Cacti are generally very resilient, but they can be susceptible to issues in the seedling stage. when transplanting a cactus seedling, here are some tips. At World Seed Supply, we usually send cacti seedlings bare root to save on shipping. This means the cactus seedling will be shipped without soil, something that is fairly common when it comes to cacti. Cacti will have no problem lasting without soil or water during a trip in the mail. Even seedlings, can survive weeks without water. Larger cacti can go months, even over a year without any water. The following guide is intended to help you transplant columnar cacti seedlings.
When you get your cactus seedling, you will need a pot and soil. Any commercial cactus soil will work, such as Miracle grow or (we prefer) Schultz’s. You can find these in most garden centers year-round with the rest of the bagged soil. You can use anything as a pot, but you are best off using a smaller pot than something big that the plant will grow into. A bigger pot with more soil seems to increase the chances of rot. A 3″ seedling can do well in a standard 8oz. foam coffee cup or similar size pot. Something smaller will suffice too. . Although clay pots are common for cacti because they suck out excess moisture from the soil, we do not like to use them. We prefer exercising more control over the watering by just giving the plant the proper moisture.
The most important thing in transplanting a cactus seedling is to make sure the base of the cactus seedling stem is well-supported. If the cactus stem is leaning, that puts internal pressure on the vascular system of the cactus seedling, and that pressure seems to cause rot in many cases. This scenario is like cutting of circulation to your extremities. It can eventually cause them to die. So you want to ensure you bury the cactus seedling enough that it will stand on its own. Secondly, you want to make sure the soil is packed firmly enough to keep the plant standing. But if the plant has a tendency to lean, the pressure of the plant’s weight can displace the soil over time and let the plant fall. So we often recommend staking the cactus seedling on both sides.
You can use a wooden skewer or some unfolded paper clips to make supports on either side of the cactus stem. Twisty ties, such as those used to tie bread bags, are a great way to secure the plant to the two supports. They are much easier to undo than string, and you can mold them into a spiral pattern that leaves virtually no pressure on the stem. It is vital that you do not secure the cactus too tightly. You’re just looking to help prop it up until the roots grow deeper and the stem strengthens.
“When to water” and “How much?” are perhaps the most pressing questions new growers have when transplanting cacti seedlings. You must consider that when being transplanted the roots have been damaged to some degree when the cactus seedling was uprooted from its former location. Cacti have the ability to root from a cutting without any roots, so losing some roots should not prevent the plant from being transplanted. But the damage can be a place where pathogens can enter the plant. So it is a good idea to give the plant at least a week or two to heal before you water. It can help to dip the roots lightly in rooting hormone powder before you transplant your cactus seedling. When you eventually do water, you want to spray deep into the soil. Try to keep moisture off the cactus seedling stem. This will keep the potential for rot down and encourage the roots to grow outward. Once the cactus seedling has been growing stable for a while, it is a good idea to water from below the pot and let it draw up moisture or spray between the soil and the pot so that the water pools down below. Your overall moisture needed is dependent upon things like light, temperature and whether your plant is in active growth. There’s not set amount to water because it depends on how fast the water is evaporating and how much water your cactus is using at the current rate of growth. But initially, you just want to water enough that the plant will not totally dry out. Generally, this requires less water than you expect.
Success in transplanting a cactus seedling is dependent upon it getting back into growing mode. You can do this with proper lighting. NEVER, put a cactus seedling directly outside. You think of cacti as being able to handle harsh sun, but this is sure to fry a cactus seedling. We usually recommend starting your cacti seedlings under fluorescent lights. T5, which are the skinny tubes, are the best. But you can always use a simple CFL bulb in a desk lamp.
Window light is usually not enough to keep a cactus seedling growing well. it will often grow fast and skinny. The fast growth is not ideal. The plant will not fatten up. Cacti and other plants do this to get an advantage on other plants they perceive to be blocking out their light. They grow tall to reach up over where light may be, but it creates a lack of support for future growth. If you see this, you need more light. If you see the stems turning red, they are sunburning. A harsh sunburn will cause the cactus stem to scar. You may get some reddening if your plant is too close to a fluorescent bulb, but it will usually not scar if you are careful. So this that is why these lights are recommended. Only attempt transplanting your cactus outside when it is past the seedling stage. And even then, you must acclimate it slowly.
Aside from this, it is a good idea to keep a fan blowing on your seedlings. You do not want the fan blowing your cactus seedling over. Just keep enough air flowing to circulate it. That will give the plant the carbon dioxide it needs to keep healthy, and it will keep enough oxygen in the area to limit the growth of other pathogens.
Cactus seedlings are live organisms, so transplanting always puts them at some risk. But knowing the proper techniques you can do to support seedling growth is always helpful. If you keep all the techniques in the guide in mind, it will give your cacti seedlings the best chances of a successful transplantation, and you will go on to raise happy healthy cacti from seedlings.