FAQs on Choosing and Caring for Potted Plants : Part 1

By Iain Eaton

Owner and Horticulturalist (ie. expert garden dude) at Bliss.

DESIGN :

Is there any reason I should go for a tall pot or squat?

If space is a consideration then yes, go for a taller narrow pot.

If the pot and plant are going to be exposed to wind, then a shorter wider pot would be safer. You’ll need one with a wider base touching the ground and a lower center of gravity.

As far as the look, this is up to you. It can be so hard going to the shop to buy your Garden Pot and not having a clue which one will look the best. One idea is to pick a few shapes and colours you like, and then paint and cut out cardboard to emulate the shapes you like. A little effort, but much easier than lugging ceramic pots home and back again when you don’t like them! Some shops will let you buy the smallest version of a pot you like to take home and try the colour out, making it easier to bring them back when you know what you want.

Some plants, such as camellias, have a shallow root system and will be better in a shallow, wide pot.

Do darker pots get hotter in the sun?

Yes. Therefore the moisture in the potting mix will evaporate quicker. Also consider how thick the wall of the pot is. Pots with a glaze or with thicker walls won’t heat the soil as much, therefore less evaporation occurs.

MAINTENANCE/CARE

Do I need to seal my garden pots?

My advice is to seal any pot you buy, be it terracotta, glazed, Fibreclay or fibreglass. This will do a few things.  

• Reduce evaporation and keep your potting mix moist for longer.
• It will also stop salts and lime leaching out of the pot and depositing on the exterior. Yes, I have seen this before. It doesn’t happen all the time, but when it does it can be quite unsightly.  
• If you get frosts, the less water leaching into the wall of the pot the better. If it freezes, depending on the quality of the pot, it may crack.

How often should I water a plant in a Garden Pot?

Unfortunately there is no ideal watering time as there are so many variables. Size of the plant, size of the root ball, the season, direct sun or shade, type of garden pot  (ie glazed/terracotta), size of the pot, type of soil, mulch or no mulch… see what I mean?

The ideal way to know how much water to give a plant in a pot is to give it a good soak and then check the potting mix every day for a few weeks. Do this by digging down at least half way to the bottom of the pot and feel the mix with your hand. The potting Mix must be moist, but not wet. If you let it dry out completely it can be very hard to re-wet, even with Wetting Agent.

If you’re game you can also give your plant a good soak, then wait till it starts to droop. If it takes 3 days then water every 2 days. The problem with this method is that some plants don’t droop, they just die, like conifers.

Watering a newly potted plant

Any newly potted plant must be watered  with the same regularity as it was when it was in its original pot. Of course the roots will spread out into the fresh potting mix in time and as this happens you will not need to water as often.

Do I need pot feet/saucer?

Saucers are obviously good for catching excess water so it doesn’t run out onto your nice deck or paving. However usually they aren’t deep enough to hold excess water for the plant to use. Even if they are, the plant may not always be able to reach it, so don’t rely on this. Also bear in mind that if you expect the saucer to keep the spot under the pot dry, you may be disappointed. They are rarely perfectly water tight, so you will often have a wet patch below the saucer. If you need to keep it dry, don’t put a pot there.

Pot feet are actually better at keeping a spot dry. Yes the excess water will run onto the deck/paving but it will be allowed to dry since the pot is held off the ground.

Do I need to have stones in the base of my pot?

No… but it doesn’t hurt. Potting Mix is designed to drain well. If your pot has adequate drainage holes you don’t need stones in the bottom of the pot.

Can I use soil (dirt) in my pot instead of Potting Mix?

No you shouldn’t. There are a number of reasons, but the main one is water holding capacity/drainage. Garden soils will hold a lot of water. However, when they dry out they will shrink and it is very hard to re-wet them. The water will run straight through the dried out cracks or the down the inside edge of the pot and out the bottom.

Can I use half dirt / half Potting mix?

No, if you want to make it cheaper, use a cheap Potting Mix in the bottom of the pot with the good one at the top. Alternatively if it is a large pot and you want to save on Potting Mix, use old bricks or rocks in the bottom to take up room.

Can I use a cheap Potting Mix?

Yes…. But in my opinion a potting mix must have 2 key ingredients. Slow release fertilizer, and wetting agent. Usually cheap potting mixes won’t have these. Basically a cheap Potting Mix will be composted  bark chips only (hopefully...)

So in short

• You need Wetting Agent, renew every 6-12 months
• Slow release fertilizer, renew every 6-12 months
• If you’ve got an expensive plant, don’t buy a cheap potting mix
• If you’re planting Pansies or Petunias, it doesn’t matter so much

 

What potting mix should I use?

How much do you care for your plant? Is it a keeper, or just annuals? If it is a keeper, ie a lemon, or a standard camellia, choose a quality potting mix. The things to look for are

• Australian standard ticks,
• Good slow release fertilizer, ie osmocote, nutricote
• Trace elements
• Wetting agent

What fertilizer do I use?

The best fertilizer to use in a Garden Pot is a “slow release”. These release fertilizer by osmosis – were you listening in High School science class? Basically it releases as the plant needs it, not harming the plant with an excess of salts burning the roots. These fertilizers will last up to 6 months, unlike normal garden fertilizer which will virtually leach straight through.

For heavy feeding plants, ie Fruit trees, it can be beneficial to use a soluble fertilizer as well as the slow release. These are usually a powder which you mix into water in a watering can.

It doesn’t hurt to add manure, blood and bone, or seasol. But I think the best value of these are as soil conditioners. They add organic matter and nutrient to impoverished soils. 

Stay tuned for Part 2, where I'll go through some suggested plants for pots and what special requirements each may have.