Patio planters

Whether your garden is small or sprawling, add a dash of colour and creativity with some container plantings.

Credit: John Glover & iStock / Scrambled

Whether your garden is small or sprawling, add a dash of colour and creativity with some container plantings

If you have a garden with plenty of space, you may think container gardening isn’t for you, but there are lots of reasons for everyone to plant their treasures into pots.

For a garden that is mostly low-maintenance shrubs, containers are a great way to have colourful and interesting plants close to the house. Where deer are a problem, patio pots on a deck may be the only way to enjoy favourite showpieces without having them constantly nibbled. And if you are one of those gardeners who constantly moves plants around (sometimes with disastrous results, especially when they are dug up and moved at the wrong time of year), container gardening is a perfect solution: you can rearrange the pots as often as you like without disturbing the plant roots.

I have gardened this way for years and one plant I have great success with is Agapanthus (African lily). It seems the more rootbound these plants are the better they bloom, as long as they get plenty of sun and regular watering throughout the heat of high summer. In the late 1940s, the famous Headbourne Hybrids Agapanthus were raised in England from seed sent from Kirstenbosch Botanic Garden in South Africa. Out of this group have been selected many named cultivars, including ‘Bressingham Blue’. It is an exceptional deep blue with somewhat tubular flowers, and being more compact, it is excellent for a patio pot. Agapanthus campanulatus ssp.patens, native to the Drakensberg Mountains of South Africa, is probably the hardiest of the whole group. It has strap-like, bright-green foliage and more open, sky-blue flowers in flowerheads resembling those of giant alliums.

They are hardy to minus 15º C (5º F), but just to be on the safe side I pop mine in a prefabricated Plexiglas cold frame on my more sheltered north-facing balcony for the winter months. However, I must share a story about our former director at the UBC Botanical Garden, Dr. Roy Taylor, who had a couple of pots of the really tender agapanthus next to his swimming pool. He overwintered them in the trunk of his car and drove them back and forth between Richmond and UBC five days a week. Having grown up on the Prairies, he felt one needed weight in the trunk to get by on snowy and icy roads, so those pots did double duty!

Simple arrangements of plants predominantly grown for their foliage can also be pleasing. All of the following show up well in their terra-cotta pots:

YUCCA:

A handsome variegated yucca, Yucca gloriosa ‘Variegata’, which is native from northern Carolina to Florida and hardy to zone 7 and up. It may flower happily in that pot in a year or two or it may get too large and need to be transplanted into the garden. Yuccas in pots are excellent for hot sunny patios and are very forgiving if left unwatered for a few days; they require minimal fertilizing – just one liquid feeding in spring to brighten up the new foliage.

BAY LAUREL:

The attractive shrub Laurus nobilis is the true bay laurel, whose aromatic leaves are invaluable in the kitchen for flavouring soups and stews. And, trust me, the flavour of freshly picked bay leaves is much nicer than those dried ones you buy in the store.

Our recent mild winters allow this borderline-hardy Mediterranean native to survive, although there is always a possibility that terra-cotta pots, unless they are the frost-proof type, will break from freezing and thawing. Just to be on the safe side, I would put it (along with agapanthus) in an unheated garage, near a window, from late November to late February. One other point about bay laurel: it has the potential to become quite a tall tree. A friend in Vancouver has one in a sheltered location and it is over 4 m (13 ft.) tall and very happy. It will eventually need to be moved into a garden and, sadly, may not make it out of the pot with all of its roots intact unless the pot is broken.

SPIKEMOSS

Selaginella is a genus of plants called spikemoss that have great foliage. A dwarf spruce and mugo pine promise hardiness and evergreen foliage and a large fern softens the combination. The twisted, sword-like, silvery-grey leaves belong to Astelia chathamica, a most attractive plant native to the Chatham Islands of New Zealand. We have a beautiful pair of these plants in pots out at UBC that have to be overwintered in a cool greenhouse. In zone-8 areas, like Victoria, it can stay outside all winter. Despite its silvery foliage, it enjoys moist soil and grows in sun or part shade, although through these past couple of hot summers they have suffered a bit in full sun so partial shade would be ideal.

NEW ZEALAND FLAX

Another New Zealand native, Phormium tenax (New Zealand flax), does extremely well in pots, as do its various cultivars and hybrids. Listed in most books as hardy to zone 8, they appear to be hardy to zone 7 in our area. Phormium ‘Duet’ looks very handsome on its own in a container. Since they have quite aggressive root systems, they are best grown this way, and it makes it quite easy to wheel them into the garage during the coldest months, usually mid-December to mid-February. And remember to keep to keep them near the window as they are evergreen and need the light. While there have been several winters where it has been quite safe to leave phormiums out if you live in some of our province’s warmest zones, the last two winters dipped to particularly cold temperatures for a couple of days and phormiums still outside were badly frosted, requiring some very careful selective pruning of the damaged foliage and a good deal of time for a total recovery.

The common name of phormium comes from the strong fibre in the leaves. The Maori used phormium to make their skirts: long mature leaves were collected in 3-cm (1-in.) sections cut at right angles across the leaves; then the outer flesh of the leaves was scraped away to expose the fibres. Finally, they were dipped into the hot geyser pools around Rotorua. The hot water makes the leaves curl inwards, producing what looks like strings of large beads. Sewn together with a top band they were used to make lovely skirts.

Sempervivum

Sempervivum

One more low-maintenance group of plants for sunny patios includes the various species of Sempervivum, often called hens and chicks or houseleeks, and sedums. Pictured at left is a dark-red Sempervivum called ‘Booth’s Red’. A smaller one is S. arachnoideum, often referred to as the cobweb houseleek. These plants are extremely resilient and hardy. They are listed in books as hardy to zone 5 and up, but I have seen them growing happily in Calgary and Saskatoon and would suggest they can take zone 4. The golden sedum is S. makinoi ‘Ogon’, which prefers protection from hot afternoon sun (zone 6), and the silvery foliage belongs to Sedum spathulifolium ‘Cape Blanco’, an Oregon native. (zone 5).

They are ideal for growing in wide shallow pots filled with freely draining soil, and mixing different forms and cultivars together can create a tapestry of colour. The nice thing is that once they are established you can go away for a couple of weeks or longer in the summer and they will still be happily growing on your return, as their succulent leaves store moisture.

The common name houseleek comes from the British Isles, where these plants were often grown on the slate or tiled roofs of cottages. They were thought to ward off lightning strikes as well as keep evil spirits at bay.

Other foliage plants

Other less hardy but very showy foliage plants include Coleus, Canna and Caladium, all of which can be seen in the picture above with the lily.

Coleus has been reclassified and is now known as Solenostemon scutellariodes. Though this has become the correct botanical name, I have a feeling it will be commonly known as coleus at most garden centres for a season or two yet. Coleus has quite distinctive foliage resembling a nettle, giving it the common name of painted nettle. The upside is they don’t sting! These shrubby annuals are native to southeastern Asia, and according to the RHS Plant Finder there are over 150 cultivars. They make perfect plants for a semi-shaded patio. Coleus require humidity and warm nights to perform at their best, so they don’t do as well out here at UBC, where we experience pleasant cool northwest breezes from Georgia Strait. In inland areas like the upper Fraser Valley and the Okanagan, coleus would do extremely well in mostly shady situations. I understand there are sun-tolerant coleus available these days. I haven’t grown them myself but would assume they still need the warmer nights to perform well.

Solenostemon roots easily from cuttings, which should be taken in late July/early August. Treat the plants produced from them as houseplants over the winter and they’ll be ready for planting out the following season. On the patio they need plenty of moisture and biweekly feeding with a small amount of liquid fertilizer (see the note on care of annuals below).

‘Striata’, also called ‘Pretoria’ or bengal tiger, was imported into the U.S. from India in 1963. There are many hybrid cultivars of these plants, some with very striking foliage and flowers that give the feeling of being in a tropical jungle. Their rhizomatous roots are so vigorous that I suggest growing them in their own pots, which should be 45 cm (18 in.) in diameter or larger. This tropical plant is widespread throughout Central America. It’s pretty easy to care for and can take a little frost, which usually blackens the top leaves. These can be trimmed back immediately and the whole pot wheeled into an unheated garage for the winter.

Under the canna you will see the small, arrow- or heart-shaped leaves of two cultivars of Caladium bicolor. These tropicals really need heat, and in all honesty, if you want to see them do their stuff outside, go to central Canada where the summer humidity takes some getting used to. Caladiums lap it up. While they are wonderful plants, they wouldn’t be my first choice for B.C. I say this knowing that some of our readers out there are likely doing quite well growing them.

Let’s just finish up with a few tried and true patio favourites. I am traditional and still love daisies, lobelia and parsley, all of which are great performers in pots and produce happily all season long. I like to group three pots at different heights, one with all white daisies, another with solid-blue trailing lobelia and the third full of curled parsley with its fresh green foliage. This simple combination gives visual joy and also provides fresh parsley for the kitchen.

A pot full of bright-yellow marguerite daisies, called Argyranthemum ‘Butterfly’, add a splash of cheerful summery yellow, but I especially like white marguerite daisies, such as ‘Donington Hero’ and ‘Chelsea Girl’, a selection of the species A. gracile, which has much finer foliage. My friend Carolyn Jones tells a funny story about these plants. While working at VanDusen Botanical Garden and hosting an international conference, she asked English visitors about the origin of a double-flowered marguerite listed in English references as ‘Vancouver’. They sighed and said that one of their colleagues had brought a cutting of it from Vancouver back to England, quickly jotting Vancouver on the label as a reminder. The name, which is not its original name, stuck and it has since won an Award of Garden Merit from the Royal Horticultural Society.

Other favourites include Salvia patens (gentian sage), which is native to Mexico and has large, intensely-blue flowers. While it is not hardy, it forms small tuberous roots that I overwinter in the cold frame. I repot them into some fresh potting soil in the spring and they give a succession of vivid flowers all summer.

I usually mix a pot or two of bright-orange gazania among them. These natives of South Africa are great for hot sunny spots. I am also very fond of another South African native, Osteospermum ‘Orange Symphony’.

Note: Once the summer annuals mentioned in the latter part of this article are well established and the roots fill the pots, keep them well watered and add a small amount of liquid fertilizer such as liquid seaweed or fish fertilizer (about a quarter of the strength suggested on the manufacturer’s label) each time you water. This will give the plants the energy they need to keep blooming well into the fall.

The following plants are hardy to the zone number indicated (turn to page 6 for our zone chart): Acaena microphylla (bronze New Zealand burr) – zone 6 • Agapanthus (African blue lily) – zone 7 • Argyranthemum ‘Chelsea Girl’ – zone 10 • Astelia chathamica syn. A. nervosa var. chathamica – zone 8 • Brugmansia (angels’ trumpets) – zone 9 • Canna ‘Striata’ – zone 8 • Dryopteris wallichiana (Wallich’s wood fern) – zone 10 • Gazania – zone 8 • Helichrysum petiolare ‘Limelight’ (licorice plant) – zone 10 • Ipomoea batatas ‘Ace of Spades’ – zone 9 • Linaria (toadflax) – zone 5 • Lysimachia nummularia ‘Aurea’ (golden creeping jenny) – zone 4 • Nicotiana sylvestris (tobacco plant) – zone 10 • Osteospermum ‘Orange Symphony’ – zone 10 • Pennisetum setaceum (fountain grass) – zone 9 • Phormium tenax (New Zealand flax) – zone 9 • Phormium ‘Duet’ – zone 9 • Pinus mungo (mountain pine, mungo pine) – zone 3 • Salvia patens (gentian sage) – zone 8 • Sedum adolphii makinoi ‘Ogon’ – zone 6 • Sedum spathulifolium ‘Cape Blanco’ – zone 5 • Selaginella (treelet spikemoss) – zone 8 • Sempervivum (hens and chicks) – zone 5 • S. arachnoideum (cobweb houseleek) – zone 5 • Yucca filamentosa ‘Bright Edge’ (Adam’s needle) – zone 5 • Yucca gloriosa ‘Variegata’ – zone 7

David Tarrant of the UBC Botanical Garden is a well-known gardening expert, author, and host of Spring, currently on HGTV.