Ask Erik - Improving Rooted Cuttings
Hello Erik,
I take cuttings from mother plants and root them in plug trays. The plugs are compost/polymer and I keep them covered with humidity domes until roots are coming out of most of the plugs. Usually the cuttings are rooted in about 14 days, with about 90 percent of them looking good enough to transplant into rockwool cubes for the vegetative area. Do you have any tips for improving this process?
Because my garden is maintained in various stages of growth for perpetual harvests, I want to be able to get more cuttings every 10 days or so from the mother plants I have. The mother plants are kept in a separate area with separate environmental controls. I am already maxed out as far as space goes, so I don’t want to increase the size of the area for mother plants. Do you have any advice for increasing the output of my mother plants? They are only one cut away from the original seed mother, and I prefer to keep these specimens, as opposed to taking clones from clones to make more mother plants.
Thanks.
Your timeline for rooting cuttings is near average, as is your rate of success. Different varieties of plants will have different rates of time required for rooting. As a matter of fact these rates will even vary from strain to strain within the same plant variety. Often some of the highest-valued varieties can be the most difficult to propagate; some people might surmise that they are genetically programmed (and therefore selected) for their output in certain areas, rather than being “all-rounders,” which would include ease of propagation.
Pre-fabricated aeroponic cloning systems can improve how quickly your cuttings root, and tend to produce healthier and more vigorous cuttings compared to conventional rooting methods. In addition, you can root much larger cuttings in aeroponic rooting systems with greater rates of success.
For example, using aeroponic cloning methods you can root cuttings that are 6–9 in. in height with several nodes and sets of leaves; this will often translate into less time required in the vegetative growth phase to reach the desired height before initiating the bloom phase. Aeroponic cloning systems will usually root cuttings about 25 percent faster than with conventional propagation methods. This faster rooting time is often associated with the higher DO (dissolved oxygen) and ambient oxygen levels available in aeroponic systems compared to conventional growing methods and growing medias. Oxygen is the secret ingredient to faster rooting times.
With any rooting method or growing medium there are some formulations available that will help maintain the health and vigor of your cuttings during the rooting process and may help to promote faster and better root development. Products containing a full spectrum of B-vitamins such as B-1, B-2 (riboflavin), B-3 (niacin), and B-7 (biotin), not just thiamine hydrochloride (B-1), will help reduce the amount of stress the cut material is undergoing during the rooting process. Less stress translates into faster rooting times.
Additions of premium-quality fulvic and humic acids will help improve the overall health and vigor while assisting in nutrient absorption and transport in the cuttings. Fulvic acid and full-spectrum B-vitamins can also be applied as a foliar spray occasionally during the rooting process, and can be used in the reservoir for aeroponic rooting systems. Studies have demonstrated that cuttings with higher carbohydrate contents are quicker to root. Growers may supplement carbohydrate levels in conventional rooting medias for quicker rooting.
Also for faster and stronger rooting rates, growers should load their mother or donor plants with carbohydrates. There are products available that are formulated to mirror the plant’s natural carbohydrate profile and should be applied to keep carbohydrate reserves in the plant at a maximum, which becomes critical when donor material is frequently removed from the plant for propagation purposes.
Fulvic acid and B-vitamins that are essential to the health and rate of rooting in cut material should also be present in the donor plants before cuttings are taken. This makes applications of Fulvic acid and B-vitamins equally important to mother plants. In this sense the material to be removed from donor plants for the rooting process is “primed” before it is removed. From there it is a matter of maintaining these levels through the rooting process rather than attempting to introduce these beneficial substances to non-rooted material, where the capacity for absorption is limited.
To stimulate a higher rate of shoot production in mother plants, where longer internodal distances are desirable, there are specialty foliar sprays that will do exactly this. For very high output in mother plants, begin to apply these sprays at a concentration of 450 ppm and gradually increase levels up to 1200 ppm (as plants gain stature). While doing so, nutrient levels applied to the root zone should be reduced as foliar concentrations increase.
With separate environmental controls you can also stimulate a higher rate of shoot production. By maintaining slightly higher humidity levels in the mother room (i.e., 75 percent) you can increase internodal distances, thereby increasing the amount of material available for cuttings to be rooted.
Carbon dioxide (CO2) levels can also be elevated (i.e., to 1500 ppm) to increase growth rates by as much as 35 per cent.
Growing mother plants in a medium-based hydroponic system such as recirculating buckets will provide higher levels of growth-increasing root oxygen while still buffering against potential problems due to the large amount of growing medium and nutrients surrounding the roots. In fact, a mother plant grown in the same-sized container filled with grow rocks and/or coco coir will be capable of producing a much larger and more vigorous mother plant versus a soil/soilless growing media following conventional cultivation practices.
Always ensure that donor material is free of insects and or diseases before taking cuttings. There is little sense in transferring problems from an existing crop into a future crop. Starting crops with the healthiest cuttings available helps growers ensure maximum yields at harvest.
Cheers,
Erik Biksa