Part IV: Transplanting Adenium Seedlings (with 2020 update)

Updated February 2015

So you have successfully germinated adenium seeds. What's next?

Adenium seedlings are not really delicate or sensitive. In an emergency (say, someone knocked your pot off the shelf or a cat sat on your week-old seedlings), you can repot them anytime. If sowing and germination has been uneventful; you can wait a couple of months, maybe more. Usually though, seedlings in their cribs will start demanding more nutrients and the more aggressive ones will siphon supply off of their neighbours, leaving you with runts. To avoid this, it is usually better to move the seedlings into their individual pots after two to three months.

At two months, all 7 seedlings have already developed an extensive root system. I'm glad I sowed them in a container deep enough to allow them to do this without getting tangled with each other. I didn't want to have to rip them apart. Even then, the seedlings were so close to each other, they would have been all tangled up if I had waited another month before separating them.

Preparations
 You will need:

• Potting medium (1 part potting soil mixed with 1 part perlite)
• Pots (my best suggestion is 16-oz deli containers)
• Sharp cutter
• Screening material
• Pair of scissors

Choosing Pots
I debated whether to just use nursery pots. But in keeping with what I wanted the roots to do, I decided to use 16-oz deli food containers that I already had lying around from various food take-outs. They are the right dimension in that they are wider than they are tall--about 4.75 inches in diameter and 3 inches tall. 

I originally thought that since these deli cups were semi-transparent or even transparent, that will let me visually inspect if the seedlings need watering or not; maybe even see the roots getting fatter in the pots. This works in theory but in practice, the transparency of the deli cups allowed photosynthesizing fungus to grow inside the pot. They do not harm the plant but they are annoying to look at so you may want to reconsider this option.

As an alternative, you can also use 4-inch plastic nursery pots, plastic cups or whatever you have lying round, really, as long as they are no bigger than 4 inches in diameter at the top. The reason for the size limit is this: the bigger the pot, the longer it will take for the soil to dry out and the longer your seedling roots will sit in sopping wet soil. This will make them rot-prone. I do not recommend clay pots because you will be repotting these seedlings again. They grow pretty fast.

If you decide to reuse plastic containers, you need to punch drainage holes in them. You will have to cover the holes with bits of screen to stop the soil from falling out.

With a sharp cutter, cut out drain holes like so. 

Potting Mix
If you already have experience with gritty mix and you are wondering whether adenium seedlings will do well in them, the short answer is no. Seedlings up to a year old need way too much water to thrive in gritty mix, even the 5:1:1 version. So I use ordinary, store-bought potting mix, combined with a hefty amount of perlite at a the ratio of one part potting soil to one part perlite. This proportion qualifies this medium as sufficiently airy for adenium seedlings.
 
Digging Out Seedlings
Loosen the soil in the germination pot by shaking it a bit. At this point, there is already enough roots in there to hold the soil together, you will need to dislodge them gently. Then, use a spoon to dig out the seedlings one by one. You want the soil to be a little moist so it doesn't fall off as you lift the plant with the spoon. I found that this reduces the possibility of ripping out the roots in the process. Then, you can carefully shake and brush off the soil, then wash the rest off gently in tepid water.

Spooned seedling

Check out the roots in this 2-month old seedling, cleaned out

Potting Up
This is the best part.

I have 7 seedlings I can play with. The smallest of the seedlings was potted normally, watered and set aside. Be careful not to bury the seedlings. The plant itself is clearly marked to tell you where the soil line should be when you pot it. Note the abrupt change in the color of the stem where it is exposed.

The easiest thing to do is to just stick the thing into the soil and be done with it. I elected to experiment with several things.

Trimming the taproot. The picture above also shows where I cut the tap root off of some seedlings. I have seen cut lines much more radical than this, almost close to that light green part. The idea is to coax the plant to channel root growth to the feeder roots. For seedlings I intended to eviscerate this way, I selected the ones with the most number of feeder roots growing above my cut-line. This way, they will not lose too many of their existing roots because I merely want to direct root growth, not restrict it.

Obstacle course. I have seen videos online of adenium growers potting up their seedlings with various debris to encourage the roots to grow through, over and around them. In time, I bet creating this obstacle course will give you a plant with an interestingly contorted root ball.  They use anything from pebbles and marbles to bits of plastic material. So I plopped some rocks into a couple of the pots and placed seedlings in their midst, carefully arranging the roots in and around the rocks.

Discs. With a pair of scissors, I cut roughly circular pieces of plastic of different diameters (the smallest is about half an inch which will probably just annoy the roots). The pots were filled up to within an inch of the rim. Then, I placed one disk on top of that soil this way:

Er...

After the inspection, place the seedling on top of the plastic disk so that the roots are spread out towards the sides of the pot. Alternatively, you can also bundle them up on top of the disk. I've seen a lady on YouTube actually braiding the roots of her seedling but I will have none of that.

Then, also using a spoon, fill the pot up to the soil line marked on the seedling. Water slowly but generously until the soil is thoroughly wet.

All done

My first batch of adenium seedlings were planted in these deli cups and stayed in them for the remainder of the summer and then throughout that winter. The following spring, they were all dug up for root inspection and repotting. These deli cups do not last long and will eventually become brittle. After a full season, though, you will have a better idea how to repot them after a year. Some of these seedlings needed bigger pots, some stayed in 4-inch pots and some were combined into one pot just to see what they will look like after a year. 

Care and Maintenance of Repotted Seedlings
Once removed from their crib, these seedlings can almost survive as much abuse and neglect as adult plants but only just. This is the crucial time when your seedlings will start to develop their individual character and you want to give them good stuff to work with.

Watering:  
Once in their separate pots, watering should be a breeze. You can judge the pots by weight--if too light, they need water. If still heavy, even if not visibly moist, they can wait a bit longer. I prefer this method over having a weekly or biweekly schedule that no one can keep track of anyway. Just keep in mind that seedlings need slightly more water than your adult plants. At this stage in their growth, they are closer to coleus than succulents. 

Feeding
Adenium seedlings can be fertilized with half-strength fertilizer from hereon, once in two weeks. If you are like us and don't want to bother keeping track of such a schedule, add quarter-strength fertilizer every time you water. Seedlings like to be fed. The rule of thumb "feed weakly, weekly" works very well from late spring to late autumn.

Take note that this feeding schedule is for seedlings that are out there in the heat of the full sun. If you feed your seedlings this much without giving them as much light as they need, they will grow fast but they will be etiolated and weak. Balance is the key. 

Seedling Problems
Adeniums less than a year old are normally very sturdy things. A magnifying lens is your best tool to examine them closely and find early signs of pests. If you see any, a dilute solution of 4 parts water and one part alcohol is good enough for treating early infestation. Horticultural sprays will work well too, but they stink more. 

Always treat your seedlings--or indeed any plant--at dusk. Liquid treatments will form beads on your plant and these beads magnify the heat of the sun, causing burn. Spraying plants at dusk or at night will allow the solution to work overnight with enough time to dry out by the time the sun rises the following day. Regardless of the level of infestation, two follow-up sprays are usually advised, just in case there are stragglers. 

Seedlings also react quicker to stress than adult plants. 

• Yellowing of the leaf tips, for instance, is usually a sign of nutrient deficiency. Review your feeding schedule. 
• Browning of the tips is often a sign of under-watering. Adjust accordingly
• Bleaching of leaves are caused by moving the seedlings into full sunlight too quickly. You can not reverse this process once it has happened. Just remove the damaged leaves and next time, acclimatize your seedlings before moving them directly under the sun. Have them spend a week in dappled sunlight, then another week or so in morning sun. After that, they are usually good enough to move out. 
• Curling of leaves are usually a sign of pests especially when it only happens with new growth. Examine the seedling with a magnifying lens--pests usually prefer new growth since they are softer and probably tastier to them. Sometimes, however, some adeniums are just weird and their leaves will curl for no apparent reason. You just need to rule out pests first. 
• Dying leaves could be a sign of more serious problems under the soil. Dig out the seedling and examine the roots. Even if you can not see anything wrong, wash the roots anyway and treat with horticultural oil spray. Leave it out to dry overnight before putting it back in a clean pot with fresh soil. Just pluck out the dead leaves.
• Bottom leaves turn yellow and fall off as they age. This is normal if it is happening to the oldest leaves of your seedlings.

Winter Care (Updated after years of experimentation)
These little brats will not go dormant on their first winter. Maybe one or two will do that but mostly they will not. This gets a little tricky because if you are like most people, you probably have been sowing seeds by the hundreds before you realized there is that shit in the horizon called winter. 

Unlike adult plants which you can defoliate and store somewhere during the winter, you will have to provide for your seedlings for the months it takes to bring temperatures back up. Seedlings will need 14 hours of artificial lighting throughout winter indoors. There is no shortcut, there are no window solutions that will prevent your plants from stretching and turning lanky from lack of sunlight. You will absolutely need artificial lighting. A heated greenhouse is perfect but if you do not have one, you will have to install artificial lights for your seedlings to maintain their form. 

Or, well. Lacking these options, you can put your seedlings on a south-facing window sill and goodluck. When it develops elongated, gangly growth, just hack that off in the spring. It will be fine. 

Pro Tip: The best solution is to hang up a couple of T5HO fluorescent shop lights on a shelving system, hook it up to a 14-hour timer and put your seedlings under the lights, as close as two inches from the bulbs. You can put this setup in your house or in your basement, as long as the temperature does not go below 10C. Remember that indoors, your seedlings will slow down a little bit. You will have to adjust your watering and feeding regime depending on how warm it gets in your house or in your basement.

My recommendation is to get one of those 4-bulb panels. I use a lot of the 28-watt LED blurple panels for the bulk of my succulents but for my adeniums, I use fluorescents.

The advantage of fluorescent lights, especially T5HOs is that they are, ironically, not as efficient as LED lights. Fluorescent bulbs generate and give off a lot of heat. But this is heat that you need to keep your seedlings warm during winter. This way, you will not have to have separate heating mats to maintain the temperature. My adenium shelf typically averages around 30 to 32C even in the middle of winter and that is plenty warm for seedlings and adult plants. 

If you have a dedicated plant shelf, put your adeniums on the very top shelf so that the heat coming off of the lower shelves will also contribute to warming your plants.  

Feel free to ask questions!

Next: Part V Adenium Seedlings: Merciless Pruning 
Related posts: Seedlings Care after Germination
                       Adenium Seedlings: One Year Later
                       Adenium Seedlings: A Year in the Tropics