How to Grow Caladiums in Australia

What are Caladiums?

Caladium is a wide genus of flowering plants, grown mainly for their foliage colour. There are around fourteen recognised species, but within each there are many unique cultivars. Caladium bicolour is the most widely cultivated, with over 1000 named varieties under its wing.

The tuberous roots of caladiums make them easy to divide and help them to spread through loose fertile soil as ground cover easily, but they are not frost hardy, so any part of Australia with winters below 18°C require gardeners to move caladiums indoors to overwinter.

Caladium’s Natural Habitat

All species in the Caladium genus are native to tropical South America (Colombia, Brazil, Costa Rica, Venezuela, Guyana, Peru, Ecuador and northern parts of Argentina). They have naturalised outside that area in similar climates including India and parts of Africa, and grow well in Australian gardens in the right conditions.

Open forests and river banks are their most common habitat, with managed humidity and regular but draining water. Through dry seasons, Caladiums will naturally go dormant and lose all foliage, but in Australia, that dormancy can be triggered by both drought and cold temperatures depending on where you are.

How to Grow Caladiums in Australia

Caladiums can be grown as houseplants, and in exceptionally dry parts of Australia tend to grow better indoors, with more care given to their moisture levels. However, growing caladiums outdoors in Australia is by far the best way to make the most of their stunning foliage and create swathes of impactful planting.

Grow Caladiums Indoors

Growing caladiums in a pot is relatively simple. Give them moist, but not saturated soil, and make sure the potting mix drains well, while holding some vital moisture so it never dries out completely.

For a single caladium plant, you’ll need a pot that’s at least 20 cm in diameter, and the same depth. Fill the pot with a draining, but slightly moisture-retentive compost mix (I recommend 60% organic compost and 40% vermiculite). 

• Leave enough space for the existing root ball of your calcium, and gently place it in the pot, before gently filling compost around the edge.
• After filling the container, water it really well so water is dripping out of the base of the pot. This will settle the roots into their new home, and let you focus on positioning, rather than watering for the first couple of weeks.
• Find a well-lit spot, ideally with 6-8 hours of indirect light per day. 
• Water indoor caladiums once every two weeks, or whenever the soil surface is starting to dry out.

How to Grow Caladiums Outdoors

Outdoor caladiums are slightly harder to care for, planting is just the same. As with indoor caladiums, which need 20cm of space per plant, you should space each outdoor caladium 20-30cm apart. They will quickly fill the gaps.

Choose a bright spot, with moisture-retentive, but not boggy conditions, and add rich compost or rotted manure to the planting hole. This is more for moisture retention than nutrients, so it’s ok to use spent compost here.

Prepare a hole that is at least twice as wide, and twice as deep as the caladium’s root ball, and gently pull soil and compost back in around the base of the plant so it sits level with the soil. Water it in well to settle the soil rather than firming it by hand.

For the first few weeks after planting, water your caladiums every few days so that it doesn’t dry out, then add a 1-2” layer of mulch (bark mulch is perfect) to help hold in moisture through summer.

Propagating Caladiums

Caladiums grow from tubers, not bulbs, as much of the internet claims. Tubers are similar to bulbs, but are more like energy storage facilities at the centre of the root. Like any plant that grows from tubers, caladiums can be propagated from tubers in autumn, winter and spring, but they are also fairly simple to grow from seed if you find a good supplier.

Below, we’ve got guides on how to grow caladiums, depending on what you’re starting with.

How to Propagate Caladium from Seeds

Some caladium cultivars are expensive as a result of their rarity, so buying a full border’s worth of plants can be heavy on the wallet. However, propagating caladiums from seed is relatively straightforward, and made even easier by late spring conditions in most of Australia.

Dried caladium seeds are fine to use with no preparation, and work just as well as fresh seeds. All they need is light, moisture, and a little bit of time.

• Start by filling a seed tray with sieved garden soil, or mix sieved compost with perlite for similar conditions. 
• Then, sprinkle caladium seeds over the surface of the soil at about 4 cm apart (this isn’t important, but it will make them easier to handle later).
• Do not cover the seeds as they need direct light to germinate.
• Keep the seed tray somewhere warm and bright, and make sure it doesn’t dry out completely.
• To maintain moisture, cover the seed tray with cling film.
• Germination can take as little as two weeks, so keep checking them.
• Once your seedlings have germinated, remove any coverings so they can breathe, and keep the soil moist but not damp.
• When each seedling is 2” tall or more, transplant them gently into individual pots of well-drained soil or compost.
• Store the young plants anywhere bright and warm, and move them away from direct sunlight to reduce stress. After about two months you should have young caladiums that are strong enough for their forever homes, but caring for them in containers for their first year will allow them to develop full tubers, so they are more likely to survive winter chills.

Caladium Propagation from Tubers

Caladiums can be propagated from their tubers, but in a different way than most tuberous plants. They don’t readily sprout from their tubers but are capable of it. 

If you’re lucky, you’ll have several plants in one pot that can easily be split, if not, you’ll need to put in a little more effort.

To propagate caladiums from un-sprouted tubers:

• Start by removing your plants from their containers, and shaking off the soil.
• This is best done in winter or late autumn when they are largely dormant.
• Remove as much as 1/3 of the tubers from the peripheries of the plant (the parent plant will grow happily again next year, and potentially with more vigour as a result)
• Find any ‘eyes’ on the tubers, similar to potatoes, or nodes along stems, that look like they have the potential to sprout, and split the cut tubers into sections that are about 4 cm across as a minimum (bigger is ok).
• Leave these tubers to callous for two days so their cut surfaces begin to heal and reduce the risk of fungal infections.
• Plant each tuber into its own pot, and leave it somewhere warm, in lightly moistened soil until spring. In spring, move each pot out into the light, and water them as soon as you see signs of new shoots.
• Then simply treat them like you would treat any other caladium.

Caladium Care Guide

Caladium care depends on the soil conditions, locations, and maturity of each plant, but there are some things that transcend all of that, and should be observed no matter where you are, or how old your plants are.

Overwintering caladiums

In Australia, there are two scenarios that can trigger dormancy; drought and cold. In nature, caladiums grow in hot, damp, tropical regions, and go dormant when the hot summers stop raining. In Australian gardens, you can prevent that simply by keeping their soil moist through summer.

However, in nature, caladiums rarely live in climates that drop below 15°. So our winters can be challenging. In eastern or northern parts of the country, and some central regions, it’s fine to grow caladium outdoors all year round. In others, it’s worth digging them up and storing the tubers in dry, dark conditions over winter.

If you’ve got caladiums in pots, simply move them into a shed, or into the house for winter, where they can continue to display their gorgeous foliage, without suffering from winter colds.

Fertilising Caladiums

Young caladiums can be shocked by fertilisers, so use them very diluted, and rarely until your plants are properly established. For mature caladiums, any foliage feed or house plant fertiliser will do the trick. Just make sure they aren’t overfed.

I tend to feed my indoor caladiums about once a month, with a soluble feed in water. My outdoor plants rarely get fed as the soil is rich enough, but an annual mulch or granular feed will give plants a boost on poor soils.

Pruning Needs

Caladiums are statement plants, and like any garden statement, they should look their best all year round. So as a rule, I always prune out any damaged, dead, or diseased-looking stem by cutting it right to the base. 

Not only does this improve the look of the plant, but it reduces foliage humidity levels, and prevents the spread of diseases. Do this whenever you notice patches, brown lesions, or damage on a leaf as it won’t recover properly. Do the same with any darkened stems, of old foliage that has begun to die back.

Repotting Caladiums

Caladiums in containers are not particularly fast growing, but like any containerised plant, they will need a refreshed batch of compost every two or three years.

Signs that a caladium needs repotting include yellowing foliage, or dry top growth. Especially if the soil remains moist as this can be a sign of either root rot, or root restriction, preventing the natural uptake of nutrients.

When repotting or replanting caladiums, shake off all the old compost, and replant into completely fresh soil. Pot on to a container no more than 10 cm larger than the old one to prevent boggy conditions around the roots.

Caladium Pests and Diseases to Look Out For

Caladiums are more prone to diseases than pests but, as I’ll explain below, there are still a few common garden pests that can harm your prized foliage.

Insects

Aphids, mealybugs, spider mites, scale insects, and thrips are the only common caladium pests. Like all plants, most of these pests are actually a sign of a healthy plant that’s attracting bugs to eat its abundant chlorophyll. However, if you notice spider mites, the most likely cause is dry soil.

If any pests are significantly affecting your caladiums, amend your watering routine, and spray them off with a powerful spray nozzle on your hosepipe. Refer to our guides below about the pests mentioned above for more info. 

• Aphids
• Spider mites

Mammals

Despite caladiums being incredibly toxic to almost all species of mammals, for some reason they are also incredibly attractive to wild mammals. If you have any herbivorous pests living near you, consider spraying caladiums with garlic, or chilli teas to put them off.

Fusarium root rot

Caused by Fusarium solani, Fusarium root rot is a fungal pathogen that exists in most cultivated soil and affects most fleshy-rooted plants. The fungus thrives in warm moist soil, where moisture doesn’t drain, and is particularly difficult to manage in Caladium planting beds due to the moisture requirements. Providing good drainage to match moisture retention is a must.

Dasheen mosaic virus

Dasheen mosaic virus is particularly prevalent in densely planted areas of caladium and similarly leafed plants, spreading through touch, insect movement, and within infected plants.

As the name suggests, initial signs are mosaic patterned marking across the leaves. To prevent spread, remove affected foliage immediately.

Pythium Crown and Root rot

Pythium spp. is a family of soil borne pathogens, until recently classed as a fungus, but they are in fact parasitic oomycetes (which work in near identical ways, so you’d be forgiven for the misunderstanding).

The symptoms are mushy roots, and mushy crowns or plants, as the root rot is hard to spot until it climbs up the plant to destroy the top growth. Remove any affected plants and attempt to remove any diseases materials.

It is possible to rectify infected plants by harsh pruning, but keep them separate from others until you’re sure.

Rhizoctonia solani

Another root rot that is particularly efficient at damaging caladiums is rhizoctonia. The overall effect is similar to pythium rot, but with one key difference. Rather than creating a wave of mushy rot, it spreads in brown lesions in its early stages, and is often limited to one side of the plant.

Treatment will mean removing the infected section and burning it, and keeping an eye on the rest of the plant for a few weeks while keeping the soil as dry as possible to prevent spread.

Caladium Frequently Asked Questions

Do caladiums come back every year?

Caladiums are long-lived perennials, and will come back year after year. If your plants are beginning to fade, refresh their compost, and split them to reinvigorate the roots and promote fresh new top growth.

Do caladiums like sun or shade?

Caladiums do best in bright, indirect light, where they benefit from high temperatures without too much beating sun to compete with for moisture. The more shade you can provide, the longer their moisture levels will stay stable, and the easier it will be to prevent fungal problems in their relatively damp growing conditions.

How many years do caladiums last?

Caladiums go on producing gorgeous foliage for well decades, without any need to replace your plants. Like any herbaceous tuberous perennial though, it is a good idea to thin out your borders, and split plants occasionally to prevent hollow sections of planting.

Are caladiums high maintenance?

I would say, from personal experience, that caladiums are fairly low maintenance, but definitely higher maintenance than most dramatic foliage you can plant around the house and garden.

Their moisture balancing act is tricky enough, but once you find the right spot, they rarely need ongoing intervention.