Threadleaf Coreopsis

Coreopsis 'Jive' and 'Salsa'

Mauve colored Veronica 'Eveline' and Penstemon 'Dark Towers', with its deep maroon stems and light pink flowers looked pretty together in my front garden for quite a number of weeks, but as the summer slipped quietly from July into August, they both were starting to look a bit weary. 

Hoping for a fresh flush of flowers in early fall, I ruthlessly pruned them back. Cutting any perennial back hard is always a case of short term pain for long term gain. Often a plant looks like hell before it bounces back.

To disguise the mess I created, I bought a big pot of annual Coreopsis 'Jive' and placed it right into the flower border.

I have always been a fan of Threadleaf Coreopsis.  I have perennial Coreopsis verticillata 'Moonbeam' in the front and back gardens.

Coreopsis verticillata 'Moonbeam' : has soft, ferny foliage and buttery-yellow flowers in late July/August.  Deadheading encourages new flowers and an extended bloom time. This is an easy care plant that tolerates a range of soil types and growing conditions. Full sun. Height: 30-45 cm, Spread: 30-45 cm. Note: Moonbeam is essentially sterile and must be propagated by division or cuttings. USDA Zones 4-9.

'Zagreb' is another popular cultivar with flowers that are a deeper, more golden-yellow.

Coreopsis verticillata 'Zagreb': has the same ferny foliage and golden-yellow flowers in late July/August. Full sun. Height: 20-30 cm, Spread: 30-45 cm. USDA Zones 4-9.

Coreopsis verticillata 'Golden Gain': offers the same golden yellow flower as 'Zagreb' on a plant that is a little taller than 'Moonbeam'. Again full sun. Height: 60-75 cm, Spread: 45-60 cm. USDA Zones 4-9.

This pink cultivar is sometimes sold as a perennial here, but it has never been hardy in my Zone 6b garden. 

Coreopsis rosea 'American Dream':  has the same threadleaf foliage as 'Moonbeam', but with pink flowers in late July/August. Full sun. Height: 30-45 cm, Spread: 45-50 cm. Coreopsis rosea 'American Dream' prefers average to moist soil. USDA Zones 4-9.

Coreopsis 'Route 66' is also a perennial that has to be treated like an annual here (hardy only to Zone 5).

Coreopsis 'Route 66': has starry yellow flowers splattered more or less with maroon. (Each flower is a little different than the next.) This species is native to the Eastern USA and tolerates heat and humidity well. It prefers dry growing conditions and is happiest in sandy, poor or rocky soil that offers good drainage. Full sun. Height: 50-60 cm, Spread: 45-60 cm. USDA Zones 5-9.

Coreopsis 'Red Satin' is final example of a perennial that must be treated like as annual here in southern Ontario (hardy only to Zone 5).

Coreopsis 'Red Satin': has maroon flowers summer to fall. It is native to the Eastern USA where it grows in hot, dry conditions. Like 'Route 66', it is quite happy in poor, sandy soil and is drought tolerant once established. Full sun. Height: 45-60 cm, Spread: 35-45 cm. USDA Zones 5-9.

In recent years, Coreopsis tinctoria and Coreopsis rosea have been hybridized to produce many new annual varieties. 

Coreopsis 'Jive' is part of the new Coloropsis series. Full sun. Height: 30-45 cm, Spread: 30-45 cm. 

Coreopsis 'Salsa': is part of the same series as 'Jive' and is compact, upright annual with yellow flowers that have a reddish-brown centre. Full sun. Height: 30-45 cm, Spread: 30-45 cm. 

One drawback is that many of these new annuals are sterile and must be grown from cuttings. Sadly there is no possibility of collecting seed each fall.

A nice companion plant for any Threadleaf Coreopsis might be Calamintha, which is also quite delicate in appearance.

Dwarf Calamint, Calamintha nepeta ssp. nepta: has arching spays of pale mauve-blue flowers. The foliage of this plant has a slight minty fragrance. Full sun or light shade. It tolerates average, dry and moist growing conditions and is suitable for normal, sandy or clay soils. Bees love it! Height: 20-30 cm, Spread 30-45 cm Hardy USDA Zones 4-9.

Here Coreopsis is combined with some purple Liatris spicata and a great mauve colored Geranium called 'Rozanne'.

Geranium 'Rozanne': Height: 30-50 cm, Spread: 45-60 cm. Full sun to part shade. Normal, sandy or clay soil are fine. Average to moist soil. Hardy USDA zones 4-9.

In my back garden 'Moonbeam', which is about to flower, is tucked into a little corner along with Sedum, Rudbeckia and Artemesia schmidtiana 'Silver Mound'.

Artemisia schmidtiana 'Silver Mound': makes a nice, compact mound of soft, silver-grey foliage. Full sun or very light shade. It doesn't mind poor soil and dry conditions. Height: 25-35 cm, Spread: 30-40 cm. Hardy UDA Zones 4-9.

One word of warning: the pot of 'Jive' Coreopsis on the pricy side. 

So far though, it has been well worth it. With Jive's profusion of cheerful white and reddish-brown flowers, a section of the front garden that was looking a bit tatty is bound to look great for weeks.

Garden Canadensis, Part 3: More Plants & Planting Combinations

In this, the third in a series of blog posts on Garden Canadensis, Chen and Linda's country garden located near Milton, Ontario, we will take a look at interesting perennials and plant pairings for sun and part shade.

(In case you missed the earlier posts here are links: Part 1 and Part 2.)

Planting Combination: Penstemon 'Dark Towers' and Geranium 'Rozanne' and Lavender, Lavandula.

Why this works: Though I am focusing in on the flowers at the moment, I want to take a second and point out the valuable role that the conifers play in this grouping. The blooms in this combination of plants are dainty and their stems are fine and wispy. They flower would tend less noticable without the wonderful and varied backdrop of green that the conifers provide.

Even though the flowers colors are all quite different in this combination of plants, they all have a purply cast that makes the grouping cohesive.

Penstemon 'Dark Towers': Height: 60-90 cm, Spread: 45-60 cm. Full sun. Normal, sandy or clay soil are fine. Average to dry conditions. Zones: USDA 3-9

Geranium 'Rozanne': Height: 30-50 cm, Spread: 45-60 cm. Full sun to part shade. Normal, sandy or clay soil are fine. Average to moist soil.

Chen says, "I have had this Geranium for years. It is a reliable and forgiving beauty."

Geranium sanguineum var. striatum

Geranium sanguineum var. striatum: Height: 15-20 cm, Spread: 45-60 cm. Full sun to part shade. Normal, sandy or clay soil are fine. It tolerates a range of soil conditions: dry to average or moist soil. Zones: USDA 3-9

 Chen Notes: " I like its pale pink flowers and nice green foliage for the front of borders. It spreads fast,  bordering on weedy."

Lavender, Lavandula

Plant Combination: Pale pink Geranium sanguineum var. striatum and Lavender, Lavandula. 

Why this works: Delicate and pretty in combination is always charming.

On the subject of Lavender, Chen writes: 

"This is one of the 'must have' perennials in my garden. I grow them for their ornamental foliage and flowers, and for their easily controlled, neat habit. Most of the Lavandula in my garden are from seeds I sowed many years ago. They self-sow a little, but not enough."

Those of you who regularly follow my blog know that I have struggled to grow Lavender successfully, so I asked Chen if he gave his plants any special treatment:

"The only thing I pay attention to for Lavandula are: not to locate them in a wet spot, give them as much light as possible and a pruning to keep a tidy shape. I do not have any special soil preparation for them. In fact, they seem to do equally well in poor soil. Some of them have even self-sown in the crevices of standing rocks."

Plant Combination: Another mix using Pale pink Geranium sanguineum var. striatum. Here it is combined with ground cover Sedum rupestre 'Angelina'.

Sedum rupestre 'Angelina': Height: 15-20 cm, Spread: 45-60 cm. Full sun. Dry to Average  conditions. Zones: USDA 3-9

Astrantia major 'Roma': Average to moist soil and part shade to sun are best for Astrantia. Height: 60-90 cm, Spread: 45-60, USDA Zones: 3-9

Plant pairing: Chen combines his Astrantia major 'Roma' with a Japanese Iris and purple Geranium 'Rozanne'. See a picture of the mix of all three plants on Chen's website.

In Chen's garden, a problem with voles means he has to struggle to keep his Astrantia flourishing. This area of the garden gets morning sun and passes into shade mid-afernoon.

Giant White Fleece Flower, Persicaria Polymorpha: Height: 90-120 cm, Spread: 80-90 cm. Full sun to part shade. Average to moist conditions. Zones: USDA 3-9

Chen writes:

"This is a lovely giant perennial. I am fortunate to have enough room in my garden to accommodate it. It is used as a bold structure plant and has attractive creamy-white plumes that bloom for a long time from late spring."

Plant Pairing: Coreopsis 'Mercury Rising' and Penstemon 'Husker's Red'. You can see Coreopsis 'Mercury Rising' in the foreground on the left. The front of a border is a perfect place for it.

Coreopsis 'Mercury Rising': Height: 30-45 cm, Spread: 30-45 cm. Full sun. Tolerates a range of conditions: dry to average and moist soil. Zones: The jury is still out on the true hardiness of this cultivar.

Plant Pairing: Coreopsis verticillata with burgundy Heuchera 

Why this works: The soft cloud of ferny Coreopsis verticillata makes a nice backdrop for the wands of tiny Heuchera flowers. 

On the subject of Coreopsis verticillata, Chen notes:

"I have had this for years. I don't particularly like the yellow flowers, but the ferny, refreshing green foliage makes it worth having around."

Coreopsis verticillata: Height: 30-45 cm, Spread: 30-45 cm. Full sun. Tolerates a range of conditons: dry to average and moist soil. Zones: USDA 4-9.

Gypsophillia cerastoides: This little pink flower caught my eye in Chen's rock garden. On his website, he warns that it self-sows to the point of being weedy. It sure is pretty though!

Lychnis coronaria: is a short lived perennial. Height: 60-90 cm, Spread: 45-50 cm. Full sun. Normal, sandy or clay soil are fine. Average to dry conditions. Zones: USDA 3-9

Chen notes,"This flower color is a little too bright to mix easily with other plants. The silvery foliage is what I want. It self-sows quite a bit, bordering on weedy."

Chen:

"The 'Dragon's Head' is an interesting group of perennials with various shades of attractive bluish flowers. It is most commonly grown by rock gardeners. Some books have warned that this is a highly invasive group of plants. It is my belief that only some of Dracocephalums behave badly."

See Chen's collection of Dracoephalum and read his full notes here.

Final Plant combination: Dianthus and Heuchera' Paris'

Chen:

"I used to think of Dianthus mostly as fillers, because they are easy to sow from seeds. Over the years I have come to like them as much as other ornamental perennials... 

Dianthus propagates from seeds and grows easily. Although they produce tons of seeds each season, so far, I find that they mostly self-sow in their own little patch and do not run around wildly like Forget-Me-Nots. 

I find the taller varieties have floppy habits. All my Dianthus look like brown patches in late summer. You can easily do a clean-up by pruning off the brown tops, but if you want some self-sown babies, you need to save some for seeds. If you are willing to address these shortcomings in your composition and maintenance schedule, Dianthus belongs in your garden."

In the final post on Chen's garden we will look at his impressive collection of conifers and see how he has combined them beautifully with other plants.

Have a wonderful weekend!