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Garden writers Bob Lilly, Susan Carter, and Carrie Becker share their extensive knowledge of plants and gardens with timely articles and answers to your questions.  Submit your gardening questions to !

DESPERATE FOR HELP

I live in Hunters, WA, overlooking Lake Roosevelt.  My garden and front rockery get full sun year round, unfortunately accompanied by winds gusting up to 50mph.  The past few winters, our temperature has only dropped to near zero in the winter, but is known to drop as low as -20 degrees.  On the plus, we are surrounded by over a thousand acres of cow pasture- excellent manure!  I have attached a photo of my garden area.  

This has been my first gardening attempt and I dream of eventually transforming the area into a traditional English (flower) and French (veggie) garden. Very successful with the veggies, and the herb garden in front of the gardening cottage is robust, but would love advice on extremely hardy and lush for the flower area.  Some evergreen height that I could circle in flowers would be wonderful.  Many thanks, Brittany

Hi Brittany ~

We looked at your ultimate goal of having larger gardens, and eventually transforming it into an English Garden.  The first, and maybe most important challenge would be to have a good strong windbreak and protection against deer and elk.  You may not have had any visitors from the woods and pastures yet, but as soon as they find that you’re providing some of their favorite snacks they’ll be your constant companions.

We’re not certain what direction your property is facing, but let’s assume that the house and outbuildings are facing north and south, and that the wind is primarily coming in from the northwest.  The site plan we’ve given you can be changed depending on these factors.  The suggestions are based on a site plan that includes your house, other buildings and the proposed gardens.

A pine windbreak, or other appropriate evergreen trees, to surround the northwest side of your property and would also provide structure.  Washington State University Cooperative Extension has a good website that you might check out.  http://www.treesforyou.org/Selection/Articles/windbreaks.htm

A deciduous border inside the windbreak will provide further protection plus seasonal interest.  Plants might include wild roses, lilacs, Cornus stolonifera (red-trigged dogwood), Symphoricarpos albus (snowberry), and Philadelphus coronarius (mock orange).  The perennial border would go in front of this.  Here you could include asters, helianthus, helenium, phlox, peonies, and grasses.  Experimenting with perennials has always been our focus, both professionally and personally, so have fun with this.

Double Click to Enlarge

You might want to research the practice of crop rotation for your vegetables.  This is the practice of growing different crops in different places each year to control disease and replenish soil nutrients.  Seattle Tilth has some good information on this. seattletilth.org/learn/resources-1/…/croprotation-for-plant-health.

Hope these ideas help.  Please let us know if you have any further questions.

Happy gardening!

Susan, Bob, and Carrie


GREAT EVERGREEN GROUNDCOVER – Blechnum penna-marina

This small-scale hardy fern is very adaptable in the Pacific Northwest and makes a great year-round groundcover.  Blechnum penna-marina, is happy in light shade but will grow in deeper shade as well as full sun if the soil is kept moist.

Blechnum penna-marina

The new foliage emerges bronzy-red, aging to deep green.  The tightly packed fronds slowly spread by creeping rhizomes to form a very effective groundcover.  Its variety B. ‘Cristatum’ is similar and its tips are curiously crested.  In both forms the fertile fronds are reddish brown, thin and upright.

FAMILY NAME:  Blechnaceae

COMMON NAME:  Hardfern, alpine water fern

ORIGIN:  New Zealand, South America

PREFERRED GROWING CONDITIONS:  Moist, shady woodland spot in well-drained, acidic, humus-rich soil. Shade to part shade is perfect but will take full sun in the Pacific NW if kept moist.

MANAGEMENT:  Groom in late winter or early spring.  Remove old fronds as necessary.  Cut well established plants to ground in late winter to fully appreciate the new foliage; recommended only on older clumps that have become ratty or are badly damaged by winter wet or snow cover.

PROPAGATION:  Division in spring; sow spores in late summer

PESTS & DISEASES:  None

COMPANIONS & USES:  Heuchera, ajuga, dwarf polygonatum.  Amongst rocks, in rockeries, niches, and walls.

IDEAL SPACING AT PLANTING TIME FOR FULL COVERAGE IN 2-3 YEARS:  8” on center or less.  It can be a bit slow to spread in the beginning.

FOOT TRAFFIC:  no

B. penna-marina, Little Hard Fern, is an evergreen fern with a Royal Horticulture Society Award of Merit. It’s height and spread in one year are 4” x 5” and in five years will reach 4-6” x 24”+. The foliage is dark green, small, leathery and glossy.  Zone 5-8.

B. penna-marina ‘Cristatum’ is a bit smaller than the species.

FALL AND WINTER DIVISIONS

Dividing perennials is an easy way to obtain plants for your garden or to share with friends.  Some plants become overcrowded and may die out in the center, become sparse, or stop blooming and then it’s time to divide them.  While we generally think of dividing plants in the early fall or spring, many plants can be divided in late fall or winter.

If you have to dig up parts of your garden at this time of the year, there are certain perennials that can be divided at anytime. You can even leave hosta and daylily plants that have been dug up on the lawn to freeze and it won’t hurt them.

Asters and mums can be dug and divided now, as long as you replant them immediately.  Lighter-weight divisions like these should be left to spring if you have a problem with frost-heaving areas east of the Cascades and north of Mt. Vernon away from Puget Sound.

Appetizer for Rabbits

Hosta, hemerocallis, astrantia, astilbe, darmera and helianthus can all be dug up, halved or quartered, with a sharp shovel (or axe) and replanted.  It’s best to remove any damaged or broken bits.  If the crowns come apart easily or smaller pieces come loose, pot them to give away.  Protect these pots from a hard freeze, placing them close to the house, in a cold frame, or covered with evergreen branches under trees.

While you’re dividing your hosta plants, make certain to protect the newly emerging tender pips not only from slugs but from local bunnies.

November and early December is the best time to dig and divide peonies and true lilies.  The lilies are dormant in November and will move best then. Peony divisions are usually taken down to 2-3 or 3-5 eyepieces.  They will reliably bloom the following spring; spring divisions less so.

Other perennials that can be divided now include brunnera, eupatorium, lamium, and omphalodes. trollius, and vancouveria.

So, go forth and divide!

Bob Lilly

 

 

OH, IT’S DREARY OUTSIDE!

Tips for Managing the Winter Garden

As Rosemary Verey said, “A garden in winter is the absolute test of the true gardener”.  I’m sitting here watching the rain come down and feeling very guilty that I’m not outside in my rain gear.  So, I guess I’ll think about what needs to be done and make my “to-do” list.

Waiting for my Sarcococco to come into full bloom

Many of the winter jobs would prefer fair weather as opposed to mucking around in the mud and compacting the soil.  There are a few jobs, however, like cleaning and sharpening your tools, that don’t mind the weather.  Winter weeds are a continual problem in the Pacific Northwest, especially shotweed (Cardamine oligosperma), so keep control of these throughout the year.  These are easiest to pull after the frost heaves the soil a bit.

Some of the grasses are still looking good and won’t be pruned back until later when the weather gets to them and they start making a mess. Pruning some vines now, such as the grapes, is a good idea while you can see where they’ve grown to, or where you don’t want them to go.

Now, is a good time to clean up leaves and litter around the evergreen crowns of many plants, especially aster, chrysanthemum, solidago, melissa, monardo, Cardamine pratensis, Digitalis ferruginea, Lobelia x speciosa, Lobelia cardinalis, Primula ‘Wanda’, and Pulmonaria angustifolia.  Evergreen groundcovers, such as galax, saxifraga, ajuga, bolax, lamium, thyme,Mentha requienii, and Oxalis mabellanica, should also be kept clean of litter and leaves .

Mulching is one of the most important jobs we do in the garden.  Winter is the ideal time for this project after the deciduous plants have died back and the gardens have been cleaned of leaves and debris.

Before we know it, spring will be here and time to start planting again.

Sex Change

Weigela middendorffiana flower color change

Did that get your attention?  It certainly does for the bees that pollinate Weigela middendorffiana.  They have learned to visit yellow flowers preferentially, as they contain the most nectar.  As the flowers age, they turn red, and one study noticed that bees visit the older, less nutritious flowers less frequently.  Floral color change after fertilization is not uncommon (Asters, Orchids, Fuchsias), but the color change is probably dependent on age, not bee-behavior, because the pollen tubes require several days to reach the ovaries.  If the flower dropped off right after pollination, the plant wouldn’t be able to reproduce!  Thanks again go to Dan Hinkley and the Miller Garden for introducing me to this unusual shrub.

Spiny Holly?

I live in Gig Harbor, WA (cold zone 7) and would like to plant a “spiny” leaved holly that can grow to at least 10′ in height & width as a yard parameter hedge. The soil is acidic and has full shade from the towering Douglas Firs on the property. I found the below info about Blue Holly. Can you let me know if this will work before I invest the time and monies please. Any specific species recommendations that do well in the wet Pacific Northwest?

Photo Credit Jim Ross One Tree Landscape

Ilex x meserveae ‘Blue Princess’ actually prefers full sun to partly sunny conditions.  Although it may reach a height of ten-feet, it does so at a slow pace and probably wouldn’t fit your needs.  We’d recommend the standard English holly, Ilex aquifolium, as a plant that could work for you.  It does well in shade, grows fast, and can be pruned into a hedge shape if you desire.

English holly has both male and female plants and bee pollinated, so you’ll want one male holly for each hedge.  As with any new plants holly would require appropriate watering for the first several years to get it well established.

Susan, Bob, and Carrie

Rooftop trumpet vines?

Dear Expert (Carrie, Bob or Susan)
We have a client who’s property is situated on the 16th floor with a rooftop garden in downtown Seattle. The terraced garden faces south and southeast. The 4 trumpet vines are each in their own containers that are 24″ square x 26″ deep along with Algerian Ivy, trailing Rosemary. They get full sun and some wind, but are up against a wall. The foliage growth appears normal and they’re working their way up the metal trellis support. They have not bloomed yet, nor do they seem to be developing any buds. They bloomed last year (their 1st year in that spot) just coming out of a #5 nursery pot. So I can’t imagine that it’s because they’re growing in containers now. The pruning I did this spring was very light so I can’t see how that may be to blame. I also fertilized them in spring with an organic 9-3-4 all purpose fertilizer. I can’t figure out why they haven’t bloomed and hope you can.
Cheryl

Dear Cheryl,

Thank you for your question on trumpet vines, (Capsis radicans).  An American native, this vine really likes warm weather and with the exception of several days we really didn’t even have summer this year.  Also, some say it takes several years for the trumpet vine to flower but since it flowered last year this is probably not the problem.

This size of your container sounds fine, and your pruning technique was probably okay. The trumpet vine blooms on new wood, but it’s best not to cut it back too severely in the winter.

We’d recommend fertilizing your container plants more often, at least every two weeks if not weekly.  Miracle Grow would be an easy product to use.

Let us know how this works (next year).

Susan, Bob, and Carrie

Beesia?

I would like to plant some beesia at the top of a shady ravine.  I am concerned about the moisture level, though.  The area is dry shade, although I could run a line from my drip system along there.  Even though  I’ve read that beesia prefers moist soil, can it do OK with drier conditions? In this area I am trying to replace very established ivy.  If the beesia won’t work, what would you suggest?  Thanks so much!

Epimedium x versicolor 'Neosulphureum'

Epimedium x versicolor ‘Neosulphureum’

We love beesia!  Unfortunately, it wouldn’t be happy with the site you’ve described.  Beesia is an excellent ground cover for shady to part-shady, and consistently moist conditions.  I’m also curious if you’re able to remove all of the ivy.  I would put this at the top of the list, as ivy will pop back up if you haven’t gotten rid of every bit of it, and overwhelm almost any ground cover.

    Here are some suggestions of plants that would be appropriate for a dry shady site:

  • Privot honeysuckle, Lonicera pileata, is an evergreen boxwood-like foliage with a slow spreading habit, and makes a good bank-covering ground cover in part shade.
  • The woodrush, Luzula sylvayica is used as an ornamental ground cover for shady areas. It is best when planted in drifts.
  • Euphorbia amygdaloides var. robbiae also does well in dry shade, after it’s established.
  • It sounds like a site that would be appropriate for native plants such as Oregon grape, Mahonia repens, combined with sword ferns, Polystichum munitum.
  • The sedge, Carex ‘Ice Dance’ makes a nice ground cover in the shade garden, although will look it’s best if kept from average to moist conditions.
  • Evergreen epimediums are great woodland plants and are perfect for dry, shady spots. Epimedium ‘Enchantress’, E. x versicolor ‘Neosulphureum’ and ‘Sulphureum’ are among a few of the evergreen ones.

What is this?

The plant you’re inquiring about is Cardamine trifolia, commonly know as lady’s smock or 3-leaved cuckooflower. This is an attractive, well-behaved evergreen ground cover, about six-inches tall and covering up to twenty-four inches across. The dark green leaves with a purple reverse are three-parted. The white flowers are borne in early spring. Flowering is brief and they rarely set seed.

Cardamine trifolia prefers shade to part shade, but will tolerate sun if kept moist, and likes humus-rich soil. It’s a good companion plant for many plants in the spring and shade garden and especially looks good under Lace Leaf Japanese maples as there are few plants that like these conditions.
Photo: Thistledown Farm

I’m planting a privacy hedge of Leyland Cypress – What do I need to know about it?

Cupressocyparis leylandii, or Leyland cypress, is a very popular and fast-growing plant. It gives instant privacy, but this point is both a positive and negative fact. They simply grow too big.

Pruning is essential in keeping the Leyland cypress in check, and this presents other problems. If not pruned correctly, you may end up with a thicket of dead branches, or the base of the plant will become bare. Unlike yew and laurel, Leyland cypress cannot be cut back into bare wood.

I don’t think anyone knows just how tall this cypress will grow (up to 120 feet probably), but if planted as a hedge, you will have to be very diligent with your pruning or they will get out of hand very quickly. From our experience, we would trim back stray branches at the start of the growing season in April. Then in mid-summer (around July), trim the sides again to encourage denser growth, leaving the leading shoot uncut until it’s reaches the desired height. After that, the top and sides will need to be trimmed up to three times a year and tapered from the top to the bottom. This program of diligent clipping is critical and unfortunately they cannot be kept to a particularly width and will get wider and wider over time.

Spacing recommendations vary from four to eight feet, depending on how much money you want to spend. Carrie suggests five-miles apart. It sounds like you’ve already planned on spacing them every five feet and this would be fine.

Some other points you may want to consider before planting Leyland cypress is it’s susceptibility to disease, and may not be long-lived because of this (maybe only 15-years). It’s also not very drought tolerant and wants good draining soil. Ask yourself if this hedge will block out your sun to areas of the yard that are used to having sun.

As you can tell from our comments, this plant would probably not be our choice as it requires long-term and regular maintenance. Carrie suggests using plants such yew, holly, or osmanthus as a mixed and informal hedge. Susan prefers a little more formality and would opt to prune these plants, although they wouldn’t require the same amount of effort as the Leyland cypress. Bob says he would use them as a short-term solution while more preferable plants are planted in front of the cypress and allowed to grow up at a slower rate, and then remove the cypress. It would worth the time and expense to invest in Irish yews.

What’s the deal with hellebores? Should the leaves be removed from all hellebores?

hellebore

Remove the leaves of H. orientalis to the ground in January and February, being careful not to damage the stems of the emerging flowers. This is done to prevent disease from spreading and so you can see the flowers better. We usually leave the plant alone for the first two years.

H. niger is a true evergreen, so only remove the leaves that look bad.

H. argutifolius and H. foetidus have biennial stems that produce flowers in their second year. After they flower these stems can be cut to the ground and new shoots will have already emerged.
Note: When you cut the stems back don’t leave stubs, cut them to the ground.

Why don’t I ever see the flowers on my epimediums?

Well, we hope you’re cleaning up your herbaceous epimediums (E. alpinum, E. grandiflorum, E. youngianum, and their kin) as they die back.

Cut the stems of the evergreen and semi-evergreen ones to the ground in January. This should only be done once your clumps are established, in about three years. Why do we do this? To see the flowers of course, but also to see the new foliage which is often a wonderful color as it emerges in the spring.

Note: Epimedium flower stems are extremely brittle, so cutting back the leaves late is almost impossible (except for the truly patient person who has nothing else to do).