In the garden: Beating the heat with plants for hot, dry summers 

Russian sage is one of the best perennials for hot dry summers.  Photo by Claire McCaughey

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There is no doubt that weather patterns are changing because of climate change. Summers are hotter, and at the same time there are more extremes of weather with too much or too little rain. This new normal requires gardeners to adapt. Improving soil health, mulching and using water more efficiently have become increasingly important. In addition, many gardeners are looking at their plant choices as a strategy to deal with changing climate, especially the combination of heat waves with droughts. 

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Characteristics of tolerant plants 

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Plants that adapt to both heat and drought have a variety of characteristics that make them more resilient. Plants with grey or silver leaves have fine hairs on their surfaces which reduce the impact of light and heat. Succulent plants tolerate hot temperatures and drought by retaining moisture in their tissues. Perennials and grasses with long tap roots or deep root systems can absorb moisture from deep underground. Plants with narrow leaves are also able to withstand hot dry conditions by reducing moisture lost through leaves. Perennial herbs (especially from Mediterranean regions) as well as perennial vegetables (asparagus, rhubarb) survive well in heat and drought. 

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Growing plants in hot dry weather 

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Most newly planted perennials and shrubs, even the most drought-tolerant, require regular watering in their first year and beyond to establish well. To conserve water, these new plantings should be individually watered. In addition, mulching new and existing plantings helps to conserve water in the soil. Over time, drought-tolerant groundcover plants that spread to cover the soil may take the place of mulch.  

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Annual hibiscus loves heat but requires regular watering and is not drought tolerant. Photo by Claire McCaughey 

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Plants for hot, dry summers  

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The plants listed below will breeze through hot dry summers. However, most will not tolerate wet areas or too much water, so it is important to choose a planting location with good drainage. 

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Grey-leaf and silver-leaf perennials: Purple-flowered Russian sage (Perovskia atriplicifolia); yarrow (Achillea species and cultivars such as ‘Moonshine,’ with a lovely yellow-gold flower) and lamb’s ears (Stachys byzantina). The latter is grown more for its foliage than its flowers. 

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Mediterranean herbs: Culinary sage (Salvia officinalis), thyme (Thymus vulgaris), lavender (Lavandula officinalis), and oregano (Origanum vulgare). There are cultivars of all these herbs that are valuable for both culinary and ornamental purposes. Hot dry summers are characteristic of the Mediterranean region and similar areas elsewhere in the world such as California. While our winters preclude growing many of these plants some are hardy enough for our climate (or are borderline hardy).  

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Hardy succulents:  Tall fall-blooming stonecrops (Hylotelephium) and groundcover sedums. Two popular cultivars are stonecrop ‘Autumn Joy’ (Hylotelephium) and sedum ‘Angelina’ (Sedum rupestre) with beautiful golden foliage. Both grow well in full sun and rarely need watering. There are many succulents that are not hardy (such as aloes, agaves, and snake plants) but which are useful annuals for hot dry summers and can be brought indoors as houseplants for the winter.