Gardening / Fertilisers… how different are they really?

“I am often asked about the use of chemical fertilisers, particularly the question: ‘Can I use tomato food on my camellias?’ writes gardening columnist CEDRIC BRYANT

PROMOTING fertilisers is big business with colourful pictures of plants on the packet.

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Fertilisers… how different are they really?

You walk into the garden centre or DIY store and think: “I have tomatoes, so I had better buy tomato food, likewise food for my camellias, roses, native plants etcetera.”

The tills are ringing with all the bags of different plant foods you have just bought! But, do you really need all those different ones? I am often asked about the use of chemical fertilisers, particularly the question: “Can I use tomato food on my camellias?”

The essential ingredients of plant food, namely nitrogen (for leaf growth), phosphorus (root growth) and potassium (flowers and fruit) are shown, respectively, on the back of every packet as N, P and K.

A look at the comparisons of one popular fertiliser brand reveals there isn’t much difference.

PlantsNPK

Complete     7.6    1.0    6.5

Veggie          8.0    1.6   6.6

Rose            7.5    1.5    6.7

Azalea         8.0    1.5    6.5

If you have a surplus of one fertiliser, and before it all goes solid in the bag, use it on other plants. Alternatively, tip all the different fertilisers into a big plastic garbage bin and mix all together.

The only exception is to ensure the plant food for Australian plants is low in Phosphorus (P). Apply fertilisers, like all things, in moderation and always keep back from the stems or trunks. In any case, I still recommend using certified organic plant foods rather than chemical foods for environmental reasons. Don’t start the spring fertilising program before the end of August to early September.

 

THE use of Latin names for plants is still questioned in this day and age, but using their common names often just doesn’t work.

The Latin name provides a great deal of information about the plant, for example Daphne aureo-marginata describes the leaves as with a golden edge.

Latin and common name...  Malus floribunda aka “Japanese Crabapple”

Latin and common name…  Malus floribunda aka “Japanese Crabapple”

Here’s a classic example of the misunderstandings that arise from just using the common name. When we owned a nursery in Yass, a customer asked for “Snow in Summer”.

“Certainly,” I said and showed her Cerastium tomentosum, a low-spreading ground cover.

“It is quite obvious you do not know your plants,” she retorted. “‘Snow in Summer’ is a tall shrub or small tree and that is what I am looking for.”

“Absolutely correct,” I replied, “have a look on the label, Melaleuca linariifolia is also called ‘Snow in Summer’.”

The lesson is that if the lady had used the correct Latin name we could have immediately given her the plant she wanted.

Also, it’s often useless using part of the Latin name, such as Prunus, which can apply to many varieties of trees.

Fleming’s Nursery catalogue lists 50 trees with the Latin name Prunus. Were you to order Prunus at the garden centre, they would ask: “Do you mean Prunus mume, flowering apricot or Prunus cerasus, the sour cherry or Prunus persica can be both a fruiting and a flowering peach”.

It is always preferable to use a combination of Latin and common English names if you are looking for a particular plant. As an example Prunus cerasifera “Oakville Crimson Spire”. This may avoid confusion for you ending up with the wrong plant.

 

DAVID Kennedy, from Clover Hill Rare Plants, Katoomba is the guest speaker at the Horticultural Society of Canberra’s meeting at the Wesley Uniting Church Centre, National Circuit, Forrest, 7.30pm, on Monday, July 21. A selection of his rare bulbs and perennials will be discussed with plants for sale. All welcome, no charge and supper provided.

 

Jottings

• Dig organic matter into the veggie garden in readiness for spring. Pulverised cow manure is excellent.

• With regular rain, bulbs will not need any additional watering.

• Sand and treat with linseed oil all wooden handles on garden tools.

• Cut back salvias to ground level and divide for extra plants.

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