Garden Myths - Learn the truth about gardening

Hardiness of Liriope ‘Super Blue’

GardenMyths.com was contacted by Formostco Inc to trial one of their new plants, Liriope ‘Super Blue’. They wanted to know if the plant was hardy in our area (Zone 5b). This blog entry will be used to track out experience with the plants.

Liriope ‘Super Blue’

Liriope ‘Super Blue’

Garden Myths and Aspen Grove Gardens

Aspen Grove Gardens is the largest private garden in Guelph, Ontario. It was started around 2004 by Robert Pavlis and consists of 5.5 acres, specializing in perennials, shrubs and small trees. It now contains over 3,000 varieties of plants.

With a strong interest in horticulture, Robert started the blog GardenMyths.com to help educate gardeners about the truths in gardening. Aspen Grove Gardens is used as a test site for growing plants and as a source of garden pictures.

Formostco Inc

Formostco is a global leader in providing plant material for the nursery industry. As part of their goal to introduce new plants to the market it is important for them to test the plants in various environmental conditions.

Liriope ‘Super Blue’

Liriope ‘Super Blue’ is a selection of Liriope ‘Big Blue’ that is reported to be more vigorous and grow taller than Big Blue. Liriope ‘Super Blue’ should attain a height of 2 feet and it is currently reported to be hardy to zone 6.

Liriope plants are generally hardy in zone 6. In zone 5 some plants grow quite well and others have trouble overwintering. Since zone 5 represents a large part of the North American market it is important for companies like Formostco to understand the hardiness of their plants in colder zones.

Experiment design

In September of 2013 Formostco provided 12 plants of Liriope ‘Super Blue’ to Aspen Grove Gardens. They asked that the plants be grown in a variety of soil and light conditions. They also suggested that we treat plants in one of two ways; either cut back foliage in fall or leave it alone.

The plants were planted, before the end of September 2013, in a variety of conditions as described below.

The flower beds are mulched with 2-3 inches of wood chips but no mulch is used in the maple forest. Except as mentioned the plants were not treated any differently than the rest of the garden. It is our practice in fall to do very little to protect plants over the winter – in fact we don’t really do anything. All plant material is left to die down naturally in fall. Leaves may or may not blow in from surrounding trees.  No plants are covered. In summer gardens are rarely watered and except for degrading mulch they are not fertilized. Plants are expected to survive on their own.

Fall of 2013 was fairly wet with rains at least once a week through all of October. It was also a warmer fall than usual with the first real frost (pond has ice in the morning) coming November 3. We generally get a good frost early in October, followed by a warmer spell. Both the warmth and the rain should have provided the Liriope plants time to settle in before winter.

The following table describes the planting locations for the test subjects.

Identifier

Location

Cut back in fall
SB1 Bed A, full sun No
SB2 Bed A, full sun Yes
SB3 Nursery Bed, full sun No
SB4 Nursery Bed, full sun Yes
SB5

Nursery Bed, full sun, in pot above ground

No
SB6 Bed AD, shade No
SB7 Bed AD, shade Yes
SB8 Maple woods, very shady No
SB9 Maple woods, very shady Yes
SB10 Bed U, full sun, very sandy No
SB11 Bed U, full sun, very sandy Yes
SB12 Bed Z, bog garden that stays wet all year No

Notes:

(1)    SB1 and SB 2 are planted right next to Liriope ‘Majestic’, which grows well, but rarely flowers before fall frost.

(2)    SB5 was left in a pot above ground level. If this plant survives the winter it is definitely hardy in zone 5.

(3)    SB8 and SB9 will naturally get covered with sugar maple leaves for the winter. This should help survival provided that the crowns do not rot in the wetter conditions.

(4)    the nursery bed is similar to other beds, except that it gets watered as needed since it contains many smaller seedlings and new plants.

(5)    Soil is generally clay loam (40% clay), except as noted.

Results on November 4

This is the day after the first real frost. All plants are green and seem unaffected by the frost.

Identifier Comment
SB1 Growing well
SB2 Growing well, even though it was cut back
SB3 Growing well, nibbled by deer
SB4 Growing well, nibbled by deer
SB5 Growing well, nibbled by deer
SB6 Growing well
SB7 Growing well, even though it was cut back
SB8 Growing well
SB9 Growing well, even though it was cut back
SB10 Growing well, nibbled by deer
SB11 Growing well, nibbled by deer
SB12 Growing well, nibbled by deer

Liriope ‘Super Blue’ is reported to be resistant to deer on at least one web site. We don’t see a lot of deer damage in the garden except in late fall and early spring. Even at these times of the year the deer are fairly selective and only eat a few types of plants – Liriope ‘Super Blue’ seems to be one of them.

Results on June 7, 2014

Winter of 2013-2014 was unusual. The cold arrived mid December and it stayed cold for 3 months with almost no warming. Normally the cold does not start until end of December, and most weeks are reasonably mild–for zone 5. When cold does come it usually only last a couple of days to at most a week.

Because of the continual cold, the snow never melted. We had good snow cover all winter. That is very unusual since most winters have very poor snow cover. The warm spells always melt the snow.

On the coldest day we reached -29C for about half a day. That is the low for zone 5, but we have not seen temperatures that low for many years. Because of the extended cold weather, many shrubs and trees with woody parts above the snow were badly damaged by the cold. Perennials had a nice warm cover and for the most part survived the winter well.

Based on the weather, it is difficult to evaluate the survival of Super Blue. It was very cold, but the snow cover kept things in the ground warmer than normal. Would the outcome be different in a normal year with little snow cover??

Identifier Comment
SB1 Growing well
SB2 Growing well
SB3 Growing well
SB4 Growing well
SB5 dead
SB6 Growing well
SB7 Growing well
SB8 Growing well
SB9 Growing well
SB10 Growing well
SB11 dead
SB12 Growing well

Plants emerged late, and we have had a very cold spring. Leaves at this point are 1-3 inches long. SB10 and SB11 were on a steep slope, and very exposed to wind. It may account for the one death. SB5 was in a pot above ground. Surviving these conditions usually requires a zone 4 plant but with good snow cover this year, I half expected SB5 to survive. It didn’t.

Deer are not very active in the garden by mid May and since the Liriope started to grow late they probably missed the deer. No deer damage was noticed.

The foliage that was not removed in fall did not stay green. By spring it was brown and for the most part degraded. The plant does not stay evergreen in zone 5. I don’t think cutting back the foliage in fall made any difference.

Results on October 1, 2014

All of the plants that made it through the winter are still growing well, except for SB3, SB4, SB10 and SB11 which have been attacked repeatedly by rabbits. These eaten plants are still green and growing. The plants in part shade seem to be doing the best. SB8 and SB9, which are in very deep shade, are as large as the ones in full sun. The plant can obviously grow in a wide range of light conditions.

None of the plants bloomed this year.

Liriope Super Blue SB1 and SB2

Liriope ‘Super Blue’ SB1 and SB2 at Aspen Grove Gardens

 

Liriope Super Blue SB6 and SB7

Liriope ‘Super Blue’ SB6 and SB7 at Aspen Grove Gardens

 

Liriope Super Blue SB8 and SB9

Liriope ‘Super Blue’ SB8 and SB9 at Aspen Grove Gardens

 

This blog page will be updated over time to report on new findings.

References:

1) Liriope ‘Super Blue’ flowering: krolestworoslin

Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

5 Responses to 'Hardiness of Liriope ‘Super Blue’'

  1. Chica says:

    Very helpful and interesting. A number of Big Blue Liriope made it through 2 of our zone 5A Maine winters. They, however, disappeared after last winter, with a December with no snow cover that included a couple of subzero (Fahrenheit) nights, although the winter in general was a mild, zone 6-ish one. I was reading this trying to decide whether to replant, with fall mulching. Thanks.

  2. Crystal Day says:

    I’m curious to know if they are still growing well and if they ever bloomed in the following years.

  3. Ken Tidwell says:

    Your experiments with Super Blue fascinated me. I live in central Florida, zone 9a, so most of your weather fluctuations experienced by your Liriope would not pertain to mine. But this past winter we had freezing weather on a couple of mornings when it got down to 30ºF and of course it didn’t affect any of the couple of hundred clumps I have planted in my yard. Thanks for your web site and super effort.
    Ken Tidwell, Summerfield, FL

Please let me know what you think - Leave a Reply