Euphorbia Milli in a Pot in My Garden - Welcome The Crown of Thorn!

Euphorbia milii

The Crown of Thorns is a woody, multi-stemmed, succulent shrub that originated in Madagascar.
Dark green, tear shaped leaves appear randomly on each thorn covered branch.
When a Crown of Thorns plant becomes stressed due to over watering or under watering, humidity or temperature changes, it may quickly drop all of its leaves.
Normally, once the cause of stress is resolved, fresh foliage will quickly return to your plant.
Crown of Thorns will produce flowers nearly all year, but especially during the winter months.
The tiny flowers are insignificant but appear just above brightly colored red or yellow bracts.
Because of their leaves, most people don't consider a Crown of Thorns to be a succulent plant, but in reality it is. They have limited water storing abilities, however, and often have to rely on moisture it takes in through its leaves so I would try misting your plant daily. You might also want to increase the amount of water you give it each time you water it.
Crown of Thorns plants should be watered once a week when it is in a growth cycle, but only once a month while dormant. Whether dormant or actively growing, never water before the soil has completely dried.
Once you have resolved the leaf drop issue, you should start feeding your plant monthly with fertilizer to get your plant blooming again.
Crown of Thorns plants should have some direct sun each day, even if it just an hour or two.

Propagating a Crown of Thorns Plant

CAUTION!  The white milky sap is VERY poisonous, use gloves and wash your hands thoroughly afterwards! First of all, you need to cut any of the rotted branches back to a point where you find clean healthy growth.
If the rot started in the roots you may only be able to salvage a lot of cuttings, however if the rot is only at the branch tip, you can cut it back to healthy wood, and your plant will come back from the rootstock. It is possible to take and root cuttings from a Crown of Thorns plant but they take a little more effort and time than most cuttings.
Using a very sharp, clean knife (I like single edge razor blades) cut a branch off at the point where it meets the main trunk.
Set the cuttings aside in a cool dry place for two or three days to allow the cuts to callous over.
Once the callous has formed, dip 1-2 inches of the cut end into a rooting hormone, such as Roottone®.
Insert each cutting into a clean pot of sterile, sandy potting soil.
The pot should then put in a warm place with bright light. Do not water at all for the first 2 weeks, and then you can begin watering the cuttings very sparingly until you see signs of new growth (usually in about a month)
Rooting will be faster if the soil is kept at a constant 75° F.
I suggest that you take several cuttings to be sure that you succeed with at least one of them.

Description

It is a succulent climbing shrub growing to 1.8 m (5 ft 11 in) tall, with densely spiny stems. The straight, slender spines, up to 3 cm long, help it scramble over other plants. The leaves are found mainly on new growth^] and are obovate, up to 3.5 cm long and 1.5 cm broad. The flowers are small, subtended by a pair of conspicuous petal-like bracts, variably red, pink or white, up to 12 mm broad. The sap is moderately poisonous

Dangerous/Poisonous:

As with other euphorbs, Euphorbia milii produces abundant quantities of poisonous milky sap that causes skin irritation. The sap contains diterpene esters, which are tumor promoting chemicals. When handling all Euphorbia species one should wear gloves for protection.