Every day for the past two weeks I have walked around the nursery, examining plants after each ‘record’ cold night. Finally, I think we may have bottomed out on the low temperatures, so I feel like I can determine which plants will continue to look good even after temperatures lower than freezing.The nursery is in the low portion of a very long valley, so cold air slips down and tends to settle over the gardens, providing a good test of how our plants fare with cold conditions. I am always surprised when a plant that dies completely back to the ground at the nursery is evergreen just a mile away, in my garden in town. For example, the Salvia melissodora that was happily blooming in the nursery gardens 2 weeks ago is completely dormant now, while the same plant at my home is still happily blooming. Temperatures at the nursery easily dropped to 20 degrees and remained there for many hours, while in town the temperature was at least 5 degrees warmer, and because of heat radiating from the house and streets the temperatures warmed more rapidly. So, the list I am going to include as being evergreen will certainly be incomplete, and those of you with warmer microclimates will have a larger list of herbs and perennials.
Now, I know no one has much spare time at this time of year, but just in case some of you are thinking about wandering into the gardens and pruning back the dead looking perennials and tidying up before company comes, I hope to discourage you. Sure, remove the dead basil and tomatoes and annual flowers like cosmos and zinnia, but all of those big dead looking perennials and shrubs and grasses should just be allowed to look ugly for a couple of months. Believe it or not, the dead upper portion of the plants protect the crowns, many of which are still showing some green. It is so easy to just prune everything back now and be done with it, but if we get additional freezes like last weeks in January or February, the crown could be damaged or killed. So even though the garden may look a bit unkempt, leave it alone and get back to cooking or wrapping presents, or perhaps reading up on some new plants you would like to add to the garden in case a few plants do not return in the spring. Most importantly, don’t assume everything that died to the ground is dead! Most of the perennials we sell will return next spring – even the hardest hit and deadest looking Salvia. So be sure to give plants a chance to return from dormancy before you pull them out.
Here is a list of plants that continue to look good in our gardens in the middle of December. I won’t go into many of them in detail, but this is a reference so you can come out and explore for yourself, or do some research in case you would like to add more ‘backbone’ to some empty spots in the garden.
*Lavender – all species except pinnata and multifida.
*Rosemary – they are all very sturdy and look great
*Thyme – many species and varieties look great. The culinary varieties ‘English Wedgewood’ and ‘caraway’ are beautiful, and most of the ornamental groundcover varieties are still beautiful. Varieties such as’Elfin’, ‘Doone Valley’, ‘spicy orange’, and ‘wooly’ are doing very well
*Satureja – the evergreen winter species, Satureja montana, looks and tastes great. The closely related Satureja thymbra and Thymbra spicata are two other great winter culinary herbs that are real troopers in the cold, and they continue to look great!
*Oregano – so many still look great, especially the popular ‘Italian’ variety. I am not sure what kind of cold conditions it would need to actually die back but it looks great now and I have never seen any damage on this plant. Lots of other culinary oregano look great after the hard freeze, including the groundcovers ‘Dwarf Greek’, ‘Rosenkuppel’, and ‘Betty Rollins’. One of my favorite ornamental oreganos, Origanum dictamnus, or dittany of Crete, has gray, fuzzy leaves and is looking beautiful in both the ground and containers.
The Salvia genus is huge, with both hardy evergreen perennials, herbaceous perennials and annuals. While many of them have died back to the ground, there are many that continue to look great during winter. Salvia microphylla ‘Hot Lips’ is taking a bit of a break from flowering, but is a big and robust background plant. Salvia fruticosa, or Greek Sage, is an unexpected trooper in this weather. Growing to 6 feet tall, this upright evergreen shrub is fragrant, interesting for cooking and tea making, and is covered with soft pink blossoms during the spring. All of the colors of Salvia greggii withstood the cold weather with no problem, and a few of them such as ‘Raspberry’ and ‘Dark Dancer’ are still blooming. Salvia chamaedryoides also looks great after the freeze, and so do all of the Salvia clevelandii and Salvia clevelandii hybrids such as ‘Pozo Blue’. The traditional Salvia for cooking, Salvia officinalis ‘Berggarten’ as well as the variegated varieties, all came through winter with flying colors.
Here is a list of the many other perennials that look terrific now.
Achillea tomentosa ‘King Edward’ – groundcover with a yellow flower
Achillea ageratifolia – Greek yarrow – tough groundcover with pretty white blooms
Correa ‘Carmine Bells’ – Australian fuchsia – short evergreen shrub with dusky rose tubular flowers Nov-April. I am pleasantly surprised by this one.
Cotula hispida – native to the mountains of South Africa. Beautiful feathery gray low growing foliage, yellow bloom
Cistus – the rock rose genus – these plants are lovely at this time of year, and can really be used as part of the backbone of the garden. I especially love Cistus creticus, from which the holy incense labdanum is derived. Pink blooms in the spring, and lovely wavy gray leaves on a 2 foot upright shrub.
Euphorbia – so many choices, many of which look beautiful in the garden in the winter, and bloom early in the year. Euphorbia ‘Blackbird’ and ‘Glacier Blue’ look lovely and are great container specimens.
Centranthus – can be a bit invasive, but they can cover some space.
Penstemon – many to choose from, just remember to divide them in the spring every few years
Marrubium – beautiful silvery leaves look great all winter, especially Marrubium incanum and Marrubium rotundifolium.
Heuchera – so many foliage colors to choose from, great for partial shade
Silene ‘Clifford Moor’ – another tough groundcover for partial shade that looks great all year.
Prostanthera rotundifolium – Australian mint bush – 12 ft evergreen fragrant shrub, showy purple bell shaped blooms
Lamium – dead nettles – variegated evergreen shade loving groundcover
Laurus nobilis – Grecian bay – large growing evergreen tree
Teucrium – so many species of germander, Teucrium cossonii is a sturdy groundcover, and Teucrium ackermanii is a lovely silver leaved groundcover with deep purple flowers. The big shrubby Teucrium fruticans is great for full sun.
Phlomis lanata – Jerusalem sage – 3 ft or more, a big happy fragrant evergreen with yellow blooms
Hypericum – St Johns wort – some of the shrubby specimens are lovely in the winter – ‘Albury Purple’ is a lovely 3 ft tall perennial, with violet foliage in the winter.
Sempervivum and sedum – most sempervivum are winter hardy, as are groundcover sedum.
I thought this would be a very short article, but it turns out there are quite a few plants still looking beautiful after last weeks freeze. You may not have time to add some of these to the garden right not, but these are great plants to add to your garden at any time of the year.