OKKAYYY I got this cutting as a gift and was told to put it in a small vase of water, change out water weekly, and wait for it to root.. Well, my sister in law did the same thing and hers started to grow small leaves at the top and then it rotted from the bottom up. Mine started growing leaves months after her plumeria, but after hers rotted, I started doing research and got scared it would die from too much water and that potting it was a better solution... So naturally, I panicked because I want this shit to grow nice and big!!! I went to the store and bought Miracle-Gro cactus, palm, & citrus potting mix (fast draining formula), Miracle-Gro perlite, & Brotone II Rooting powder. I mixed it all up, dipped it in the powder, and planted that thing as soon as I got home. Obviously I have no idea what I’m doing and need some help on what to do. The leaves were already purplish before potting and I potted it a couple of days ago as well as watered it. I have not watered it since because the soil has stayed damp, which I feel like is a bad thing? The two bigger leaves have grown a bit more since potting I FEEL like. The top of the soil (I assume from it staying damp) had little specs of mold on it so my brother suggested I mix in some Diatomaceous Earth.. and I did. Not sure if that was a bad or good move and I also made sure the holes on the bottom of the pot weren’t clogged. Should I completely repot and get smaller pot? I think this is 2 Gal. Someone PLEASE help me I have absolutely no clue what I’m doing and would love to gain the knowledge. Thank You! (https://i.stack.imgur.com/vmeFW.jpg) (https://i.stack.imgur.com/lxeAy.jpg)
Don't over-think it, as long as it has drainage and is watered occasionally , not wet, no fertilizer, it should grow. In Houston area they are sold as a foot or two of bare wood and all the way to a blooming plant in a large tub. I understand , some have success sticking the bare wood in the ground in a shady spot in the garden ; I would put them in a plastic bucket with a shovelful of soil. When it grows leaves and roots in a couple months, it will need full sun if you want blooms. They were easy to grow, I gave them up because I could not give them enough sun for more than an occasional bloom.
Plumeria is normally taken from good cuttings at least as long and thick as your middle finger. This gives the cutting a lot of stored food in the cutting to survive the month or so as it makes roots, and will be plenty of food to produce leaves at the tip before any roots are formed. When preparing the soil to receive the cutting make sure the soil is moist but not wet; you should be able to take a handful and squeeze it into a ball with zero moisture coming from your hand. Just moist enough to keep it together. Once potted up keep it in a humid, warm, protected place, and only water it enough to replace the water lost from transpiration and evaporation - you can track this by weighing the potted cutting and only adding water to bring it back to that weight. Too much water and the cutting rots.
You rescued it by pulling it out of the water! Good instinct!
I have been keeping Plumeria in Dallas area for several decades and have about 42 semi-dormant Plumeria in my heated garage right now, 12 are trees (Temps below 42 can kill them). There are times when you will want to take cuttings from your tree when it gets big and this is a pretty good video that explains the entire process from cutting to rooting a cutting. When rooting a cutting you will want to keep it on the dry side. I highly recommend a rooting hormone powder that you can get at the store. Wet about 1-1.5 inches of the end of cutting and dip it well in the powder. Then, stick the cutting in your rooting medium and try not to move it around much while rooting. Water it well once then let the soil dry out completely. This encourages rooting and minimizes losing cuttings to rot. The sun and warmth is what will force rooting, and keeping it on the dry side. Everyone has their own process. But, I usually wait about two weeks and water again in 85+ Fahrenheit weather with pots sitting on concrete in full sun, which means the pot has been dry for about 10 days after I last watered it. It won't root well in temps below 75. Continue that process until you see a couple sets of new leaves. This is when new roots have formed. I usually wait until 4 leaves have formed and then carefully repot the cutting to its new home. When you get 10 leaves or more you can step up the fertilizer to 1/2 strength. But, I only give it full strength rarely when trying to force flowering on a 6-9' tree in the Summer. Otherwise half strength is fine for Plumeria, and more economical. I like Carl Pool's BR-61 as a fertilizer. The combination of this and 8+ hours of direct sun will help force it to bloom. This fertilizer has gotten a little more pricey and may have to be purchased online, but it has a very large Phosphorous number (the middle number of the NPK rating) which is all you will ever feed a Plumeria. Green Light Super Bloom is another good fertilizer for Plumeria. Other tips: A cutting will usually take about 3-5 years to start blooming. You never want to use Nitrogen fertilizer (high 1st number) on a Plumeria, ever! When you take cuttings from the plant, let the cut end dry and harden for at least a week before trying to root the cutting to avoid allowing disease and insects into the cutting. Then use the rooting powder as described. Placing the pot in full sun on concrete ground to warm the pot is great, it encourages rooting and speeds of the rooting process. Cold, dark and wet feet are it's enemies! Full sun and warm feet is its friend! Good Luck! https://www.youtube.com/watch?v=QHQ777SALj0