As belting hot summer temperatures descend upon us we gardeners start thinking about how to protect our precious trees and plants from the furnace. It is often repeated that summer vegetables need full sun and…. blah, blah, blah….. Sorry. I stopped listening at some point. Australia is a hot country. These “rules” have been established for cooler climates. In Australia our tomatoes might get sun scald on a hot summer’s day if they are getting the accepted “at least 8 hours of full sun”. I never follow the crowd. I constantly push those boundaries and try to blaze my own trail. I have successfully got a bumper crop of capsicum off a plant that was growing in the shade of a pine tree and receiving approximately 1-2 hours of morning sun. One branch was so laden with fat, juicy capsicum that the branch snapped! Oh but it was a bitter-sweet victory for me. Now let me elaborate about our summers. I am talking about the climate in the Sydney area. I realise that the conditions in Tasmania are far removed from what is the norm for Northern Queensland. All I’m saying is: Don’t follow the rules blindly, sure you can use them as a guide but then go outside and do what is best for your garden given the conditions you are faced with. Note that the ideas below are not necessarily going to be the best (or only) option for you. They are there to provide you with something that you may not have considered before. What has worked for me may not work for you in your given conditions. And now, for some tips on how to summer-proof your garden, read on.
- Avoid putting plants in pots – unglazed terracotta pots are porous and therefore dry out more quickly, black pots attract heat which warms the soil. If you do have plants in pots, move them to a shadier position during exceptionally hot weather.
- Protect your plants with a “nurse” tree. Plant a hardy shrub to the west of the plants you want to protect so they are shaded from the worst of the western sun. A good choice is one of your local wattles which will generally grow quickly, need no looking after, and fix nitrogen from the atmosphere (you can use them for “chop and drop” fertilizer/mulch). Using a local wattle also ensures that the correct rhizobium bacteria are already present in your soil for the wattle to create the symbiotic relationship required for the nitrogen fixation.
- Bare soil dries out very quickly so use mulch on the ground around your trees and veggies, or plant groundcovers. Planting a groundcover that is thick in summer but dies back in winter is a good choice if you want something that will provide nutrients and biomass to the soil as the plant dies back.
- Practice long stem planting for deep root systems. With this method you plant seedlings with about three quarters of their length below the soil surface (may be up to 1 metre deep for some trees). The deep planting allows the plant better access to soil moisture. Once planted, the seedling develops roots from the buried stem and leaf nodes. This promotes the development of a robust root network which gives the seedling a greater chance of survival. Note that this method generally works for plants which are easy to propagate from cuttings. I have read that you should NOT use this method for grafted trees – now isn’t that a red rag to a bull? You can be guaranteed that I WILL be trying this method on grafted trees in the near future… just blazing my new trail….
- Do not water your fruit trees. Oh yes! I heard the collective gasp of surprise. How on earth could I be telling you NOT to water your baby fruit trees when everything you read is telling you the exact opposite (to water deeply)? Ok. So let me elaborate “Do not water your young fruit trees UNLESS YOU ARE ABSOLUTELY SURE THAT YOU ARE WATERING VERY DEEPLY”. The Dept of Agriculture (Victoria) says a newly planted peach tree with a 75mm butt circumference will require weekly water of 99Lt during hot weather in early January. That is 10 buckets of water! Now I live exclusively on tank water and I know that I am not going to be able to provide THAT much water to the many fruit trees that (mysteriously) keep springing up all over my property. Are you really watering your trees enough? Of course, factors such as the condition of the soil, how much rainfall, and the amount of evaporation all play a part – but it gives you the idea. If you are anything like most gardeners you will stand at your fruit tree with a hose. The first tree might get a good drink and then you tire of that and move to the next tree. The second fruit tree gets a little less water before you become bored and move on to the third tree. After several trees you find that you are only watering for a very short time on each tree…. This is NOT a deep water. This can be worse for the tree than not watering at all. The tree is encouraged to grow shallow, surface roots to stay where the water is. They never have to dive their roots deep into the soil searching for water… I think you can see where I am going from here… If you do not water your trees they will grow a deep root system searching for water. Note that when fruit trees are first planted it is important to not let their root ball dry out. This may be the time when some extra watering (deep watering) is required. But if you don’t plant your new trees in summer then the risk of drying out is much reduced. I watch my trees for signs of heat stress such as leaves curling upwards at the outer edges, wilting, drying up and turning brown, leaf drop, or flower/fruit drop and that is the only time I might consider giving them a very good drink. This might only happen once or twice a summer during a particularly dry, hot spell but my fruit trees are still very young and I expect this watering to be needed less and less as my trees mature and their roots become deeper each year.
- Use watering alternatives that are more passive rather than watering by hand. Use a soaker hose or drip irrigation. Dig swales. Use deep pipe irrigation. Build a hugelkultur mound. Build a wicking bed.
- If you simply must water, don’t do it during the hottest time of the day when evaporation will be at its maximum. Consider watering your fruit trees AT NIGHT (yes, I heard yet another gasp of surprise). I know we have been told for forever that we shouldn’t water at night due to mould and mildew issues BUT plants stop transpiring at night which means that they also stop (or slow) the uptake of water from their roots. This means that any water that you put onto the soil at night time will soak in nice and deep and create a “water plume” that extends well beyond where it would have if you had watered during the day. This creates a situation where your fruit trees will extend their root system further in order to obtain the water – and the bigger root system makes them more drought tolerant. And just something to think about – I am pretty sure it rains at night time… Hmmm…
- Teeny tiny new baby seedlings have a very shallow root. These guys will probably need some looking after. Keep a close eye on them and provide them with a little extra care if necessary.
- Remove the fruit from fruit trees for the first few years. Producing flowers and fruit takes a great deal of energy from the plant. In the wild, a tree would grow from a seed and have many, many years of growth and will have built up a strong root system before it produces any fruit at all. In today’s gardening world of grafting and transplanting, trees which are way too young and with an under-developed root mass are already producing fruit. As hard as it is (a baby apple is so damn cute!), remove the fruit from your tiny fruit trees and let them put all their energy into growing a big, strong root system instead. They will thank you for it for many years to come.
- Protect your garden and trees from wind. Summer winds can be extremely drying. Plant a wind break to baby your babies.
- Put up shade cloth. The western sun can be particularly fierce. Protect from the west as well as above.
- Do not prune fruit trees back just before the peak of summer. The extra leaf cover will protect your tree from the worst of the heat and will also provide much needed shade for smaller plants below.
- Do not allow grass to grow around your fruit trees or into your garden. Grass is highly competitive of nutrients and water reducing the availability for your plants.
- Choose plant varieties wisely. Accept that some plants just ain’t gonna work for you in your climate. Don’t waste hour upon hour trying to pander to the needs of a plant which is just not appropriate for your conditions. You will not get it to truly thrive. Find something more suitable and sit back and reap the rewards.
- Think carefully before planting against a wall with high thermal mass (such as brick) or high radiant heat (such as Colorbond). If these fences are causing additional unwanted heat in summer, you may need to place something such as cardboard up against your fence to provide some insulation and protection for your plants.
- Promote mycorrhizal fungi by using no-dig methods. Mycorrhizal fungi work in a close relationship with your plant’s roots to extend their root zone. The fungi extend well beyond the plant’s roots and bring water and nutrients to your plant. Tilling the soil kills these beneficial fungi.
- Try planting those plants in a little more shade than is recommended by the “gardening guru’s”. You never know, you might be surprised. Plants have various shade tolerances and sure, that capsicum might grow a little more slowly and it’s fruit might take just a little bit longer to ripen, but grow it will! And in the process you might just have used a corner of your garden that would have otherwise been neglected. And you will have blazed a new trail of your own…
Now run outside and create your oasis!