Northern Shade Gardening

The perennials in my garden with semi-evergreen leaves are still looking good, despite the below freezing temperatures,  but the – 35°  C (-31 ° F) temperatures that will come later this winter will test their cold hardiness. Alternating cold and warming spells  can stress perennials, with the freeze thaw cycle.  We usually get consistent snow cover from December to April, which helps to insulate the plants. I’ve found that adding a layer of deciduous leaves over them also helps insulate the perennials from a cold zone 3 winter.

Just before the snow comes, the leaves from the trees overhead cover the garden. The trees do a pretty good job, and I assist by helping to fill in the garden sections that are missed, covering the perennials up with the fallen leaves. All of the perennial crowns benefit from the winter leaf mulch, and the plants still holding onto their leaves will appreciate the above ground protection too.

Helleborus Ivory Prince leaves before covering

Here is the fantastic foliage of Helleborus ‘Ivory Prince’. These are semi-evergreen, and will stay on the plants until spring, but that means that the severe temperatures, and drying winds can damage these leaves. Last year, the leaf cover kept the Helleborus in excellent shape until April, as well as protecting the crowns.

Helleborus Ivory Prince under fall leaves

A thick leaf pile collects under the willow tree, and here it is on top of the Helleborus. I threw some  extra armfuls over them. The slender willow branches placed over top help keep the leaves in place when the wind blows.

Heuchera 'Mint Frost' in fall leaves

Heuchera (coral bells) can heave out of the ground over winter, but the extra leaf layer helps to insulate them. I had no heaving of these perennials last winter.

Heuchera 'Plum Pudding' under fall leaves

The Heuchera ‘Plum Pudding’ (coral bells) contrast with the deciduous leaves. You can see the wonderful burgundy coloured stem on these perennials, while the purple and silver colour of the leaves is even stronger from the cold temperatures.

Campanula under fall leaves

In the above photo, the Campanula (bellflowers) are partially covered with leaves. Most of the bellflowers I grow are very hardy in zone 3, and survive fine without leaf cover, but the extra layer in the garden won’t hurt them.

When the snow melts in spring, and the temperatures get warm, I remove the protective leaf cover from the garden beds. This is the fun part of spring gardening, pulling back the leaf mulch to see what is growing underneath. Some of the leaves have broken into small pieces, and will decompose into the garden soil, forming part of the mulch. The rest is set aside to decompose and be added back later. The perennials will use the good nutrients in the leaves.

Although we’ve had  a few nice weeks, the temperatures are consistently below freezing at night. The willow tree, which hangs on the longest, is losing the last of  its leaves. While the intricate pattern of branches is outlined overhead, underneath the fallen leaves will blanket the garden, and help protect the perennials.

Galanthus Puschkinia Scilla bulbs

I’ve been adding more of the smaller spring bulbs to my garden this fall. These are easy to tuck into a garden bed, in between perennials. When the bulbs die back by summer, the perennials will take their place, extending the flowering time. I’ve expanded some established groups of bulbs, adding more for a splashier spring show. In the photo above, you can see the Galanthus (snowdrops), Puschkinia (striped squills) and Scilla (squills) bulbs from left to right.

I did most of my bulb planting in September, before my zone gets much frost. This gives the bulbs a chance to settle in before the cold temperatures stop the growth. During the past few weeks, the temperatures went above freezing, and I saw some bulbs on sale. I planted some more of my favourites in the garden. It’s a little late in the season to be adding bulbs in zone 3, but the ones I added late last year survived, so I’m optimistic again this year.

Scilla siberica squill flowers May

Many of the little bulbs have smaller foliage that fades away quickly, like these Scilla. After the blooms have gone, the bulb leaves need to photosynthesize, but larger leaves can look messy as they decay. The short, narrower leaves of the littlest bulbs are more easily hidden by surrounding perennials, and also die back quickly. They can store up energy for next year, without looking too unkempt.

small bulb packages

The smaller bulbs look especially charming in spring, when very few plants are blooming. Before the attention grabbing perennials start to flower, you can appreciate the elfin charm of the dainty blooms. The Puschkina scilloides are less than 15 cm (6 in) tall, and at any other time of the year they would be hidden in the garden, but they stand out when there is very little foliage around. They look eye-catching when planted in large groups, but can be appreciated in a small group, if they are planted next to the steps, or in a corner near a path.

Galanthus elwesii snowdrop bulbs

I added some more of the earliest bulb of all, Galanthus elwesii (snowdrops), with the charming white petals. The tiny snowdrop bulbs can be planted fairly close together, and these definitely need a large group, or tight planting to show up well. These are planted at the edge of a larger group of Galanthus.

Galanthus elwesii flower closeup May

Here is a snowdrop flower from last May. As the first blooms in the spring garden, the Galanthus get lots of attention. Those bright outer petals, hide the little green markings, unless you get down for a closeup look. In earliest spring, you can appreciate the subtle details.

Puschkinia libanotica striped squill flower May

The Puschkinia scilloides var libanotica (striped squills) bloom after the Galanthus in my garden. These Puschkinia  are some of the showiest of the petite bulbs. They have large clusters of small blue and white petals. I have some Puschkinia scilloides ‘Alba’ that bloom in all white too. They are nice, but I prefer the lively little blue racing stripes of these bulbs.

Puschkinia libanotica striped squill bulbs

The Puschkinia bulbs can be planted close, a few cm apart, so the flowers almost touch each other, and display well. In the photo above, I’m adding these between Brunnera plants, next to an established patch of striped squills. The group looked great last spring, but I thought it could be larger. I dig a shallow hole, and put about 20 of  the bulbs in it, with their points up. Then dig another hole between the next perennials. They get covered up with soil, watered in, and next a layer of fall leaves over top.

Scilla siberica squill bulbs

The blue Scilla siberica (squills) bloom soon after the striped squills. These look fantastic paired with other white or blue flowers. Even the bulbs themselves have a purplish blue covering when you plant them. The actual flowers have have a true blue colour, as shown in the picture second from the top.

Puschkinia libanotica and snow May

Here is a typical spring picture from a northern garden, little Puschkinia snow cones, from last May. The tiny flowers of the small bulbs usually recover quickly from a spring snow, and continue to look good when the sun shines again. This is probably one of the best reasons for planting these hardy bulbs.

Earlier this fall I wrote about planting some crocus bulbs, pairing the small Muscari (grape hyacinth) bulbs with tulips, and underplanting shrubs with Chionodoxa (glory of the snow) bulbs. When there is very little new green foliage in early spring, it is fun to wander around the garden, looking for the latest bulbs to bloom. I’ll be ready for spring to burst with colour, after the monotones of winter.

Hydrangea and birdbath fall leaves

Hydrangea shrubs have enough room underneath, that you can make a beautiful layered garden by underplanting them with shorter plants. In summer I have some dwarf Campanula (bellflowers) producing purplish blue star shaped flowers in a low carpet under this Hydrangea paniculata. I love the look, and wanted to extend it to spring, so I’ve planted some Chionodoxa forbesii (glory of the snow) bulbs underneath. These early spring bulbs should flower before the bellflowers bloom, with their own version of starry flowers.

Campanula porscharskyana (bellflower) in flower

Above is  a photo of  Campanula porscharskyana (Serbian bellflower) from this summer. They start flowering midway through June, and continue intermittently all summer, and into fall. They look especially pretty under the Hydrangea, even before it flowers,  twinkling up through the branches. They are a gorgeous shade of purplish blue, with five narrow petals and white towards the centre. These bellflowers grows quite low to the ground, so they don’t interfere with the Hydrangea branches, and they fill the bare area underneath with beauty. Then in August and September, when the Hydrangea blooms in white, the little blue flowers of the Campanula look lovely paired with the large panicles. However, there are no flowers underneath the shrub before mid June, just the bellflower foliage.

Chionodoxa luciliae (glory of the snow) flowers spring

I  added some glory of the snow bulbs to bring some early blooms to this area. The blue stars are reminiscent of the Campanula and should have a similar effect. These have six petals, a dark line down each petal, and a white centre. The Chionodoxa luciliae start flowering during May in my zone 3 garden, so the Chionodoxa forbesii should start the colour show early too, before the bellflowers. These two Chionodoxa species seem interchangeable now. The pretty blue bulbs will bring some spring cheer, while the Hydrangea stems are still leafless. Then when the glory of the snow flowers fade, the bellflower groundcover should easily hide the slender bulb foliage as it dies back for the season. Usually the  Chionodoxa foliage disappears quickly.

planting Chionodoxa forbesii (glory of the snow)bulbs

Here is one of the bulb planting holes, in between the Campanula poscharskyana plants. I dug narrow holes among the perennials, to minimize the root damage. Then I planted 5 to 10 bulbs in each hole. Altogether I planted 50 Chionodoxa forbesii, but I could have planted more. These bulbs cover the  ground under the front half of the Hydrangea, and a bit around the sides. I could plant another 50 to really carpet the ground under the PG Hydrangea.

fall leaves under Hydrangea

The fall leaves were already covering the garden bed, as I watered in the newly planted bulbs. This will be some of my last outdoor gardening fun for the year, since the temperatures are so cool now. It is probably a little late to be planting bulbs in zone 3, but the weather warmed above freezing this week, the bulbs were on sale, and the picture of more blue flowers was running through my mind. Soon, a white quilt will be spread over top of the brown and green patchwork one. However, come spring, the flower parade will start as soon as the snow melts, and the early spring bulbs bloom.