OT Hardiness Trials Part 1

 

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EXPERIENCES WITH GROWING THE NEWER LILY VARIETIES ON THE PRAIRIES (2002)

Here in Alberta, it is often a challenge to extend the lily blooming season with hardy, attractive garden varieties. The later blooming lilies, (trumpets and orientals) all seem to be less hardy than the asiatics, and until the last few years, most gardeners have been limited to growing less hardy lilies in pots or containers, or treating them as annuals. Lucky for us, there are also many hybridizers around the world with the goal of extending bloom seasons. Particularly of interest to northern gardeners are the breeding efforts of Lynn Collicut and Dr. Wilbert Ronald out of Manitoba, who have released a number of interdivisional lily hybrids, which are proving to be hardy in our Zone 3 gardens. Prices have ranged from $12.00 to $40.00 per bulb on these newer crosses, but are now decreasing as these lilies have been on the market a few years now.

Large dutch companies are now mass-producing new interdivisional crosses as well, and as a result many new varieties are becoming readily available through garden centers, greenhouses and specialty growers alike. Mass production also means lower pricing on the dutch hybrids, and many of these you will see retailed in the range of $6 to $10.00 per bulb. The unfortunate aspect of mass production and release is the lack of accurate information regarding hardiness and culture. Typically all garden centres and greenhouses source their variety tags from the same companies, who have no idea what hardiness level a plant may really be. To add to the confusion, they will use a photo of any lily similar in looks to the actual variety noted by name. I have found asiatic tags saying they were rated for Zone 4 - most people familiar with lilies know they are fully hardy to Zone 2! I have also seen misinformation go the other way...Oriental and Orienpet tags stating hardiness to Zone 3, when I know full well they are only hardy to Zone 4, and if they do survive a Zone 3 winter, it is only by chance and they certainly do not thrive or reproduce in this zone.

Please note that I am referring to plant hardiness zones in Canada, whether using the old or new zone map, I am in a Zone 3.

A word on purchasing, particularly relevant to Canadian bred lilies - our Canadian breeders are encouraged to continue their excellent breeding work through the payment of royalty fees by all growers and retailers, and I'm sure you would like to encourage them to continue producing hardy, new varieties as much as I would! In that respect, I urge you all to purchase your bulbs from reputable growers who purchase bulbs directly from the breeders, or who at the very least pay royalties for propagating the breeder's material on a regular basis. I also encourage you to purchase from your regional lily society as often bulbs they offer at sales are purchased directly from the breeders, which benefits the breeder and the society.

ORIENPETS:

The first group to familiarize yourself with, are interdivisional crosses consisting of aurelian trumpets and the tender orientals, and are commonly referred to as 'orienpets'. These crosses bloom 3-5 weeks later than asiatics, are very fragrant, grow 3 to 5 feet tall, and have exotic flower forms and colors to tempt us. Although most breeders state these lilies are hardy to Zone 3, I believe they are reliably hardy to Zone 4, as they have given us mixed results in our Zone 3 gardens over the past 4 years.

I find those bred on the prairies definitely grow best on the prairies, such as Wilbert Ronald & Lynn Collicut's selections (Northern Star, Northern Beauty, Northern Carillon, Northern Sensation, Starburst Sensation, Easter Morn, Easter Dawn). Scheherazade and Leslie Woodriff (both orienpets bred outside of Canada) have proven reliably hardy here at my location as well. The jury is out until this spring (2003) on Catherine The Great, Arabesque, Anastasia, and Silk Screen as I have lost some of these repeatedly, and others were just planted in Spring 2002. It is worth noting that previous trials of these varieties I've lost in past, were done without the benefit of any mulch before winter. This year's trial involved heavy mulching for all! I am excited to have a few of Dick Bazett's orienpets to trial in our zone 3 gardens this year as well. Mr. Bazett gardens and hybridizes lilies in British Columbia, and has a host of new, breathtaking orienpets with exciting new colors to be released in the future, as well as a few such as Regal Star, which have been available for a few years now.

I find that providing they are planted at a minimum depth of 8 inches, planted in spring so as to allow good root growth over summer, and mulched heavily, these lilies will survive our winters without snow - which is the true test of hardiness. Most orienpets are doing very well in provinces such as Manitoba where they still get good snow cover over winter, but here in AB mixed results are found when we have no snow cover. Again, I recommend planting these in spring only, to a depth of 8-12 inches, in full sun, with heavy mulching in fall before snow falls. The mulch must be removed as soon as possible in spring, in order for the bulb to warm up and start growing in a timely manner (because they are planted deeper, they will take longer to emerge). The alternative is to grow them in pots and overwinter in a protected spot or root cellar.

My biggest concern with the hardiness of the orienpets revolves around their late blooming natures - one of the reasons we want to grow them in the first place! We experience killing frosts as early as mid August, which is often the time the buds are just maturing on these varieties here at our location. If they freeze hard, too early in their life cycle, the bulb is unable to gather enough energy before winter sets in, and this may very well be the reason they do not survive the winter extremes in some locations on the prairies. I believe they have the ability to still collect some energy through the stems even after they are limp from a killing frost, so I leave those ugly, frozen stems on them despite their unsightly appearance.

AURELIAN - ASIATIC CROSSES:

Yet another breakthrough in lily breeding is the Aurelian-Asiatic crosses (AA); crosses between hardy asiatics and aurelian trumpets, resulting in hardy bulbs with magnificent, huge, fragrant blooms which show themselves in August through September. These varieties tend to grow around 3 feet tall on average. Plant them at least 6 inches deep, mulch in zones 1 and 2 is recommended, and be sure these are in full sun. Finally, a fragrant AND hardy lily for the prairies!

The Canadian Belles Series, also from the team of Lynn Collicut and Wilbert Ronald, have proven themselves hardy in many Zone 3 gardens, without extra protection. They also feature good resistance to botrytis and fusarium. The series consists of Blushing Belles, Creamy Belles, Fiery Belles, Golden Belles, Ivory Belles, Purple Belles and Silky Belles, to date. Currently I have growing Creamy, Fiery, Ivory, Blushing and Silky Belles but have yet to test for winter hardiness without the benefit of mulch - this spring (2003) I'll know if they can survive without mulch, as I established a test bed for this purpose in Fall 2002.

There are many other factors which can influence the hardiness of lily bulbs in general, including the planting conditions, growing conditions throughout the season, and the biggest stress, our unpredictable weather. What have I done to help them overcome the stresses of weather? Mulch, mulch and more mulch! Mulch is effective in controlling ground temperature, moisture levels, pests and soil born diseases. Mulch spread throughout the beds, to a depth of even 2 inches is very beneficial in keeping moisture in the ground - I cannot stress this enough, certainly not in these years of drought we are all experiencing! I would recommend mulch to a depth of at least 4 inches wherever possible, but any depth is better than none at all. Mulch also provides extra winter protection during years without snow cover. I highly recommend applying mulch over varieties that are under particular stress, and/or are less hardy (such as the orienpets, trumpets and orientals) to a depth of 6-8 inches for winter. Mulch is also effective in keeping the ground temperature consistent in spring, and slowing the thawing process so that the lilies will emerge a little later than those without mulch, and perhaps escape the late spring frosts as a result. Slow and steady ground temperatures encourage good root systems to develop before top growth begins. We use bark mulch throughout our lily beds, and have used dried grass clippings and sawdust in the past as well. If using a form of wood mulch, extra nitrogen fertilizer may be needed during the growing season, as wood mulches tend to deplete the nitrogen content in the soil quicker.

In closing, I wish to invite those of you who have also grown some of the newer interdivisional crosses to share your experiences so we may all benefit from the growing experiences of our fellow friends and gardeners. Collectively, we can come up with a strategy that works in extending the bloom season of that highly addictive flower, the lily!

This article was originally written for the Edmonton Hort Society and Alberta Regional Lily Society newsletters, Winter 2002. For an update on our hardiness trials from 2003 and 2004, please use the links below.  I am long overdue to update on this topic again - for one thing, we no longer find it necessary to plant the OT's as deep as mentioned here, although they still get a good layer of mulch.


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