Best plants for summer containers

This morning, I was outside watering the containers on the deck and those next to the potager and greenhouse. We had very hot temperatures in Oklahoma last week. One day we topped out at 108° and another, 110°F. We are now back down to the normal mid to low-90s, but Oklahoma’s extreme summer weather proved which were the best plants for summer containers.

Drip irrigation works

Here’s my rundown, but before we start, note that my containers are–for the most part–on drip irrigation. I did plant a couple of large containers in late spring that I water with a hand sprayer. Also, on the hottest days, I watered twice a day. You can either set up your drip irrigation kit on a timer for twice a day or spray them the second time yourself. You simply cannot miss a day and keep your containers thriving. Miss two, and most plants will die in such extreme heat.

Who could blame them?

After temperatures moderate, feed your plants with a granular or liquid organic fertilizer. There are several brands on the market. Heavily watered plants in containers will need a boost of nutrients.

I wrote about how to install a drip irrigation system for containers in my book, The 20-30 Something Garden Guide: A No-Fuss, Down and Dirty, Gardening 101 for Anyone Who Wants to Grow Stuff. Click the link if you’d like to buy the book and learn more.

[Click on the galleries to see the photos enlarged. Many of the plant names are listed in the captions.]

Pilea microphylla, artillery plant, is probably so named because it is as tough as an artillery shell.

This container has both ‘Cathedral Windows’ coleus and black sweet potato vine. Although I bought the sweet potato vine untagged, I believe it to be Sweet Caroline Bewitched After Midnight™ because of the leaf shape. The container also has a spreading verbena, but it’s pretty overwhelmed by the sweet potato vine. I think the container looks great against ‘Princess Caroline’ grass.

Asparagus densiflorus ‘Myers,’ foxtail fern, is another plant that is almost indestructible.

Bullet-proof plants

When planning your containers, my first suggestion would be to incorporate at least one or more bullet-proof plants like those in the gallery, above. This way, you’re assured of having some success. If something else in the pot dies, simply replace it.

Repeat after me, plants die. It’s okay.

‘Snowflake Rose’ geranium and Polygala fruticosa ‘Petite Butterfly’ have both kept blooming sporadically throughout summer. ‘Snowflake Rose’ has splotched variegated leaves. I will be overwintering it in the greenhouse or indoors.

This nutmeg-scented pelargonium (geranium) has such nice blue foliage that seems impervious to heat. It’s a really easy scented geranium to grow.

‘Orange Fizz’ geranium has some dead leaves inside of it, but considering it’s been in full sun all summer so I’m not surprised.

Ecbolium amplexicaule, green swan flower, is from Kenya and one of my favorite plants to grow in containers. It is the green and white corner of the deck this year. I bought mine at Bustani Plant Farm. It is rugged tough.

Plectranthus scutellarioides ‘Peter’s Wonder’ is another favorite coleus I buy or overwinter year-after-year. Although it has very brittle stems, it’s also such a unique color combination.

I’m very surprised scented geraniums and some of the other zonal geraniums–botanically all pelargoniums–have performed really well in containers this year. You may remember from my Instagram posts like this one of ‘Angel’s Perfume‘ and another video introducing scented geraniums that I invested in six or seven scented geraniums in the dead of winter. I’m happy to say that all of my lovely scented geraniums from Colonial Creek Farm are alive and happy. They aren’t blooming much, if at all because it’s too hot for anything to bloom, but they will once temperatures lower into the 80s. I’m especially excited about the blue/silver foliage of the nutmeg-scented one although it doesn’t smell like nutmeg to me. Scent is really so personal.

A unique pelargonium

I bought P. ‘New Path’ from Bustani Plant Farm, and it is still blooming its fool head off in spite of the heat. Steve Owens, the owner of Bustani, put me in touch with Dr. Ernest DeMarie, who created ‘New Path,’ when he was a graduate student working toward his doctorate at Cornell University. As DeMarie wrote in his blog, A Not So Simple Garden, ‘New Path’ is unusual because it is “a tetraploid with a zonal pelargonium called ‘Rio’ as one parent, and a tetraploid hybrid I made at Cornell via tissue culture from a white zonal pelargonium and P. aridum as the other parent.” This parentage explains the different type of leaves you find on ‘New Path.’ Again, from DeMarie’s blog, “It [P. aridum] is a small plant with deeply divided leaves, small yellow flowers, and red tuberous roots. So somewhere in ‘New Path’ lurk genes for yellow color and finely divided foliage.”

I think it’s simply beautiful. You just never know what you’ll find on the Collectors Corner bench at Bustani! I’ll be overwintering this beauty in the greenhouse come fall.

Thriller, filler, spiller formula

I try to follow the “thriller, filler, spiller” formula of planting, first written about by Steve Silk in Fine Gardening magazine, with one tall plant in the center, something shorter in the middle and something to trail down the sides of the container. The photo, above, shows a version of this formula. With the two shades of pink Supertunias, Vista® Bubblegum®, and Vista® Paradise  (2019 release), and the Diamond Mountain™ euphorbia (2019 release), I think this is my favorite container this year. The Angel Face Steel Blue angelonia (2019 release) blooms slowed down in the extreme heat, but it will recover and bloom more as temperatures moderate. The bloom stalks weren’t standing up the way I wanted so I added this tuteur to hold them upright. I like using tuteurs and obelisks to reign in floppy plants. I also deadheaded the angelonia to encourage more bloom spikes later. An upside-down lamp shade would also work as would a peony support pushed into the potting soil, but in this case, I wanted the height of the tuteur.

Below is a closeup of the same container. It deserves two pictures. Proven Winners sent me these trial plants. I think, if I remember correctly, the company wanted us to combine the already outstanding Supertunia Vista® Bubblegum with 2019 introductions in interesting ways. Well, my plant shipment came at the busiest time of the year so I simply put a bunch of them together in one container. I think it turned out very nice. Very nice indeed.

Even though I like the standard TFS formula, I find that a mid-sized plant like Helichrysum italicum, curry plant, with a ring of lime green duranta, makes a pretty bold statement. This container is also a favorite this year. I placed it between larger containers with taller plantings to fill in around it. I just deadheaded the coleus in the pot at the left so it doesn’t look its best now.

Helichrysum italicum, curry plant surrounded by Duranta erecta ‘Lime.’ This picture doesn’t show the best of this plant combination, but it was the best I could get this morning. Taking a photo from the other side made it look like the plants were behind bars as in prison. Ha!

Containers on the other side of the deck grouped together for easy watering. ‘Princess Caroline’ is on the left, and ‘Fireworks’ is in the pot on the right.

Green and white corner of the deck.

Another of my favorite containers–I planted this one later in the season when I found Pilea microphylla artillery plant, Supertunia Hot Pink Charm, Helichrysum petiolare Lemon Licorice, licorice plant and Floria Sun Rose coleus on sale for half price at Acer Hardware. I just knew they would look splendid together, and they do.

Closeup of Supertunia Hot Pink Charm, Blue My Mind Evolvulus, Helichrysum petiolare Lemon Licorice and Attar of Rose scented geranium.

By grouping containers together in pleasing ways, you can use the TFS formula on a larger and more interesting scale.

Tall plants that perform well in my containers are purple fountain grasses like Pennisetum purpureum ‘Princess Caroline’ which takes a very large container and its smaller cousin, ‘Fireworks.’ You can also use plain purple fountain grass, but I like ‘Fireworks’ better. It does lose its pink stripe in the middle of summer but regains it again in fall.

Rugosa roses also make a tall statement in the garden. After they grow larger, they compete with anything else in the pot. Why Rugosa roses? Because they are extremely hardy. I can leave my ‘Therese Bugnet’ out on the deck in a glazed pot all winter. Rugosa roses also smell good.

Cyperus papyrus ‘King Tut’ Egyptian papyrus is another great plant for a container centerpiece in full sun. In fact, most grasses do really well as do large coleus. I just trimmed all of my coleus back by half so they don’t look that great today. ‘Big Red Judy’ also sometimes called ‘Big Red’ is a wonderful large coleus that could be the centerpiece of any pot.

Here’s an old photo from 2011 of Rosa rugosa ‘Therese Bugnet’ with an assortment of desert and tropical plants.

Rosa rugosa ‘Therese Bugnet’ only blooms once in spring in my garden, but she is pretty and smells delicious.

‘Big Red’ coleus earlier this spring.

In the photo below, I’d hoped ‘Large Marge’ coleus would grow larger than the Lotus jacobaeus, black lotus plant in this container. I should have read the tag. Marge isn’t that large The black lotus has a see-through quality, but Marge looks rather smothered. Both plants are extremely drought tolerant, and the black lotus bloomed only a week ago. The blooms are so exotic they give me a thrill.

I know, I know, but really, they do.

When thinking about heat and drought tolerance, look for plants with silvery foliage. I really hate dusty miller, but my friends in Tulsa convinced me broad-leaved dusty miller was a much prettier plant. They were right. Thanks, Beth and Teresa! I’m enjoying how heat tolerant it is and how great it looks against P.  purpurea ‘Princess Caroline.’ It’s also great in bouquets and is often used in the florist industry. Dichondra argentea ‘Silver Falls’ is another a good choice as are the newer varieties of Evolvulus Blue My Mind® and Helichrysum petiolare Lemon Licorice. The latter two spill out of containers and weave through other plants in very pleasing ways.

Senecio cineraria ‘New Look,’ broad leaf dusty miller in front of P. purpureum ‘Princess Caroline.’

Dichondra argentea ‘Silver Falls’ is also a good choice for a hot-weather container.

Closeup of Supertunia Hot Pink Charm, Blue My Mind Evolvulus, Helichrysum petiolare Lemon Licorice and Attar of Rose scented geranium.

With that, I think I’ve covered what worked well this year in containers. Remember, bullet-proof plants are the centerpiece of any successful heat wave container. What are some of your favorites this year?