Before you begin, it's worth knowing a few things, including:
- The pH of your soil.
- How well your soil holds water.
- How much sun you get in a given spot in your garden.
These things are pretty important because they affect what plants will actually grow in the spot you're considering.
pH is a scale that measures acidity or alkalinity. The scale goes from 1 (most acidic) to 14 (most alkaline), with 7 as neutral. The closer to either end of the scale, the more corrosive the substance is. Stomach acid is between 2-3, oven cleaner is between 13-14.
Different plants like to have different soil pH's. The technical reason for this is because each plant requires a different suite of nutrients, and those nutrients are easier or more difficult for a plant to absorb depending on the pH of the soil.
Acidic soils are more common than alkaline soils, and easier to deal with too.
You can pick up a DIY pH testing kit at most nurseries. I use one by Manutec:
You can find out what pH most plants prefer by doing a quick web search: put in the name of the plant, and the words “soil” and “pH” and you should find out. As a quick guide, azaleas, rhododendrons and natives prefer acidic soil, and peonies prefer alkaline soils. The best resource I’ve found for explaining the detail is here:
To improve acidic soil, add dolomite lime (but not too much—if you have super-acidic soil you’re better off using hydrated lime or agricultural lime). Overuse of dolomite lime will screw with the proportions of nutrients in your soils.
To improve alkaline soil, the best bet is to buy elemental sulphur and spread that out/dig it in, then water it in. Very small proportions of the sulphur will dissolve in the water and form weak sulphuric acid.
As a guide, if you grab some dry soil and put some vinegar on it, and see bubbles, you have too much free lime in the soil to ever make it acidic.
If you read the back of the tags on the plants you buy, you’ll probably see “well drained soil” as a requirement. Soils are usually a mixture of various proportions of clay, sand, silt and organic matter. Too much clay, the soil won’t drain well. Too much sand, it’ll drain too fast. There’s a test you can do to see how well-draining your soil is, but please, do comply with whatever water restrictions are in your area while you do it.
To find out what your soil is like, dig a hole around a foot/30cm deep and a foot/30cm wide. Get a hose and put water in the hole. At first, the water will probably just disappear. You should be able to fill it up; once the water has drained completely the first time, immediately fill the hole again. If there’s water still in the hole after an hour, you probably need to add something to the soil to improve the drainage. If the water literally disappears before your eyes, you probably have sandy soil.
One tip—don’t add sand to clay soils. Instead of improving the soil, you’ll just end up with something approaching concrete. Unpleasant.
To fix either soil type, add organic matter—compost is better than manure to be safe, as manure can have other unintended effects on your plants/soil.
One product I’ve found that is useful in solving drainage problems is this one:
It’s great, but has of late become hard to find. Last place I found it was Bunnings. It comes in pellet form, so just take the stuff out and dig it into the top layers of your soil, water it in and let nature do the rest.
An alternative when you have clay soils is to build up your garden beds by piling good quality soil up on top of your clay soil to a depth of 8-10”/20-25cm.
This one is fairly simple. Take note of how much sun you get in different parts of your garden, and check the tag of plants you want to plant to see whereabouts in your garden might be a suitable spot. Many rainforest plants, despite being tropical, need lots of shade because they’re used to growing beneath a solid canopy. On the other hand, full afternoon sun can burn native plants. I usually err towards less sun than more, after painful and expensive experiences.
Plants that don’t get enough sun usually turn out “leggy”—long branches with few leaves as the stems quest for sunlight.
So, if you’ve checked all the above, what can you do next?
Plant your plants!
I usually use the following whenever planting anything:
- Water crystals.
- A slow release fertiliser appropriate to what I’m planting.
- A potting/planting mix appropriate to what I’m planting.
- Agricultural drainage pipe.
- Granular soil wetter.
- Seaweed concentrate fertiliser.
I usually also have the following items/tools:
- A wheelbarrow. (Open space will do if you don’t have a wheelbarrow.)
- A decent shovel for digging. I’m 6’3” tall, so I prefer a long-handled plumber’s type shovel with a pointed end, but you choose whatever you feel comfortable with.
- A short-handled shovel for mixing.
- Mini-shovel for delicate work.
Everything below also applies to planting a bed full of seedlings rather than individual plants; you’ll just need to spread your stuff across the whole bed instead of attending to each hole in the ground separately.
I also garden in a similar fashion to the way I cook; paying attention only to the list of ingredients and then making the rest up as I go along. If you want to, you can make precise measurements based on information found on most of the packets of items I’ve mentioned above.
Also, please be aware that any time you’re playing with dirt you’re working around living organisms; bacteria, fungi etc. If in doubt, wear a mask over your mouth and nose to prevent any of it getting into your respiratory tract, where it will cheerfully multiply and cause an awful lot of problems. Safety first.
One last note: if you’ve had proper topsoil trucked in, you probably don’t need to mix potting mix into the soil. However, you should also be aware that mushroom compost is not a good thing to plant acid-loving plants or natives in; it is too alkaline for azaleas and has too much phosphorous for the many phosphorous-sensitive native plants. If you’re going to plant acid-loving or phosphorous-sensitive plants, use a general-purpose soil mix instead.
Dig a hole that’s around 4”/10cm deeper than the pot, and around twice as wide. The wider it is, the easier it’ll be for the plant’s roots to go sideways later. Any plant that requires its roots to go directly downwards probably has a tap root system and will be fine on its own. Pile the dirt you pull out of the hole into your wheelbarrow, or somewhere convenient.
Combine a couple of handfuls of soil, a handful of slow release fertiliser and a generous handful of water crystals in the bottom of the hole. If you have real drainage problems or a plant whose tag explains that it really really hates being wet, you might also want to pile some gravel in the bottom of the hole to ensure free drainage.
Cut a length of agricultural pipe long enough to poke out of the ground at the front of the hole and then wrap around the far side of the bottom of the hole, so it spirals into the hole and ends up at the bottom. This can be used to deliver water directly to the plant’s root system. You’ll probably see this sort of pipe installed where your council has planted trees recently.
Take a look at your bag of potting mix. Compare the size of the bag to the amount of dirt you’ve dug up. If the amounts aren’t roughly equal, dig more holes (or just scrape some dirt up off the surface). Once you have a roughly similar amount of dirt to potting mix, open up the bag and tip the whole lot right on top of the soil you’ve dug up. Mix well.
By doing this, you’re providing a more friable/open medium for the plant’s roots to dig into, and with most potting mixes you’re providing built-in nutrients. Sounds like a pretty good deal to me.
Mix in a couple of handfuls of slow-release fertiliser and a couple of handfuls of water crystals while you’re at it.
Take the plant out of its pot. Don’t do what I did the other day and drop the plant, breaking many of its branches—if you need another person to pull while you hold the pot then go ahead and do so.
Once you have the plant out of its pot, check its roots. If you see them all bunched up closely around the perimeter of the pot, the plant is pot-bound and you’ll need to tease the roots out. Otherwise, you’re all good.
If you need to tease the roots out, the way I’ve found is best is to set the plant in the hole, grab a hose and soak the rootball (to free up the soil a bit; and with the plant in the hole you’re not wasting the water) and then pick the plant up and just go to town with your fingers, pulling at the roots. You’ll inevitably tear some, but if the plant is healthy to begin with then it should recover just fine.
Put the plant back in the hole and turn it around so it’s facing whatever way you want it to. If you have someone like my father-in-law coming around, you may want to break out a spirit level at this point.
Gently tip handfuls/shovelfuls of the combined dirt/potting mix back into the hole. Try to cover what was formerly the top of the plant’s soil level in the pot by a centimetre or two. Pat it down (don’t squash it too much) and then water it in.
This is probably the most important part of the process. If you don’t water the plant in well enough, it will both be in shock from having its roots played with, and there will be air bubbles in the soil that allow fungi and other diseases to form on the plant’s roots. The soil level should fall a bit with proper watering in; that shows the air bubbles are being compressed out of the soil.
Scatter some granular soil wetter around the plant out to the drip line (as far as the branches extend). Water the soil wetter in (just enough to soak the top of the soil well, not as much as when you first planted the plant).
If you want to, you can put some more slow-release fertiliser around the plant at this point, but you’ll have a fair bit already in the soil. The same goes for water crystals—they only work well when the plant’s roots grow through them; being on the surface doesn’t do the plant much good.
The next thing to do is spread our your mulch. Pebbles will look good, keep the plant’s roots cool, and hold their colour well, but won’t add to the nutrients of the soil. Decent size wood chips (e.g. red gum chips) will need to be fairly deep to be useful in deterring weeds. Small size wood chips will do a really good job, but be aware that the coloured ones (e.g. red, black) will fade over time and look really ******* after a couple of months in the sun, and require fairly regular top-dressing. Grass clippings are a good idea, but may be unavailable to you and can turn slimy if they’re not well aerated. Pea straw does a better job than sugar cane mulch of adding nutrients to the soil, but sugar cane mulch does a better job of making the soil more friable (in my experience). It’s up to you what you want to use, but I’d use something more towards the end of that list if you’re planting vegetables. You don’t really want pebble mulch in your vegie patch.
To be really useful, your mulch will need to be around 4”/10cm deep, at least. Most of our mulch is red gum chips, and out the back we get many weeds poking through our 5cm deep mulch, but out the front where it’s 20cm deep (because I dug the bed especially to account for it) we haven’t had a single one in three years.
You will have to water in any organic mulch; it both keeps the mulch together and prevents any dust etc from flying through the air and getting up your nose. Just enough to make sure the water has penetrated to the soil layer will be fine.
Mix up your seaweed fertiliser in a watering can. As a guide, for small plants I usually use about 1/3 of a watering can per plant. For bigger ones, I use anywhere from 1/2 to the whole 10L can per plant. With all the watering you’ve been doing, that will be enough for the plant to establish itself.
That should be about it! Keep checking on your plant(s) over the next few days. If they’re looking poorly, try to figure out why. They could be too dry, too wet, or simply still in shock. If after a week they haven’t recovered to what they looked like in the pot, it’s time to search for answers.
If I get the chance in the next couple of weeks, I'll supplement this guide with some photos.
Hope that helps, if you have any questions fire away!