Helen McKerralGarden diet

Throughout history, we human beings have adopted an amazing variety of diets, for an amazing variety of reasons. We comprise omnivores, vegetarians, ovo &/or lacto-vegetarians. Eggs are variously available as cage, barn, organic, biodynamic and free-range. Some people don’t eat beef or pork, or only eat meat that must be prepared in certain ways. Some exist on a diet of high-calorie, low fibre pizza, burgers, fried chicken and fizzy drinks. Traditional Inuit lived on a high fat, high protein diet of birds, marine mammals and fish, getting their Vitamin C not from fresh fruit but from raw Beluga whale meat. And of course, in parts of the world where famine and war are rife, people subsist on anything they can get their hands on. We can, in fact, live on an incredibly vast variety of foods, as long as they contain a certain amount of crucial components.

A bewildering array of plant foods needs a commonsense approach (photo at Crafers Garden Centre)

I’ve always been struck by the similarities between our approach in the west to feeding our plants, and feeding ourselves. Faced by a wall of manures (animal, green), composts, soil conditioners, trace elements, rock dusts, organic and chemical, liquid, foliar, pelletised, slow release, fast-acting, specific &/or complete fertilisers, any new gardener will likely be as bewildered as a traditional Inuit transported to the vegetable aisle of an Aussie supermarket! But, in my opinion, basic commonsense principles apply to feeding our plants, just as they do to feeding ourselves. These commonsense principles underpin healthy plant growth.

But how do all those different products fit within the overall diet? And how do they fit within your gardening philosophy? Here’s Part 1: Helen’s Healthy Dietary Advice… to Plants!

Healthy lifestyle

A healthy diet is worth nothing if you have an unhealthy lifestyle, so no point languishing in some dark stuffy corner without plenty of fresh air and sunshine. Humans end up like Norm, but you’ll end up like one of those B-grade starlets in New Idea, all skinny and pale and etiolated. And you can forget about sex in the dark: no flowers or fruit for you! You’ll probably get nasty fungal diseases as well, and though your gardener might treat them, really you should have insisted they put you in the right place to begin with. And you should insist on the right water, soil, temperature and pH while you’re at it. Tell your gardener you can’t pull on a jacket or wellies if it’s too cold or wet (of course, if you’re accustomed to cold, wet, heat or whatever, then no problem).

And while we’re at it, you native lot, don’t think you can grow just anywhere in Oz! You might think you’ll be just fine on Adelaide’s limey soils (pH 8.5+) but, take my word, it won’t be long before you go all sick and yellow. Your gardener might give you iron chelates or sulphur to help, but admit it: you really prefer the acid soils where you grew up, don’t you? So when your gardener first picks you up in the plant nursery, ask her to read your label! If you’re lucky, your gardener will also learn about the principles of microclimate that underlie so much of permaculture and sustainable gardening, and will place you in a happy home surrounded by good friends.

Specific chemicals are like a plant’s vitamin pills (photo Crafers Garden Centre)

A healthy diet

Didn’t your mother teach you about a healthy diet? The main food groups of sunshine, fresh air (especially carbon dioxide) and the right kind of soil? Yes, you can have those high calorie liquid fertilisers and concentrated chemicals as a bit of a treat now and then, but you don’t see humans living on bottles of multivitamins, do you? In fact, you shouldn’t need those vitamins at all if your gardener gives you the right diet to begin with, with plenty of bulky well-rotted compost and/or manures.

Bulky manures and composts

You want them well-rotted so they don’t burn your roots. They won’t give you a quick energy boost, but garden doctors all advise that these low GI foods should form the basis of your diet for sparkling flowers, shiny leaves and clear, unblemished stems!

Soil conditioners

These are great if your soil isn’t friable and you should insist your gardener uses them to make your food easier to digest, like yoghurt, fibre and probiotics do for them. Tell them to add clay breakers/ gypsum (to clay); or biochar, seaweed extracts, dolomite, rock dust, bentonite, soil wetters, GoGo Juice, and other soil conditioners so your roots have lots of tasty worm castings and soil microflora and fauna around them, as well as a good balance of air and moisture.

Liquid fertilisers

These are cheap if your gardener mixes them from a powder or concentrated liquid and great for a quick pick-me-up, but you’ll get flabby if you rely on them. Have you seen those humans who eat only fast foods? They’re big all right, but they’re not very healthy and they get sick easily. All kinds of insect pests will love you because you’re so soft, and you’ll collapse on the first hot windy day that comes along. And if you get all lush and green with too much of that high calorie nitrogen, you can forget about sex: no flowers and fruit for you!

Ask your garden centre experts for advice about your plants’ specific requirements (photo at Crafers Garden Centre)

Complete Fertilisers

These are balanced with the right mix of nitrogen, potassium and phosphorous*, and they’re fast-acting. They’re also high in calories and will burn you if you eat them when the soil is dry, so make sure your gardener waters you thoroughly before and after feeding you. And don’t be greedy – more is less! Too much salt is as bad for you as it is for humans! You’ll shrivel up if you get too much, and so will all the worms and soil microfauna and flora. Besides, like all concentrated fertilisers, they should be used to top up your main diet of compost and organic matter, and they’ll be much more effective then too. They’re OK as a sole diet in the short term, but in the long term you’ll be sorry because, without humus, your soil isn’t getting fed as well as you are. And that soil is your dinner table. No dinner table, no food!

Complete Mineral Mix

A great multivitamin pill if you’re in hungry, leached or sandy soil that your gardener hasn’t yet had a chance to improve with lots of organic matter. Otherwise, as for Complete fertilisers above: overdo at your peril!

Slow release balanced fertilisers

These are great if your gardener forgets to feed you regularly, and they won’t burn your roots if used correctly. But they’re quite expensive, and worms aren’t impressed by them. However, they might be excellent for you if you’re growing in a pot, or as a starter supplement when you’re first planted. Native plants, you know you don’t like phosphorous, so make sure your gardener gives you a slow release designed for you, not a general purpose one.

Foliar fertilisers

Another fertiliser that’s great for a quick-pick-me-up, especially if you’re a fast-growing flowering annual… but again, ideally eaten as a supplement to a basis of a well-composted soil. Make sure your gardeners follow the dilution rates, especially if you’re a sensitive plant like a fern, or a baby, and insist they don’t sprinkle you on
a forty degree day or you’ll end up with a bad case of sunburn.

Organic fertilisers

Can be eaten as a base manure and usually built on chook poo – yum, yum! Some are more concentrated than others, and some have extra phosphorous and potassium added to make them more balanced. Worms, soil microflora and fauna love the humus in them. Cow poo is great too, but expensive to buy in bags (better if your gardener has access to cows). There are lots of other poos – horse, goat, sheep, Zoo, and so on, but let your gardener know that you’ll need a balance of potassium to counterbalance all that nitrogen… otherwise no sex, flowers or fruit for you!

Blood and bone

That old classic your grandmother raved about, and it’s still as good as ever (but dearer). Low in potassium, so great if you’re a roots kinda guy, not so good for those of a flowers and fruit persuasion (you’ve guessed it: no sex for you!).

Specific chemicals

Sulphate or muriate of potash, manganese and boron, iron chelates, these are your Vitamin B, C or D pills. Your garden doctors might give you a dose when they notice a specific vitamin deficiency, or when they see you with lots of leaves but no flowers, but that usually happens when your overall diet isn’t ideal. Let’s face it, a Diet Coke isn’t going to help if you exist solely on Kentucky Fried Chicken and chips! Sometimes, though, finicky, fussy or greedy eaters (yes, I’m talking to you, citrus!) might need a bit of special treatment when you go blotchy and yellow. Tell your gardener to be careful, though. You’ve seen those oddly shaped human body builders who have taken too many steroids. Strange things will also happen to you if you have too much of a specific nutrient or trace element, and it’s NOT a good look!

So there you go. A smorgasbord of food for you. All those clichés apply: variety is the spice of life, too much of anything is bad for you. Next time: Diet and (Garden) Religion.

* The N:P:K ratio

Every balanced fertiliser has a ratio of nitrogen (for leaf growth) phosphorous (for root growth) and potassium (for fruit and flower development). The ratio varies, with lower rates for organic fertilisers compared to manufactured ones. And the ratio varies depending on whether the aim is to promote root, leaf or flower development, or for a particular plant group (acid lovers, citrus, grass, natives etc.) Consider the following products (bear in mind that different brands of Blood and Bone, Complete Manure D, Mineral Mix etc may have different formulations, and that companies change their own formulations over time), and why and when you’d choose to eat them. Think about how much of each product you’d need for the same results, but be aware that some of the organic fertilisers have additional benefits not expressed in the NPK ratio. Have your gardeners check labels and ask nursery staff for advice, especially when they are buying specific, granular &/or concentrated take-aways!

Yates Thrive liquid (6.2 : 3 : 10)

Seasol Powerfeed liquid (12:1.4:7)

Manutec Bloom Booster liquid (6.2:14.6:16.8)

Manutec Fruit and Citrus liquid (25.3-6.7-11.1)

Yates Complete Manure D granular (8 : 3.4 : 9.5).

Neutrog Rapid Raiser pelletised (4:3:2)

Dynamic Lifter pelletised (3.7 :2 : 1.8)

Sudden Impact for Roses pelletised(8:3:10)

Scotts Osmocote Plus for Native Gardens slow release(17.9 : 0.8 : 7.3)

Scotts Osmocote Plus for Trees, Shrubs & Citrus slow release(16.6:2:6)

Brunnings Blood and Bone (5:5:0)

Yates Blood and Bone (6:3:2)

Cow Manure (varies greatly) (0.6:0.2:0.5)

Yates Fish Emulsion (9 : 2 : 6)

Yates Sulphate of Potash (0:0:40)

Yates Sulphate of Ammonia (20.5 : 0 : 0)

Seasol – soil conditioner organic (0.1:0.5:2)

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Helen McKerral

About Helen McKerral

Horticultural journalist, photographer, contributor to many garden magazines, and author of 'Gardening on a Shoestring'. Adelaide Hills, South Australia

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