I live in Las Vegas Nevada. Where the temputures can be very and very cold. My Queen of the night plant is dying. I’m sending you a picture hoping you can help. Thank you
Thank you for reaching out to the Toronto Master Gardeners.
Queen of the night, Epiphyllum oxypetalum, with its spectacular fragrant flowers, is native to Mexico and Central America. It is also known by the common names: Dutchman’s Pipe Cactus, Jungle Cactus, Lady or Queen of the Night Cactus, Night-blooming Cactus or Orchid Cactus.
It is suggested that you take several cuttings of what remains of your plant in an attempt to grow new plants from what is viable. Ensure that you disinfect your cutting tool between each cutting.The Epiphyllum Society of America “Cultural Information” (see link), outlines steps to take in growing cuttings and plant care.
It might also be wise to gently remove the plant from its pot to assess the roots for cold damage or root rot. If there are healthy viable roots, the plant may regenerate from these. Repot in potting mix as listed in the cultural information resource above, in the same size or smaller pot, depending on the size of the root ball (ensure your potting container has drainage holes in the bottom).
The leaves in your photo, along with the dry brown areas which might be cold damage, appear to have some sort of viral or insect damage. This site (see link), also has information on common pests and diseases.
Master Gardener groups are generally specific to their regional areas for ASK a Master Gardener questions. You may wish to explore various resources available in your area such as: Master Gardeners of Nevada . If you scroll to the bottom of this home page, you will find a list of Master Gardeners in your specific area. You also may pose your questions via the ‘Contact Us’ form.
For further general information, please see links, ‘About Epiphyllums’, Orchid Cactus, and How to Grow, Bloom . . .
Hopefully this information helps you with a direction in going forward in caring for your plant.
Wishing you all the best.