How to graft cactus seedlings?
This article introduces the related content of succulent plants, cacti, specifically how to graft cactus seedlings. Let's find out more from the editor.
Some cactus species in the spherical cactus category have very fragile seedlings that struggle to survive on their own. However, if grafted onto a vigorous rootstock while still small, they will become vigorous. This is the early grafting of cactus spherical plant seedlings. This type of grafting can maximize the preservation of rare and difficult-to-care-for seedlings, allowing difficult-to-grow varieties to smoothly pass the seedling stage and speed up propagation. Taking the currently popular "Silver Crown" cactus as an example, let's talk about how to perform early grafting of cactus spherical plant seedlings under home conditions.
Preparing the Rootstock
Vigorous, stress-resistant, relatively easy to propagate, and compatible strong strains can all be used as the rootstock for early grafting of seedlings. For example, columnar cacti such as "Wolong Column," "Dragon God Column," and "XiuPu Column"; spherical cacti like "Flower Full Ball" (also known as grass ball) and "King Kong"; thick species of flat cacti such as the "Large Spine Cactus" and epiphytic species like "Holland's Column" are all common rootstocks.
Home grafting is different from the mass production in greenhouses. It is usually less in quantity but more precise. Therefore, it is best not to choose Holland's Column as the rootstock. Other rootstocks have their advantages and disadvantages and can be chosen according to needs. Taking "Dragon God Column" as an example, although it is relatively difficult to root, it is easy for the scion to take root after it is formed. In a home cultivation environment, if you want to use "Dragon God Column" as the rootstock, you need to prepare two months in advance to ensure that the rootstock is full and strong. The success of this grafting depends on whether the rootstock is strong, so it is necessary to choose a plant that is plump, strong, and has a well-developed root system as the rootstock.
Preparing the Scion
The scion can be selected from 1 to 4-month-old cactus seedlings. The scion used here is the "Silver Crown" seedlings sown in early June, which are about 2 months old when grafted in August (Figure 1). The seedlings for grafting can also be intentionally exposed to strong light for a period of time to make them more robust. Although these seedlings may not be as large as those kept in a humid environment, their plant tissue is dense, roots are well-developed, and they have strong resistance, which can increase the success rate of grafting.
Grafting Time
Grafting can be done when both the rootstock and scion are in the growing period, from mid-March to the beginning of October every year. In a home environment, choosing to graft between May and September, when it is relatively hot, is easier to survive. Of course, with the vast territory of our country and different cultivation environments in various regions, you should choose the best grafting time depending on the time, region, and environment.
Also, check the weather forecast before grafting to avoid consecutive rainy days. Because slow wound healing in humid conditions can easily cause the wound to become red and lead to grafting failure.
Preparing Tools
Make sure to prepare all the tools that may be needed in advance to avoid the embarrassment of searching for tools after cutting the plant. During the formal operation, keep all tools clean and strictly disinfect cutting tools. Common tools include: grafting knife, thin rope, tape, disinfectant, cotton swabs, tweezers, plastic bags, etc. (Figure 2).
Grafting Operation
Most home grafting failures are due to excessive water loss in the rootstock or scion, so here we recommend the "two-step" method, which is to cut the rootstock step by step to minimize the area of a single wound and maximize the survival rate.
The first step is to make a 30-45 degree oblique cut along the top of the rootstock along line A, leaving the central growth point (Figure 3). The red dot in the figure indicates the growth point. For "Dragon God Column," the growth point is usually about 1 centimeter below the top epidermis. Do not cut off the growth point; the cut must be slightly above the growth point. If you are inexperienced, you can cut little by little and not rush.
The second step is 15 days after the first oblique cut, when the rootstock's cut surface has healed, and a small bump has grown at the growth point. It's time to implement the second cut, which is to cut off the growth point of the rootstock. As shown in Figure 4, cut along line B, and the cut position should be just enough to see the central vascular bundle of the plant. This makes the cut at the growth point minimal, and the rootstock loses the least water!
After the rootstock is cut, immediately cut the scion (Figure 5). Make a horizontal cut at the junction of the stem and root of the prepared strong seedling, ensuring that the cut is smooth and precise (Figure 6), then quickly place the scion on the growth point of the rootstock, making sure to align the vascular bundles of the rootstock and scion completely or mostly overlap. Figures 7-9 are schematic diagrams of the two vascular bundles during grafting, with the red circle representing the rootstock's vascular bundle and the green circle representing the scion's vascular bundle. If the diameters of the two vascular bundles are similar and can be aligned and overlapped, it is the ideal state (Figure 7). In practice, most of the time, the two vascular bundles mostly or partially overlap, and the survival rate of the scion is also high (Figure 8). The worst-case scenario is when the rootstock is cut too much, the vascular bundle diameter is too large, and the scion's vascular bundle diameter is too small, forming non-intersecting concentric circles, which often leads to grafting failure (Figure 9). After that, apply pressure to the scion with medical tape or thin rope to ensure it is fully contacting the rootstock. When using medical tape, you can place a small piece of paper on top of the scion to avoid揭ning the scion when removing the tape. In a home environment, whether in the north or south, it is recommended to apply external force to increase the contact between the scion and rootstock, thereby increasing the survival rate of the graft.
Post-Grafting Management
In the south, avoid excessive humidity, and in the north, avoid excessive dryness. In a humid environment, the plant's wound is prone to red rot, while in an overly dry environment, the plant's cut can lose water and shrink, both of which can lead to grafting failure. In the dry season in the north, cover the plant with a plastic bag after grafting. After grafting, place the plant in a location without direct sunlight and after about a week, you can remove the thin rope or medical tape. If the scion is plump and shiny, and there is no obvious red rot or shrinkage at the grafting site, it indicates a successful graft. The successfully grafted plant can then be gradually maintained normally.
After the seedling danger period has passed, you can cut the scion to take root on the ground or continue to care for it on the rootstock to shorten the propagation cycle.
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