); Japanese Beetles rarely feed on it; needs full sun to part shade

h.) Little Quick Fire – 3-5′ height; doesn’t flop as bad as the tall version

3. Macrophyllia – part sun/shade; should have at least 5 hours of sun; flowers on old growth (except Endless Summer)

a.) Endless Summer – Have to add acid to get blue color (can use aluminum sulfate around base); it will be pink without acid flowers late; often dies back to the ground; not particularly hardy in zone 4; wilts on hot, sunny days

b.) Bloom Struck – zone 4-9; 3-4′ height; 4-5′ wide; mop-head flower; starts growing in June; has good heat tolerance; thick green leaves

c.) Twist & Shout (in Endless Summer line); doesn’t have many flowers; blooms late

d.) Moonstruck – not all it is advertised as; blooms late with few flowers

General Information: transplant when dormant in late fall or early spring: can cut back in the fall; but might have damage if exposed; none are deer or rabbit resistant; do not have to cut back, or can do selective cutting (1/3), or cut back totally; Iron makes the leaves darker green; Add iron to balanced fertilizer; hydrangeas like well-drained soil; not clay; not good as potted plants; but if you do have in a pot, mulch as high as you can in winter because they are really a zone 5 plant; fertilize in early spring; can use slow release fertilizer.