Most growers realize there is more to cultivation than just sticking something in the dirt and letting nature do the rest. Whether we are talking about cuttings, clones, transplants or even just sprouted seeds, all plants need to develop a solid root system. Some plants definitely set and grow roots more easily than others, but they can all use some help. It is incumbent upon any grower that wants their plants to develop strong and healthy to do what they can at this critical stage.
It is vital to make sure that your plants have an environment that is conducive for sprouting and sustaining vigorous roots. They also need the vitamins and nutrients that are essential for these processes. With a little know-how, it is not difficult to learn how to support plants in this tender state.
A good medium for cuttings that will support their root development can be created with equal parts of vermiculite and perlite. Some growers opt for sand in addition; either supplementally or in equal parts to the vermiculite and perlite. Ultimately the goal is to create a mix that is light and porous so that developing roots can get enough air and water. Good drainage is essential as cuttings will rot if the media holds too much moisture.
When preparing cuttings, it is important that there is some amount of leaf surface area but not too much. You want the cutting to be able to photosynthesize light, but also not have to support too much foliage while it is trying to develop roots. Indirect light is also best for root development so that the portion of the cuttings above the media line are not prone to drying out. Cuttings are only getting moisture from the leaf surface or through the stem until the roots have developed. In no case should any fruit or flower remain on a cutting that you are trying to root.
Hardwood cuttings, those that are not bendable, can be more difficult to establish roots on. To aid in this process, it is good practice to wound the cutting by stripping off a vertical slice of bark about half the length of the cutting. This healing process will aid in the development of roots. Softwood cuttings are typically much easier to set roots and this step does not usually need to be added.
Keep the rooting media warm while cuttings and clones are trying to develop roots. Ideally the temperature will be between 65 and 75 F (18-24 C). Heating mats can also be used if the ambient temperature is too cold.
Before we look at how to get your cuttings to sprout healthy roots, let’s consider what nutrients are needed for root development.
Rooting Nutrients and Fertilizers
All plants need different nutrients in differing quantities throughout their various stages of development. Phosphorus (P), and Potassium (K), are two of the most important nutrients needed for root development. These particular nutrients encourage plants to grow strong, dense roots and to strengthen and bolster their existing root network.
Fertilizers and nutrient solutions containing each of these are important during phases where your plants are actively growing and especially during their more formative stages. It is relevant to note however, that these two nutrients also help to develop flowers and fruit set, so that it is important to time these applications and not continue to give them to your plants once they have begun or passed the flowering stage. Applying these early on, will only encourage root development, which is what is wanted at this stage.
All commercially produced fertilizers print at least three numbers on their label. These represent the percentages of nitrogen, phosphorus, and potassium and are referred to as the N-P-K ratio. Nitrogen supports the development and growth of branches, stems and leaves, so at the outset, it is not needed in high quantities when root development is more important. If given to plants too early, they can sprout new growth too quickly and become “leggy”.
The two numbers that follow the nitrogen number should be higher than the first number if root development is the desired goal. For example, a fertilizer that has as its formulation 5-20-10, has 5 percent nitrogen, 20 percent phosphorus, and 10 percent potassium. This is a fertilizer formulated for root development. If in this example there is a 20 pound bag of 5-20-10, then it has 1 pound of actual nitrogen, 4 pounds of actual phosphorus, and 2 pounds of actual potassium. The rest of the weight is filler material or carriers for the nutrients. If you need to apply a half pound of phosphorus to your media mix for root development, then you would need to add 2.5 pounds of your 5-20-10 mix because 20 percent is phosphorus and .5 is 20 percent of 2.5.
You may not want to rely on a commercial fertilizer for your root nutrient needs. There are many great natural sources of each that can be used. It is just worth knowing that when using organic sources of nutrients versus chemical sources, the organic nutrients take longer to break down and are not available to your plants as soon as the water-soluble chemical sources which are found in most commercial formulations. The benefit though is that they will release their nutrient package over a longer period of time so they do not have to be reapplied as often. It is often good practice to use a combination.
Natural sources of phosphorus include such materials as bone meal, or rock phosphate. These usually do not contain nitrogen or potassium unless they are mixed in. Kelp, ground granite meal, greensand, and even wood ashes are great sources of potassium. Many of these naturally-sourced resources also contain trace amounts of micronutrients and other elements that are beneficial to plant development such as iron and magnesium. When dealing with a cutting, clone or young plant that has little to know roots of its own yet, it is important to stimulate that root growth as soon as possible. This is where rooting hormones come in.
Rooting Hormones and How to Use Them
Rooting hormones are not just for difficult to root species, they can be used for those that don’t typically need additional assistance. These products help by accelerating root formation as well as total number of roots and the uniformity of their development. Prior to using any of these products, it is important to have your media ready to receive the cutting once the hormone or stimulator has been applied.
The market abounds with all kinds of rooting hormones that can be used to aid in quick root development for cuttings. Root-developing hormones may come as a rooting powder, plant rooting gels, or even liquids. Though the manner of application and use differ, their purposes are the same- get those cuttings developing strong and healthy roots as soon as possible.
The specific how-to’s for each product will differ based on its formulation and may even be species specific. Make sure to follow all directions on the packaging label entirely and completely. In all cases, leftover product should not be reused or saved for a future batch.
Powders: Rooting hormones in powder forms are embedded in a carrier, most often talcum powder. Growers should not dip the cut end directly into the container. A small amount should be tapped out into a bowl so that the entire batch of hormone powder does not get contaminated. To use this type of formulation, growers should dip the basal (cut) end of the cutting directly into the powder. Excess should be gently tapped off and then the cutting should be placed directly into the waiting medium. Cuttings should be dry when using this method so that the powder does not clump and become more difficult to use.
Liquids and gels: Rooting hormones available in liquid form are embedded in either a water or alcohol based solution. The procedure for use for either liquid or gel-based rooting hormones is essentially the same as for powders. The cutting should be dipped into the water or gel and then immediately placed into the media. This should be done as a “quick dip” with submersion lasting only between one and five seconds maximum. For those formulations that use an alcohol-based carrier, it is important to keep the cutting vertical so no solution runs down and makes contact with the meristem (top or tip of the cutting where leaves or nodes are). If this occurs, a condition known as epinasty can occur which causes the leaves to twist and be malformed.
Sprays: Hormone sprays may be formulated to be applied to the base of the stem prior to inserting into the medium or as an application afterward. Post-stick rooting sprays are becoming more popular because of their ease of use. As their name implies, these are applied to the cutting after they have been placed in the medium. They should be uniformly sprayed on a batch of cuttings to the point of run-off. This needs to be done as soon as possible, but in no case longer than 24 hours after the cuttings have been set in their media.
These formulations contain naturally occurring plant hormones known as auxins. A look at the ingredient list on a container of rooting hormone may have such items as indole butyric acid and naphthylacetic acid. These are types of synthetic auxins. There are others and even natural sources of rooting aids for your cuttings and young plants. All types of plants can benefit from the use either. When developing roots, your plants don’t know the difference between a natural or synthetic auxin.
For growers that may not want to use commercially-produced rooting hormones, there are natural products that can be used instead. For centuries and probably longer, growers have taken advantage of the natural antibiotic properties of honey to use as a rooting stimulator. Cuttings can be dipped right into regular, off-the-shelf honey and then placed into the waiting media.
Salicylic acid, which comes from the willow tree and plants can also be used as a natural root stimulator. Branches and freshly cut stems of willow can be placed in a bucket of water and allowed to sit overnight. Remove the branches and bigger pieces and then strain the remaining liquid into a container that cuttings can be dipped in. With either of these methods it is difficult to impossible to know how much product each cutting is getting, but they are both proven methods that have been used for a very long time.
Rhizopots
An additional product that is excellent to aid in the development of roots, is the Rhizopot. Rhizopots are a durable fabric alternative to traditional plastic nursery pots or fragile clay ones. Plastic or other hard-walled pots are not great options for longer term root development in plants. These types of containers cause growing roots to circle the inner wall as they grow. This can lead to an ultimate “choking” of the main plant and ultimately death if not addressed.
Roots do not properly develop the fibrous hairs that are needed for water and nutrient uptake in classic nursery pots. Rhizopot fabric containers help your plants to grow faster, maintain good health, and ultimately lead to high yields. The stifling of root development in plastic or even clay pots is not the only potential issue that can cause harm to your plants.
Rhizopots allow your plant’s root system to breathe. Normal nursery pots are often black or other dark colors. When exposed to the sun, these can easily heat up your plant’s roots to well over 120 F (49 C). In the same conditions, a rhizopot will not exceed 90 F (32 C), which does not put the roots at risk of lethal heat damage. Then there is of course the issue of drainage in hard-walled pots.
Traditional pots generally have either one single drainage hole at the bottom of the pot or up to four along the bottom. It is of course critical that not too much irrigation water runs out or leaches through. Plants need access to moisture and nutrients that are in the media and if too much of either leave their container, their growth can be retarded or worse. Not enough drainage on the other hand can be equally if not more damaging.
If excess water cannot drain through or if nutrients reach toxic levels and cannot be leached out, root systems can suffer and die if the situation is not resolved. Poor-draining medium can also allow for the development of many fungal diseases like molds and mildews. Fabric pots like Rhizopots allow for the drainage of all excess moisture when your media has had “its fill”.
Rhizopots allow for the continual air-pruning of a plant’s root system. This leads to a better-branched root system and a more robust network of root hairs. Root pruning is achieved when a root tip reaches one of the many pores in the fabric container. Instead of hitting a hard wall and then having to turn to keep growing, the root tip is exposed to air, which dehydrates it and it dies. Though it may seem counterintuitive, this is a quite normal and healthy process.New roots are then produced from the end of the dead root tip which in turn find available pores, dry out, die and form new ones. Hard-wall containers are sometimes sprayed with copper to achieve a similar effect, but Rhizopots allow for the process as it occurs naturally.
The sum total of all of these benefits that the Rhizopots provide are improved root distribution and increased development of root hairs. This is not where the overall benefits end though. Unrelated to their benefits to roots, Rhizopots are more environmentally friendly than plastic growing containers. They are made of eco-friendly containers and are reusable. They also fold up when not in use so take up less storage space than most hard-walled pots.
