Plants in containers will always be at a disadvantage when it comes to water. Without the insulating earth to protect them, their roots can dry out quickly in summer heat.
Succulents and other desert plants are well adapted to hot, dry conditions, making them the default option for drought tolerant containers. But experience has taught me that many perennials, shrubs, and annuals will graciously accept a more relaxed watering schedule than the daily drench that many potted plants require. The containers on the following pages contain some of my favorites, which should need to be watered only once or twice a week, even during the hottest days of summer.
A cool collection of foliage shines in the shade
Siting containers out of direct sun is a great water-saving strategy; soil stays cooler, so there’s less evaporation. All of the plants in this foliage-focused grouping will thrive in your favorite shady retreat from the summer heat. Convex-leaf Japanese holly, foxtail ferns, and ‘Big Blue’ lily turf lend verticality and lovely fine leaf textures. ‘Silver Heart’ brunnera, ‘Green Spice’ heuchera, and ‘Snow Fever’ hellebore all offer shimmering pale leaves and remarkable toughness. Dark notes are provided by black mondo grass and ‘Black Scallop’ ajuga.
1. Convex-leaf Japanese holly (Ilex crenata ‘Convexa’, USDA Hardiness Zones 6–9)
2. ‘Silver Heart’ brunnera (Brunnera macrophylla ‘Silver Heart’, Zones 4–8)
3. Black mondo grass (Ophiopogon planiscapus ‘Nigrescens’, Zones 6–11)
4. ‘Ralph Shugert’ periwinkle (Vinca minor* ‘Ralph Shugert’, Zones 4–9)
5. ‘Snow Fever’ hellebore (Helleborus argutifolius ‘HGC Snow Fever’, Zones 7–9)
6. ‘Big Blue’ lily turf (Liriope muscari ‘Big Blue’, Zones 5–9)
7. ‘Black Scallop’ ajuga (Ajuga reptans ‘Black Scallop’, Zones 3–9)
8. Foxtail fern (Asparagus densiflorus ‘Meyers’, Zones 9–11)
9. ‘Green Spice’ heuchera (Heuchera americana ‘Green Spice’, Zones 4–9)
Sunny yellow shines against blue and silver
Fine-textured foliage is the focus of this container trio. Displaying a water-wise specimen like the potentilla in its own pot is a good way to make a container combination even more drought tolerant.
1. ‘Torbay Dazzler’ dracaena palm (Cordyline australis ‘Torbay Dazzler’, Zones 9–11)
2. ‘Lemon and Lime’ mirror plant(Coprosma ‘Lemon and Lime’, Zones 9–11)
3. Golden oregano (Origanum vulgare ‘Aureum’, Zones 4–9)
4. ‘Blue Star’ juniper (Juniperus squamata ‘Blue Star’, Zones 4–8)
5. ‘Happiness’ euonymus (Euonymus japonicus ‘Happiness’, Zones 6–10)
6. Daisy bush (Brachyglottis greyi, Zones 8–10)
7. ‘Ellwood’s Pillar’ false cypress (Chamaecyparis lawsoniana ‘Ellwood’s Pillar’, Zones 5–9)
8. ‘Moonbeam’ coreopsis (Coreopsis verticillata ‘Moonbeam’, Zones 3–9)
9. ‘Quicksilver’ hebe (Hebe pimeleoides ‘Quicksilver’, Zones 8–11)
10. Christmas bush (Baccharis magellanica, Zones 7–9)
11. Mango Tango™ potentilla (Potentilla fruticosa ‘Uman’, Zones 3–7)
Chartreuse steps into the limelight
Carefree ‘Green Spire’ euonymus creates a dense, deeply colored backdrop for the frilly leaves of ‘Mrs. Pollack’ geranium and the bright rays of ‘Green Jewel’ coneflower. The variegated hebe, heather, and Carmel creeper continue the lime-green theme, highlighted by the sparkling blooms of Diamond Frost® euphorbia and dusky ribbons of black mondo grass.
1. ‘Green Spire’ euonymus(Euonymus japonicus ‘Green Spire’, Zones 6–9)
2. ‘Pinocchio’ hebe (Hebe ‘Pinocchio’, Zones 8–10)
3. ‘Mrs. Pollack’ geranium (Pelargonium ‘Mrs. Pollack’, annual)
4. Variegated Carmel creeper (Ceanothus griseus ‘Diamond Heights’, Zones 8–10)
5. Black mondo grass (Ophiopogon planiscapus ‘Nigrescens’, Zones 6–11)
6. Diamond Frost® euphorbia (Euphorbia hypericifolia ‘Inneuphdia’, Zones 10–11)
7. ‘Green Jewel’ coneflower (Echinacea purpurea ‘Green Jewel’, Zones 3–8)
8. ‘Anouk’ heather (Calluna vulgaris ‘Anouk’, Zones 4–8)
A moody pink links darkness and light
The subtle, smoky pink of ‘Sahara’ gloriosa daisy could easily be overlooked next to brightly colored companions. But with two-toned ‘Firebird’ hyssop and ‘Kent Beauty’ oregano playing backup, this color combination sings. The inky leaves of crape myrtle, fountain grass, and sweet potato vine lend depth and drama, while ‘Tricolor’ hebe adds just the right amount of light.
1. Midnight Magic™ crape myrtle (Lagerstroemia ‘PIILAG-V’, Zones 6–9)
2. ‘Firebird’ hyssop (Agastache ‘Firebird’, Zones 6–10)
3. ‘Tricolor’ hebe (Hebe ‘Tricolor’, Zones 8–11)
4. Purple fountain grass (Pennisetum setaceum* ‘Rubrum’, Zones 8–11)
5. ‘Sahara’ gloriosa daisy (Rudbeckia hirta ‘Sahara’, Zones 6–8)
6. ‘Blackie’ sweet potato vine (Ipomoea batatas ‘Blackie’, Zone 11)
7. ‘Kent Beauty’ ornamental oregano (Origanum ‘Kent Beauty’, Zones 6–9)
This sizzling combination can take some heat
Zinnias bloom exuberantly even in the dog days of summer, lending a welcome touch of color to an otherwise foliage-focused design. The coral-orange leaves of Golden Ruby® barberry provide some color echo for the sunset hues of the zinnia. ‘Cabaret’ maiden grass sends up a fountain of bright blades while ‘Irene’ rosemary and ‘Silver Posie’ thyme trail over the container’s edge.
1. ‘Cabaret’ maiden grass (Miscanthus sinensis var. condensatus ‘Cabaret’, Zones 5–9)
2. Golden Ruby® barberry (Berberus thunbergii* ‘Goruzam’, Zones 4–8)
3. Magellan™ Orange zinnia (Zinnia elegans Magellan™ Orange, annual)
4. Boxleaf euonymus (Euonymus japonicus ‘Microphyllus’, Zones 6–9)
5. Irene™ rosemary (Rosmarinus officianalis ‘Renzels’, Zones 8–10)
6. ‘Silver Posie’ thyme (Thymus vulgaris ‘Silver Posie’, Zones 6–9)
Basics: Create a container that uses less water
Choosing plants that are naturally less thirsty is a good first step when building a low-water-use container. Here are some additional strategies:
▸ Pick the right pot
You can maximize the drought tolerance of your container plants by using non-porous pots. All of the pots shown here are high-fired glazed stoneware except for the gray “egg” (photo facing page), which is clayfibre. The mass of a substantial pot helps to keep soil temperatures lower, and a glazed surface prevents water from evaporating through container walls.
▸ Pack the pot with soil
Fill your pots within a few inches of the top with high-quality potting soil. A mix with lots of organic matter will soak up moisture when it is available and serve as a reservoir between waterings. Mulch any exposed soil to reduce evaporation. All of the containers here are mulched with black pebbles, which are both decorative and functional.
▸ Limit the number of plants
The more full of roots a container is, the less drought tolerant it will be. Instead of overfilling a single planter, consider grouping multiple containers with fewer plants in each. Or try adding a few annuals to an initial planting, but do not replace them in subsequent seasons; the shrubs and perennials that remain will grow together and use the pot space. Of course, a single plant in its own pot can stay happy for multiple seasons.
▸ Remember, low water doesn’t mean no water
To keep your plants healthy, establish a watering schedule, and stick to it. For the combos on these pages, a good weekly soak should be enough for all but the hottest weather, when midweek watering may be necessary.
Barbara Libner designs container plantings for Ravenna Gardens in Seattle.
Photos, except where noted: Carol Collins; dreamstime.com
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