Rooting hormone helps some plant cuttings grow new roots but it is not recommended for all plants. Find out when—or if—to use it when growing new plants from cuttings.
5 Essential Plant Propagation Methods to Grow Everything gives a good overview of different propagation methods.
Rooting Plant Cuttings with Rooting Hormone
Should I use rooting hormone?
Rooting hormone is not always beneficial or recommended.
- Tender, fast-growing plants including softwood cuttings do not need or benefit from rooting hormone.
- Tougher, slower-growing plants including hardwood cuttings can benefit from rooting hormone.
Synthetic rooting hormones (gel, powder, or liquid) need one of these to be effective:
- IBA – Indolebuyric acid (synthetic auxin) or NAA – Naphthalene acetic acid
- Gel form is often most effective
Rooting Hormone Gel | Amazon
Naturally-occurring rooting hormones
- Auxin (IAA – Indole-3-acetic acid) – found in willow (Salix spp.)
- Folklore (do not contain auxin): aloe vera gel, aspirin, cinnamon, coconut water, honey, seaweed extract
- Plant Cuttings & Hormones
- Rooting Hormone Plant Lists
- How to Apply Rooting Hormone
- Natural Alternatives to Synthetic Rooting Hormone
Plant Cuttings & Hormones
When you take a plant cutting to grow a new plant, it’s a race against time.
That piece of plant has been cut off from its life source.
To survive, either the natural rooting hormones (auxins) inherent in the plant are going to kick in or we can assist them.
In general, faster growing plants and young cuttings do fine on their own without adding rooting hormone.
Slow-growing plants and woodier cuttings may benefit from the application of rooting hormone. This quickens root growth before rot, disease, or drying out occurs.
I’ve listed plant examples from both groups below.
Why Not Use Rooting Hormone For All Cuttings?
While some gardeners opt to use rooting hormone for everything, it is really not necessary and might be detrimental in some instances.
Proper amounts of rooting hormone on the right cutting do just what we hope: stimulate root growth.
Too much and growth is halted.
If the cutting is known to provide enough hormone on its own, let it be.
If it’s slow growing or woody, the added hormone can help.
Natural vs Synthetic Rooting Hormones
Rooting hormones exist naturally in plants and we can buy synthetic versions as well.
Natural rooting hormone: auxin
• IAA – Indole-3-acetic acid
Synthetic rooting hormones available in commercial products
• IBA – Indolebuyric acid (synthetic auxin)
• NAA – Naphthalene acetic acid
Synthetic rooting hormones are available in gel, powder, and liquid forms. Gel tends to work better than the others.
Rooting Hormone Powder | Amazon
Rooting Hormone Gel | Amazon
What about natural alternatives? I’ve included notes about honey, willow, and more below.
Should I Start Cuttings in Soil, Soil-less Potting Mix, or Water?
You’ve probably noticed cuttings may be rooted in a variety of media including soil or compost from the garden, commercial potting mix, sand, or water.
The best choice depends on the species, the cutting and growing conditions.
Generally, I find slow-growing cuttings are more likely to rot if soaked in water because they need to soak for weeks or months or longer to form roots. For these, I dip the cuttings in rooting hormone and plant in potting mix.
Fast-growers may root quite readily in water (sweet potato vine is a good example). I do find, however, that water roots are not as easy to transition to soil.
Overall I prefer using potting mix or vermiculite for cuttings unless I intend to continue growing the plant in water.
Keep in mind that whatever instructions you follow, there are numerous variables that can affect outcome.
The more we follow optimum cuts, timing, temperature, humidity levels, and so on, for each particular species, the better.
Watch the Video
This video shows how I prepare hardwood cuttings for rooting. There are dozens of plants you can propagate this way. These ones are good candidates for rooting hormone.
Rooting Hormone Plant Lists
As mentioned, with the right cutting at the right time in the right conditions, many plant cuttings will root quite readily either in water or potting mix without the need for rooting hormone.
But, there are some plants that are stubborn.
I gathered this list while reading about rooting hormones: it is not a definitive list but works as a starter guide.
1Use Rooting Hormone
- Hydrangea | See tutorial here
- Lithodora diffusa
- Phlox paniculata
- Phlox subulata
3Use Rooting Hormone
- Phlox drummondii
Lots more annuals show moderate benefits including:
Begonia * Fuchsia * Geranium, Pelargoniums * Lantana * Plumbago * Salvia * Vinca major and more.
How to Apply Rooting Hormone
Read the product label for specific instructions: too much rooting hormone can inhibit growth.
Start with a good cutting (right growth stage and plant section) – your tutorial should give you this info.
- Place a small amount of rooting hormone in a secondary container so you don’t contaminate the source.
- You only need rooting hormone applied to the part of the stem that will be buried.
- Use a dibber to create a hole in the potting mix and insert cutting treated with rooting hormone. Then gently fill in any gaps with potting mix.
Rooting Hormone | Amazon
Natural Alternatives to Synthetic Rooting Hormone
Do They Work?
This is the Wild West of the gardening world. There is a natural remedy for everything!
The problem is, most of the things recommended do not do what’s promised.
For example, honey is often recommended as root stimulant during propagation but it doesn’t contain any hormones that could do this.
It has other interesting qualities but stimulating root growth is not one of them.
Here are some items I have seen suggested as root stimulators.
Each has valuable other uses, but few have ingredients that promote growth:
- Aloe Vera gel
Cinnamon is not a rooting hormone but some gardeners use it to prevent fungal diseases when starting seeds indoors.
- Coconut water
Honey is antiseptic and anti-fungal but it is not a rooting hormone—it’s basically sugar.
- Seaweed extract
There is evidence this can stimulate root growth both in cuttings and transplants. The trouble is finding the right product and application amount.
- Willow water
Willow (Salix spp) does contain the plant hormones salicylic acid and auxin.
But does this mean they are readily available in sufficient amounts in homemade willow water?
We have no way of knowing. Each brew will be different depending on the source materials used and how it’s made.
Lots of gardeners experiment with it, but, without using a consistent formula in proper control studies, there is no way to prove it helps. When you use it for rooting cuttings, how can you know that they wouldn’t have rooted anyways? Success stories are anecdotal at best and my results may differ from yours.
The good news is it is unlikely to cause harm. But, if you want something more reliable, use a commercial rooting hormone product where recommended.
Kitchen Propagation Handbook
7 Fruits & Vegetables To Regrow As Houseplants
by Melissa J. Will
Learn how to grow houseplants from avocado, oranges, lemons, ginger, and more using leftover pits, seeds, and roots.
This ebook is a digital file (PDF format) you save to your device. It is not a physical product.
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And that’s rooting hormone 101. Use it wisely and you’ll have lots of free new plants.
~Melissa the Empress of Dirt ♛