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The Top 5 Myths & Mistakes to Avoid Killing Your Indoor Plants

#1 Don’t add a drainage layer

Is this the exact opposite of what your mum taught you? Me too! Even the name is a myth. It doesn’t increase drainage at all! You’d be better calling it a ‘root rot layer’.

Turns out the tradition of adding a drainage layer – typically bark or pebbles - to the bottom of your pot is super smart, provided that pot’s going outdoors. It sounds like such a good thing, but gravity doesn’t agree.

That layer actually helps retain water, creating what’s called a perched water table, where the water gathers and sits above that layer. That lifts water up closer to the roots. Great for pots outside, where containers dry out too fast. But indoors? no thank you! That’s the opposite of what you want.

If you're interested in learning more about the science behind why, here's why never to add a drainage layer >

Instead of adding a ‘drainage layer’ it's better to DIY or buy your plants a free-draining, indoor potting mix. Add that right to the bottom of the pot. That will keep water free-flowing down and out.

I love the Bioleaf potting mix for my jungle but you can DIY your own bl. If you’re worried about losing soil out the drainage holes when you water, just trim some drainage mesh to fit. Job done.

Learn more about why drainage layers do NOT increase drainage >

This is another myth that comes from our outdoor garden buddies. The majority of indoor plants don’t ‘need a rest’ or go dormant in winter like many do outdoors.

In fact, most of our favourite tropical-loving indoor plants come from habitats with a 12 month growing season, where it stays warm and humid all year round. They simply grow faster or slower according to the season, but don’t go dormant.

Subjected to colder temperatures and reduced daylight hours in winter, indoor plants will slow down, but don’t completely stop growing (there are a handful of exceptions like Caladium that die back down to a bulb in winter).

Even when leaf growth slows down or stops, our indoor jungle is busy growing below the surface. Plants shift their energy to their roots over winter. Roots don’t go dormant. In fact, nutrient storage increases over winter.

Think of it like your plant putting itself on charge after running their batteries low powering rapid growth in Spring and Summer. Plants replenish, then increase their nutrient stores in winter, building up nutrients and conserving energy, ready to power the next growing season.

Plants also play the long game. If you starve your plants over winter, most nutrient deficiencies won’t make themselves known right away. Come spring is when those deficiencies can cause smaller, slower growth, or in the case of less mobile nutrients, even deformed new growth, or leaves and buds that soon brown and die early.

Instead, try the ‘weakly weekly’ method. Do feed throughout the year, but less in winter.

Here's what's really going on in winter > and what the Weakly Weekly Method is all about > 

Have you even been given the advice to just cut off yellowing leaves? That it’s ‘just an old leaf’? Totally normal and nothing to worry about? I’ve also been told you should cut them off because they ‘use up the plants energy’.

In fact, it’s entirely the other way around! Those yellowing leaves are your plant’s life support system right now. If you do cut them off, without fixing the reason why, your plant will take another leaf, and another, until you either find and fix the cause, or it eventually runs out of life support leaves and dies :(

There are 5 common reasons why your plant's going yellow, here's what's wrong and how to fix it > 

Unlike nitrogen and other mobile nutrients, calcium is an immobile nutrient. That means when your plant is deficient in calcium, it can’t just take it from another leaf.

Calcium is an essential macronutrient, meaning plants need high levels of calcium. Yet it’s the other macros – nitrogen, phosphorus and potassium – that normally get all the attention.

It’s a common mistake to think because you fertilise, you can’t have a calcium deficiency, however if you check the label you’ll find a good 99% of fertilisers do not include calcium.

That’s also why there are lots of ‘hacks’ online for how to increase calcium for indoor plants. Eggshells, milk water, dolomite lime, gypsum, yoghurt, molasses and more. Before we look at how to fix a deficiency, let’s check the signs.

• stunted, smaller leaves
• weaker stems
• tip dieback on leaves
• deformed leaves
• cracked or split leaves or fruit
• leaves that ‘cup’ or curl
• buds that form but die before flowering or fruiting (I've had this happen in both my orchids and my hoyas)

The bad news is you can’t correct a calcium deficiency in that stem, leaf or bud, as the calcium was required back when it was forming. A deficiency when growing, is a deficiency for the life of that part of your plant. The good news is you can correct it for the future, so it doesn’t harm new growth.

Milk water, yoghurt and molasses can end up smelling and attracting pests (unless you water it down so much that it doesn’t provide enough calcium!).

Dolomite lime is an excellent way to quickly increase calcium, but can also change the soil pH (which can be a good or a bad thing). Take care to follow the directions. If you can, test your soil pH before and after. Dolomite lime needs reapplying every 3 months / once a season. Here’s how to apply dolomite lime and how much to use for indoor plants.

Eggshells are quite honestly a waste of time. In a compost heap outside they have been shown to take years to break down. And that’s in ideal conditions! For our indoor plants, even with drying out and smashing the shells down into a fine powder, they may not break down at all. If they do, your plants may not benefit for a very long time.

My own method when rehabbing a plant in trouble is to start with a single application of dolomite lime for an instant boost (I use the Yates Dolomite Lime), then continue with a complete and balanced fertiliser. Sounds simple - and yes, you can skip the dolomite lime step - but you’d be surprised how few fertilisers actually include calcium!

If you prefer an all-in-one solution, find yourself a fertiliser that already includes calcium. There are a handful that include calcium, including GT Foliage Focus and Dyna-Gro Foliage Pro.

If you’ve added calcium but are still seeing signs of a deficiency, there might be something blocking your plant getting the calcium you’re giving it. Just dumping more calcium on isn’t going to help if this essential nutrient can’t get to where it needs to be.

Calcium travels around your plant with water, so you want to avoid underwatering. A soil pH around 6 is best both for calcium absorption and all the major nutrients, so best to raise or lower your soil pH first if needed or that extra calcium will go to waste.

Cold temperatures also reduce calcium uptake. Consider a heat pad over winter if your place gets below about 15 degrees on the regular. Although many of our favourite tropical indoor plants prefer high humidity, that needs to come with good airflow, otherwise the combo of high humidity and stagnant air can also reduce calcium getting where it’s needed.

I’ve heard ‘plants like being rootbound’ said so often that it feels like it has to be a fact, right? Not at all! Of course plants don’t like being rootbound. Plants outdoors don't have compact little root balls only growing directly underneath them. So why do we do this to them indoors? To save plants from us!

Kept in ‘too big’ a pot the chance of root rot goes WAY up. Lots more substrate means lots more capacity to hold water. Root rot can be a death-sentence. A smaller pot reduces the chances of root rot, protecting plants from over-watering. Under-watering and less substrate is so much safer. Water again too soon, or keep the substrate too moist, and that smaller pot could be a life saver.

Another benefit (for us) is forced reproduction. In response to the stress of being rootbound, plants can divert their energy from growing roots and leaves to survival mode. For some that means flowers, for other’s pups. Flowers make US happy and it’s easy to think flowers mean a happy plant, but they might be super stressed and responding to conditions that tell them they’re going to die.

Limiting space for roots limits growth. Want a bigger plant? Don’t be scared to pot up. BUT - and this is biggie - be extra careful about what you pot into.

The bigger the pot, the more important a free-draining, airy substrate becomes. Typical indoor potting mix holds too much moisture for too long, drowning roots. Buy or DIY a substrate that holds little to no water to make a larger pot safer. I love the Bioleaf potting mix.

You’ll often see advice to pot up 1 to 2 sizes only. For example, from a 14cm wide pot to a 16cm wide pot. Another benefit of not potting up too big is leaf growth. When you jump up too much in pot size, a plant can appear to ‘stop growing’. That’s normal. And it is still growing, but not where you can see it.

Once they recover from repotting, plants given much more room than before will shift growth to below-ground instead. They get busy sending roots out to explore all that new space first, instead of growing leaves. If you do upsize too big too soon, you may have a long time to wait before your plants diverts its energy from the roots back to stems and leaves.

Two other considerations are looks and space. With a jungle my size, huge pots restrict how many plants I can fit. See? All about me again ;) Plus I admit some plants look plain silly in a pot that’s ‘too big’.

If it is time to repot, here's what to do BEFORE you repot >

Well there I go again. In my usual fashion I’ve gone a written a short novel! I do hope you learned something new and can avoid some of the common mistakes I made when starting my plant parent journey. I love sharing what I’ve learned, including admitting to the mistakes I’ve made, and the myths I also used to believe in!

If you want to continue your learning, there are more free plant care guides waiting for you on my blog, and lots of plant care tips on my Instagram too :)

Anna @lovethatleaf