Plants for the Summer Dry Garden

Like many of you I have my favourite plants, which despite knowing that they are not well suited to my soil or climate I am stubborn enough to persist in trying to grow. For me that is my hedge of lacecap Hydrangea. With our very light, low nutrient and free draining soils, it requires quite a bit of work to keep them hydrated enough through a typical Hawke’s Bay summer. The Cistus on the other hand thrives in full sun, not a drop of extra water, and even better in the 6 years they have been in the ground they have never needed pruning. Planting more of the types of plants that thrive in the soil and climate you have is easier and less stressful to both the gardener and the plants. Other than persisting with the Hydrangeas, which I expect will eventually go, it is far more sustainable and sensible to focus extra water on the plants that produce our food. That doesn’t mean we must deprive ourselves of a garden that is both beautiful and a haven for wildlife.

Start with what you have

Whether you are starting a garden from scratch or working with an established garden, the greatest success comes from understanding all of the ingredients you have to work with. At Bee Haven Gardens soil type is alluvial gravels, and though some areas of what is referred to as the Ruataniwha Plains have clay layers, I am yet to find even a spoonful of clay here. The soil drains exceptionally well, and I have been known to suggest “It is like gardening at the beach but with frosts”.

Good drainage has its advantages as most plants don’t appreciate their roots sitting in water for long, but a little water retention would be appreciated. Being an open plain with the Ruahine range to the west also exposes the garden to drying winds, though the garden here has the benefit of 30 years of tree planting for shelter – thank you Pete.

Wind has both advantages and disadvantages. Wind increases the rate of evapotranspiration as well as the more obvious negative effects of damage to trees and other tall plants and general unpleasantness for working in. The advantage is that many of the plants we grow need good airflow particularly during cooler wet conditions. Many of the plants discussed here are native to places where exposure to wind is common, making them perfect if you have more exposed gardens, or shelter is not yet established.

A summer dry plant selection. The New-Zealand native flax provides good shelter from cold winds.

Our annual rainfall average is about 800 mls, with the drier years getting between 600 and 750 (737 mls for 2024). When rain falls can be just as important for plant selection as the rainfall total. The Hawke’s Bay climate is traditionally viewed as experiencing cool wet winters and hot dry summers. Many a local farmer has traditionally relied on good spring rain to establish crops and grow grass to fatten stock before the usual warmer dry summers take effect. With the growing unpredictability of weather patterns, this may not always be the case. This is an important consideration during the establishment phase of planting. Even plants chosen for their dry tolerance require water to get them going. Giving plants the best chance to get their roots established is even more important for those that may be expected to survive periods of drought. This is when deep watering is more effective than lots of light watering. Deep watering encourages roots downwards. Roots that grow close to the surface will dry out quickly when hot dry or windy weather arrives.

Also to consider, is temperature. High temperatures increase evapotranspiration-the rate at which water leaves the earth surface through the processes of evaporation and transpiration. In December we experienced several days with temperatures in the low 30s and accompanying wind as well. Water restrictions in our local urban areas were in place quite early in the season too. By choosing plants that suit drier conditions we not only create something beautiful, but we can also reduce the burden on our precious water resources. While we are not affected directly by the water restrictions that our urban neighbors experience in Hawke’s Bay, water is a valuable resource that we cannot afford to squander.

Plant origins

As well as understanding the climate and soil in your garden to inform your plant choices, knowing where the plants come from – the native environment the Genus – and sometimes more specifically the species – originate from, is a useful tool. Much of my initial plant selections come from the Mediterranean or more precisely that which is referred to as ‘Garrigue’– an ecoregion characterised by rocky open scrubland with annual summer drought. Similar bioregions exist in other parts of the world – In California ‘Chaparral’, Chile ‘Matorral’, in South Africa ‘Fynbos’ and in Australia ‘Mallee’. Each of these regions offer a wide selection of plants particularly well adapted to the summer dry garden.

A typical ‘Garrigue’ landscape

Wild Plants

Another useful tool for identifying plants which are potentially suitable for the summer-dry garden is by observing which plants are growing wild in the area and thriving. Some of these maybe classed as weeds but for many of them there are related garden specimens. A great example of this is the common Yarrow -Achillea species. Here in Hawke’s Bay, they are a common plant of roadsides and paddocks. Luckily for the gardener there are many colourful and beautiful relatives for your summer-dry garden.

Achille millefolium ‘Terracotta’

Achillea millefolium pink selection

Achillea millefolium ‘Hella Glashoff’

The table below lists the wild version of plants thriving along Hawke’s bay roadsides, and some of the garden alternatives.

Typical roadside flowers in Hawke’s Bay – Echium, Verbascum, and Primrose.

My Plant Picks

For my top picks I have limited my choices to those plants that have been in the garden long enough for my personal observations on their ability to withstand dry summers to be accurate to this place. I would love to hear your own experiences and top picks.

For beauty and toughness my top pick would have to be the Cistus spp. native to the Mediterranean they are a genus of about twenty species. These plants thrive on poor free draining soils in full sun. Most form rounded compact mounds of varying sizes, of green to grey leaves with gorgeous open flowers in varying shades of pinks and whites. Most need very little if any trimming to maintain their shape making them a great choice for the low maintenance garden. An area of the garden at Bee Haven has been planted mostly in Cistus, and other than being mulched with wood chip, nothing else has been done to them for about 6 years.

A variety of Cistus species

Santolina are another drought tolerant genus from the Mediterranean that thrives best on poor free draining soils in full sun. An observation of Santolina planted in different areas of the garden has been an opportunity to discover firsthand that the common response of “Just give it more water” to an unhealthy plant is often misguided. Several santolina are planted beside the nursery area which often receives extra water from the sprinklers used to water nursery stock. These are young plants which initially established well but have started to collapse in the middle when flowering and tending to leggedness requiring maintenance work (and adjustments to the sprinkler) conversely some older stock that were past being sellable were popped into open gaps on the northern edge of the orchard and have thrived with no water other than that from the sky. Their form is much more compact and have yet to need any trimming even though plants are the same age.

Euphorbia species are a must have for the dry garden. They are a widespread genus from many parts of the globe and include annuals, perennials, shrubs, and even trees. Many will handle extreme drought conditions such as those of desert origins. We are starting to build a small collection of them. I find them useful plants to mix with colourful perennials. They are all particularly attractive to pollinators as well. My top three are: E. characais ‘wulfenii’, E. mellifera, and E. myrsinites.

Euphorbia myrsinites, Euphorbia mellifera, and Euphorbia characais ‘wulfenii’

Though not specific to the Mediterranean ecoregion having the much wider native range of Eurasia, are the Hylotelephium (formally sedum) a must have for the dry garden. Being a succulent, its drought resistant properties are well known. Their beauty, long lasting colour and ease of care ensures they appear frequently throughout the garden. Hylotelephium. telephium ‘Autumn Joy’ is my favourite mainly for the stiff upright bricky brown flower heads that last all winter long until I decide to cut them down in spring as the lovely new mounds of leaves emerge.

Hylotelephium. maximum I have observed makes a surprisingly attractive groundcover for dry shady areas, though flowering will be very spasmodic. Initially this plant was growing in the garden under trees when I moved here in 2014 – though it took me awhile to Identify it correctly, particularly as I rarely saw it flower. Thus, the reason for knowing its ability to handle dry shade.

foliage of Hylotelephium maximum and flowers of Hylotelephium ‘Autumn Joy’

Helichrysum are a large genus that feature many plants suitable for the dry-summer garden. Helichrysum petiolare native to the Fynbos region of South Africa was originally one of those suggested, though having since discovered its inclusion on plant pest lists in NZ and seen myself how quickly it can colonize dry areas, I have removed it from my list and nursery. Luckily there are other beautiful plants in this genus that make wonderful garden specimens including the curry plant – Helichrysum italicum , Strawflowers Helichrysum bracteatum and several endemic New-Zealand species including H. coralloides, H. simpsonii, H. plumeum, H. parviflorum.

Helichrysum italicum and Santolina

Xerochrysum bracteatum (formally Helichrysum) and Agastache rugosa f. albiflora

New-Zealand Natives

A beautiful New-Zealand native that has thrived here with total neglect, full sun and particularly poor soils is Pimelea prostrata a beautiful silvery leaved groundcover which smothers itself with sweetly scented white flowers. It also competes well with weedy grasses which have colonized this particular area of the garden. This could suggest it has some allelopathic properties which interestingly several of the Mediterranean plants also have as a mechanism for reducing competition. New-Zealand has about 36 species of Pimelea and there are more of this genus in Australia, quick research shows some of them to be from the drier regions such as the Australian mallee.

The beautiful NZ native Pimelea prostrata

I must include grasses among my top picks for the dry garden. While there are many popular grasses from around the world that have become a feature in the popular naturalistic garden styles that I take much of my inspiration from, it is using New-Zealand native grasses that I am most interested in, here are my dryland favourites.

Poa cita silver tussock grass, Anemanthele lessoniana, wind grass, Carex testacea, Chionochloa flavicans miniature toitoi and Festuca actae blue fescue

Anemanthele lessoniana – NZ wind grass

Some might consider it overdone being a common sight in public plantings but for good reason the top pick for dry shade would have to go our native Rengarenga lilies Arthropodium species I don’t believe its commonness detracts from its beauty or hardiness.

There are many more shrubs and perennials of Mediterranean origins that I have planted in my sunny dry areas which are likely well known to most of you but not to be excluded from the list. Within the following genus there are many species and varieties that add colour and interest to the summer-dry garden, Rosemary, Phlomis, and Oregano. Interestingly rosemary in its native environment will drop its leaves in extreme droughts as a mechanism for surviving till rains arrive.

A mixture of summer dry plants: oregano, thyme, grevillea, and grasses

Salvia

Many of you will well know that I have become rather addicted to collecting Salvia species and while there are many that do best with some moisture in summer, there are still plenty to choose from for the summer dry garden. Currently I am experimenting with quite a few new varieties that I have chosen especially because their origins suggest they should be dry tolerant such as S jurisicii and S. azurea, for the sake of this article I will only list those that have been well tested here.

Salvia officinalis (green sage as well as S. officinalis purpurea– purple sage), Salvia. sclarea Clary sage, Salvia nemorosa, Salvia greggii

Salvia nemorosa ‘blue Queen’

Salvia greggii -Rose

Australian Grevillea species are another great option for the dry garden with the bonus that they are great nectar plants for birds and insects particularly at the end of winter and early spring.

Many dry tolerant plants have some obvious adaptations to help them cope with low rainfall. For example, the narrow leaves that can be found on plants such as rosemary – Less leaf surface area means less water loss. Another adaptation is the silvery grey leaf colour, -often accompanied by fine hairs – that reflects sunlight rather than absorbing it. It then can be even more surprising when we discover plants that show none of these obvious characteristics yet display excellent dry tolerance one of those is Choisya ternata with its glossy large green leaves and beautiful creamy blossom, it definitely has the appearance of a plant that requires regular water. Native to Mexico they thrive in wilder parts of the garden with little to no care.

Grevillea ‘Canberra gem’

Choisya ternata foliage

Top trees

My list would not be complete without including some trees. Oaks Quercus species are the predominant species planted near the house. These have lived through a few droughts having been planted over 30 years ago. They were initially watered only to establish (first two years by hand) Now thriving with many over 30 meters tall and well established providing much needed shade. Oaks are a very diverse group with species native to many different climates on all the continents except Australasia and Antarctica. There is bound to be several varieties suitable for whatever climate and soil type you have. Early plantings here were predominantly of Quercus. cerris, the Turkish Oak, though I suspect some trees have Holm Oak Quercus ilex in their parentage. Oak trees have another advantage in a dry climate in that they are noted as being fire resistant. Hopefully they are never tested.

Proven to handle the dry and provide effective windbreaks are the Himalayan Cedar Cedrus deodara. A far more attractive option than the ubiquitous Pinus radiata. Native to the western Himalaya’s they are tolerant to strong winds making them particularly useful as a windbreak. With their graceful Pyramidal shape and soft grey green foliage, they are particularly attractive too.

A lesser-known tree that is proving to be a worthwhile addition to the dry garden is the Soapbark tree Quillarja saponaria. Native to Chile it is a typical species of the Matorral ecoregion and has been used in Chile for reforestation of arid soils. An evergreen tree to 20 meters it is a stunner, particularly in summer when it is smothered with gorgeous creamy lime flowers which have proven to be a favourite source of nectar for our own admiral butterflies, honeybees, bumblebees, hoverflies, and euchemon wasps. I currently have two well established trees in a hot exposed area of the garden and am now very keen to plant some more.

Quillarja saponaria

Context is important, what may be drought to us here in Hawke’s Bay could be quite different in other parts of the country, and also in gardens with different soil types. Your own observations and records will be invaluable to inform your plant selections.

Happy plants beget happy gardeners.

Further reading

Olivier Filippi “Planting Design for Dry Gardens” and “The Dry Gardening Handbook” or any books by Olivier Filippi

Beth Chatto. “Drought-Resistant Planting” Lessons from Beth Chatto’s Gravel Garden

Noel Kingsbury and Claire Takacs “Wild” The Naturalistic Garden

Louise Phillips

With 15 years running a gardening business plus a few years going back to my original career as a teacher, I decided to follow my heart and open a plant Nursery from home. I feel very privileged to be able to work from home doing what I love best: growing plants and creating gardens.

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