In nature, desert roses’ needs are minimal as they have grown to co-exist perfectly with the soil and climate of the region they are from. The soils offer them every nutrient they require. Growing them in the home garden environment is totally different to that which they have originated from.
It is the hard work of many people studying the species, propagating, and experimenting to select the better varieties for horticultural production that we need to thank. It is these people who have brought to the table a very unique ‘garden plant’ that many of us admire. If we were, for example, to take a plant from our garden and place it back in the wild, it would most likely not grow.
The many, many years of select breeding has made it much easier for us (the home gardener) to grow, as they are now better suited to commercial production and they can be grown successfully in a wider range of climates. So although they are still Adenium, the varieties that are available to us differ from those found in their native land. We have some varieties with huge flowers, several layers of petals, and in colours that you would never see growing in the wild.
Having said that, a far better understanding of their requirements also makes propagation and growing easier too.
Fertilising
Adeniums do well with a moderate amount of fertilising— much less than would normally be used for, say, veggies or fruit trees—but they still like a feed. I prefer to use organic simply because I am familiar with it and have used it for many years. I have listed as many types of fertiliser as I can think of that are readily available.
Desert roses aren’t the fastest growing plants and it is very tempting to heavily fertilise them to speed up the growth. Please don’t! Too much fertiliser, and particularly a high-nitrogen fertiliser, can produce weak, lanky plants that are more susceptible to pests and disease, not to mention that it is a waste of money as most of the fertiliser will not be used by the plant and instead simply leeched out during watering. Let these plants grow a little slower; it will produce a much finer specimen in the end.
Typically, you can expect a seedling to grow (from seed) and flower for the first time anywhere between 9 months and 3+ years (less widely grown species can take 8 years). The genetic background, species, and growing conditions will be the determining factors of time of flowering.
Gardening Teaches You Patience
This is something I have to remind myself of regularly!
The fact that desert roses are more often grown in pots and a very free-draining potting mix means nutrients can leech out quickly, particularly over the wet season. So for maximum growth and flower results, fertilise a little more often but at a more diluted rate, and only when they are growing. Never fertilise throughout the cooler months when they are in dormancy.
What fertiliser is best? I use and recommend organic, simply because I am familiar using it and it gives me the results I want. What you use will be a decision you need to make depending on what you already have, can obtain, or feel comfortable using. Experiment a little … try a few different types to see which gives you the best results.
“A little is good, more is not always better.”
Chemical Fertiliser
These fertilisers are formulated to provide fast and/or sustained growth to a wide number of crops and garden plants. They come in a few different forms to suit the crop/intended use, e.g. granules, liquid concentrate, controlled release, etc. The three main ingredients of nitrogen, phosphorus, and potassium (N.P.K) are nutrients required by all plants. However, chemical fertilisers are manufactured chemically at a particular ratio for plants that require much more nitrogen than Adeniums need. Some formulas have added micronutrients (other essential elements needed for growth). Use with extreme care. Chemical fertilisers can very easily burn desert roses because of the high nitrogen content. I recommend you to use this type of fertiliser at 25 % of that recommended on the packaging.
Chemical and Organic Blends
There are some types of fertilisers that are organic-based but have small amounts of chemical fertiliser added. These are used for many areas of horticulture. As this type of fertiliser contains chemical fertiliser, care needs to be taken as to how much is used. This will need to be an experiment as each brand and blend is different.
Liquid Organic
This type of fertiliser is fairly easy to use. It can be mixed up in a bucket or watering can and applied around the top of the pot. Use at half the recommended rate for pot plants in 140mm pot size upwards, and dilute a further 50% for smaller seedlings. The range includes fish emulsion, seaweed and/or kelp, liquid blood and bone, or a combination of these. This type of fertiliser is better watered around the root zone than sprayed on foliage. Do not apply in the heat of the day.
Pelletised Organic
This is also easy to use. Use sparingly and remember to keep away from direct contact with the trunk. Pelletised organic fertiliser is usually available as a chook or cow manure base. Some products may include blood and bone as well.
Powdered Organic
This is simply an organic fertiliser that hasn’t been processed into pellets. It is composted and aged and still a very good and easy-to-use option, but again, use sparingly and keep away from direct contact with the trunk. Available in chook, cow, and blends of manures.
Potash
This is one of the three main nutrients required in larger amounts (the ‘K’ in N.P.K). Potash is available either as granules or liquid, and is used to help promote healthy growth with plenty of flowers. I have found the liquid much easier to use. The granules need dissolving in water before application. Do not apply in the heat of the day.
Trace Elements
Some minerals are only required in small amounts but are still essential for all plants. They are called “trace elements” because of the extremely small amount needed. Usually sold as a granular product to be diluted before application. Read directions before use. Do not apply in the heat of the day.
Manure Tea
This is what our parents/grandparents used before bagged manures were readily available. It is a simple idea where you use a manure, submerge it in water in a container, e.g. a 44-gallon drum (for at least a week), and scoop off the liquid to use as a liquid fertiliser. Sheep, cow, goat, horse, or a mixture of these manure types were used. The biggest advantage was that the manure was readily available, and submerging it in water rotted any weed seeds that may have been present. It was also extremely cheap. The only downside to manure tea is that mosquitoes can breed in the water, and that it attracts flies.
Worm Pee
A wonderful, readily available fertiliser for those who have a worm farm and have this on tap. We use undiluted, but you can dilute it.
Blood and Bone
This is available as either powder or liquid. It really stinks and I’m not sure if the plants grow well because of the nutrients supplied or to escape the smell … either way, they love it! Be aware that animals like it too—some may dig around the plant looking for something that has died. The liquid doesn’t smell for long after application, so if you have animals, this may be the better option.
Potting Mix
This is another area of gardening where there are too many choices and for someone that knows very little, it can be very daunting. I would strongly suggest to speak to whomever you acquired your desert rose plant from and ask them directly what recipe or brand they use. If you purchased it from a local supplier, they will know the local weather conditions and what is/isn’t available in your area and can advise you as to what is obviously working well for them. This is important. Local knowledge is invaluable.
Free-Draining
The best advice I can share with you is, regardless of what type, recipe, or brand you use or where you live, your potting mix needs to be free-draining. When you achieve a potting mix that provides the right drainage, 90% of any problems with growing desert roses will disappear. That’s right! 90% of any problems that can occur when growing desert roses are simply erased by using the correct potting medium and providing proper drainage.
It will be difficult to simply walk into a nursery or garden centre and buy an already specially blended potting mix for your desert rose off the shelf. What works for someone on the east coast near Brisbane will not work for someone inland from Townsville. The climates vary greatly and the potting mix will behave differently too. Simply remember the key: it needs to be free-draining! You can easily add materials to a standard bagged potting mix to help increase drainage.
disease-free roots
Both of these potted plants show clean, disease-free roots; a direct result of using a free-draining potting mix. Note that there are plenty of larger particles within the mix, allowing for small air pockets to arise.
Correct potting mix = healthier plant.
Healthy plant = happy gardener!
When you have happy, healthy plants, it is easy to spot any changes happening, and these can then be addressed immediately.
Unless you are lucky enough to purchase a bagged potting mix that is perfect, you will need to experiment a little with ratios and materials to find the ideal recipe.
Coconut Fibre
Processed coconut husk is sourced from sustainable markets. The husk comprises of fine and course material, which both absorbs and holds moisture. It also has the ability to create small air pockets within a mix, allowing water to travel through it, aiding with drainage. I personally use a blend of both fine and coarse in my mix. It is available in a dehydrated compressed block that expands when water is added. It is very economical and not expensive.
Coarse coconut husk
Peanut Husk
This is another product sourced from a sustainable market. I have used this previously but found the supply limited and not available year-round. The only drawback we found was that in our climate it dried too quickly and became water repellent; yet other growers have used it for years and had no problems. Purchase clean peanut shell; if it has an unpleasant odour or looks mouldy, don’t buy it.
(Left) Coarse woodchip. (Right) Fine woodchip (sieved)
Woodchip
Woodchip can be sourced from sustainable markets. You can buy this easily in bags as needed in a few different grades. Chipped bark for orchids is also ideal.
Other materials worth considering are clinker/pumice (volcanic rock), perlite, or coarse/sieved sand.