We all know that feeling when the mercury edges over 35C – we just want to find as cool a corner as possible and laze the summer away. Everything becomes too much effort and the only sensible action seems to be to do nothing! Humans and other animals feel it too and, of course, many of our plants.
This feeling is a process for survival in extreme conditions, a temporary inactive phase. Just as many plants, animals (and maybe some humans too!) hibernate during winter there are also some that become summer dormant – known as aestivation. The word stems from Latin aestasor summer and is also sometimes spelt estivate. When conditions become unfavourable because of high temperatures and aridness, – the hot, dry season – plant metabolism comes, virtually, to a standstill. Mother Nature provides them with the most important protection – dormancy. In order to avoid desiccation, they have various other protective devices to increase their likelihood of survival such as grey/white leaves to reflect some of the strength of the sun’s rays; hairs and felted or very leathery leaves do the same thing and this also, coincidentally, makes them very resistant to insect attack.Needle-like leaves reduce transpiration and some plants have learnt to fold their leaves up or twist them for the same effect. Cacti and succulents are, of course, the masters of summer as are various trees with swollen trunks to store water, just like camels.There are also many other plants that will store up water, nutrition and carbohydrates to use to sustain themselves during aestivation. Growth will stop and the plant can even appear dead, but it is not! Many of our Mediterranean plants have adopted this habit and they will come into new growth in autumn, produce leaves, flowers and seed through the, relatively, mild winter and spring. They are ‘topsy-turvy’ with plants from cooler climates.
Even the most skilled gardeners can be tempted into trying to produce lots of summer flowers – after all, it’s the time we want our gardens to look their best. Northern Europeans, for example, are conditioned to expect their plants to look their best in summer – often, here, it can be very different.So it’s important to know the plants that simply want to rest when the going gets tough! Summer irrigation, for some of our best-loved Mediterranean plants, can be detrimental and even prove fatal.
Grouping plants according to their watering needs is one of the most vital jobs you can do in your garden and it should be the first step in any garden design. Don’t mix these summer dormant plants with lush tropical plantings that are very demanding of water, for instance, – the two groupings will clash and only cause you problems. I often hear people saying that they cannot reduce the water to a specific plant because it is on a system with much more thirsty things. This is bad planning and bad design and it needs to be addressed to make your gardening life simpler. Once you have sorted your plant groupings, generally into three types – dry, medium water requirements and heavy water requirements – you can then choose the plants and ‘the look’ that you desire within those groupings. In practise, it is often sensible to have plants with heavier water needs closer to the house and the dry-area plants further away. This, usually, works well in terms of looks and practicality.
To help you do this, here are some of the plants that are summer dormant – expect them to look ‘sad’ during summer.
Firstly there are those which go completely underground in summer and many of our bulbs, corms, rhizomes and fleshy rooters fall into this grouping. So things like cyclamen, narcissi, tulips, acanthus, alstroemeria and capers.
There are many others that simply stop growing and sleep through the hot summer season. Here are some:
Abelia, abutilon,akebia, albizia, arctotis, artemisia, caesalpinia, campsis, ceanothus, cistus, clematis armandii, clematis montana, cordyline, coronilla, cytissus, dimorphotheca, echium, eleagnus, erythrina, euphorbia, fremontodendron, hypericum, indigofera, ipomoea indica, lantana, lavandula, lonicera, jasminum, lonicera, mahonia, melianthus, nerium oleander, olea, osmanthus, parthenocissus, photinia, pittosporum, prunus dulcis (almond), raphiolepsis, rosmarinus, salvia, solanum, tipuana, trachelospermum.
There are many, many more so please don’t treat this list as definitive. I merely want to give you an idea of the vastness of the grouping, give hope to dry gardeners and let us all appreciate and relax into summer aestivation!
Have a meltingly hot good summer and please remember that the Garden Centre is closed – or aestivating – during August. We’ll be back in September, green, lush and burgeoning with autumn energy!
Lorraine Cavanagh owns the specialist garden centre ViverosFlorena, Competa, Malaga (garden centre, designers & landscapers) and is author of the best-selling Mediterranean Garden Plants. m
