Grown as landscaping plants in mild winter climates, columnar cacti can reach impressive sizes not possible when they're grown in containers. When cacti outgrow their allotted space or are reaching toward pathways, they need trimming. This might seem like a formidable task, since stem diameters can be large and some cacti have sizable spines along their ridges. Try to tackle pruning jobs before the stems get too large. With the proper equipment and planning, you can remove the unwanted growth.
Preparing to Prune
1. Mix a container of 10 percent bleach solution by combining 1 part household bleach with 10 parts water. Select a container tall enough that you can immerse the cutting edges of your pruning tools in it.
2. Wear protective clothing that covers your arms and legs, closed-toe shoes and gloves. Add safety goggles if your face will come anywhere near the cactus during the pruning process.
3. Study your cactus plant to determine a plan of action. Identify the outermost branches you wish to prune, and decide on the order of pruning so that you have easy access to the stems with the pruning tools. Then move to inner branches. Remove long, heavy branches that would be hard to handle in sections, taking manageable cuttings from the top down.
4. Select the proper tool for the size of stem you're working on. A serrated knife works well for smaller diameter cuttings and angled-blade pruning saws are best for larger diameter stems. Use a long-handled saw for hard-to-reach stems.
5. Dip the blades of saws or knives in the bleach, soaking all surfaces.
Making the Cuts
1. Grasp the stem in the middle of the intended cut location with cooking tongs if the stem is small in diameter. Put a piece of rope in the middle if the stem is larger. Continue to hold the stem with the tongs or rope while you make a clean slanting cut through the stem angled at 45 degrees. Get another person to hold the stem of big branches while you make the cut.
2. Remove the cutting and lay it on a clean tarp or piece of cardboard if you are going to propagate it. Place the cuttings in a garbage can or sturdy box for transport if you aren't keeping the cuttings.
3. Check the cut on the mother plant if you are only removing one cutting. Remove any torn or jagged areas and make sure the slanted cut is smooth and will easily shed water to prevent rot on the parent plant.
4. Continue to make cuts on the stem if it is a large branch, supporting each cut section with the tongs or rope as you go. Lay each piece of cactus on the clean surface or put it in the garbage can. Make sure you can tell the bottom from the top of each cutting if you plan to root the cuttings. Use a permanent marker and put an X at the bottom edge of each cut.
5. Discard the cuttings, give them away, or make more plants by rooting the cuttings.
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