Most people believe that it is difficult to grow roots, especially for a sick orchid that has lost its roots to root rot or overwatering.
To encourage an orchid to grow roots, you only need to provide two conditions: warm temperature and moisture (but not too much) at the base of the stem. Also, a kelp and seaweed extract that is rich in plant hormones can be used to boost root growth.
To learn more about how to do so, read on.
1. Importance of growing roots
While many home growers focus on the flowers and leaves, it is more important to grow as many and healthy roots as possible.
The roots play a crucial role in the overall health of an orchid, not only in stabilizing the plant in a pot or attaching itself to a tree, but also in the absorption of moisture and nutrients. An orchid that has only few roots or even has lost its roots would be set back from spiking as it would prioritize its energy derived from photosynthesis on growing enough roots to support its moisture and nutrient needs.
Roots are also an important health indicator of orchids. If an orchid has not grown new roots in the growing season, it is a sign that the orchid is under stress, such as lack of ventilation around the roots, pests, and fungal attack to the leaves.
2. Orchids grow roots when it’s warm
In nature, most orchids grow new roots every year when it gets warm at the end of winter, spring and summer. If the temperature of the growing environment is too low, you can put a heat mat under the pot to stimulate root growth.
For sympodial orchids (i.e. orchids with rhizomes) such as Cattleya, Dendrobium, Oncidium, etc., new roots appear usually when new growths are maturing. For monopodial orchids (i.e. orchids growing from a central stem) such as Phalaenopsis, Vanda, etc., new roots appear as they grow new leaves.
Some orchid species such as large bifoliate Cattleyas, e.g., Cattleya leopoldii and Cattleya bicolor, grow roots only during certain specific times of the year. They should be repotted when they are about to grow new roots.
3. Orchids grow roots when there’s moisture
Orchids that have lost their roots to rot are mostly due to overwatering or a medium that holds too much water.
The key to growing new roots for a rootless orchid is thus to first correct the watering habit one has previously and maintain a good level (not too much) of moisture around the base of the stem.
This can be done in 3 ways:
- Resting the rootless orchid on new moist media. It can be bark with a top layer of water-retentive media. Sphagnum moss which is highly water retentive would be a good choice for top dressing, especially for dry growing environments. For inorganic media, small pebbles can also be a good choice for top dressing to lock in moisture.
- Suspending it above water close to the water, but not touching the water. This can be done in a narrow glass with water on the bottom.
- Putting it inside a bag with some moist sphagnum moss to create a humid environment. This method is also known as the “sphag and bag” method.
The moisture helps the orchid to grow roots and keep newly emerged root tips from drying out.
Whichever setup you use, the orchid should not be exposed to high light as it focuses its energy on regrowing its roots.
Here is an article to learn more about these 3 setups to save a rootless orchid.
It must be noted that promoting root growth for a healthy orchid can be quite different from that for an orchid that has lost all its roots because there are no roots to absorb any root-promoting product.
4. Kelp/Seaweed extract can boost root growth
For orchids with at least one living root, kelp or seaweed extract can be applied to grow more roots and make them grow faster.
It must be noted that kelp or seaweed is not a fertilizer, but rich in plant hormones, especially auxins and cytokinins, which are naturally produced by plants in their growth. When shoots grow, the buds (growth tips) produce the plant hormone, auxin, which would travel down to the roots to stimulate root growth.
When roots grow, the root tips would subsequently produce cytokinin which would travel up to trigger shoot growth to promote cell division. It is a natural back-and-forth cycle.
When we apply such plant hormones to a plant, it would boost one of the processes and in turn boost the other. This explains why the growth of roots and leaves often happens around the same time.
I recommend the kelp and seaweed extract by Bloom City which is a blend of 7 types of kelp. A 32 oz bottle is diluted up to 180 gallons, so it can last a long time. It is also organic and can also be used in your vegetable garden for other plants.
Here is an in-depth article to learn more about how to use seaweed extract in the watering regime.
5. How long does it take for orchids to grow new roots?
Depending on how stressed an orchid is, it can take between 1 week to a couple of months to grow new roots.
6. What nutrients help root growth
Macronutrients phosphorous and potassium help a plant develop new roots as well as strengthening the old ones. But, you do not need to feed a plant with only these two nutrients. A balanced NPK fertilizer would be ideal for root growth.
To sum up, orchids naturally grow roots every year when it is warm and when there is moisture around the base of the stem. When these two conditions are available, growing roots is not difficult at all.
Although helping a sick orchid grow roots can take between 1 week and up to 3 months, the emergence of new roots is highly rewarding and is also key to the hydration and nutrient uptake of the whole plant.