Why doesn't my well established moonflower plant have any blooms yet? It is thriving climbing a trellis in mostly full sun during the day.
It likely is lacking phosphorus. Plants need phosphorus to bloom. This article will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
I have a moonflower in a pot outdoors. How should it be cared for this winter? Left outside, brought in the house, cut back?
Since moonflowers are perennial in the tropics, you should be able to keep it indoors over the winter. You'll want to acclimate it to the lowered light over a period of several weeks https://www.gardeningknowhow.com/houseplants/hpgen/acclimate-plants-indoors-winter.htm
You'll probably want to cut it back some, and be sure to monitor soil moisture to make sure the plant doesn't stay too wet.
Frost has killed my Ipomoea calonyction (Moon flower). Large seed pods have formed, and I'm wondering when I should harvest them.
They are ready to be harvested when they are dry and brown. If you are worried about the cold damaging the seeds, you can harvest the pods green and then place them in a paper bag in a cool, dry place and they will dry there and be ready to harvest when the have turned brown in the bag.
You certainly want to gather them before they open. Here's a couple of articles that should help:
http://homeguides.sfgate.com/guide-harvesting-moonflower-seeds-45803.html
https://www.gardeningknowhow.com/ornamental/vines/moonflower/growing-moonflowers.htm
I bought moonflower vine plants last year and since I live in the North, they will not come back, so there were these little lanterns pods and when I broke them open, a white seed came out. I am hoping it is a seed because these flowers were beautiful.
Yes, those pods were from the moonflower vine plants and the seeds are indeed white. Here is an article that will explain more:
https://www.doityourself.com/stry/collecting-moonflower-seeds-for-next-season
For more information on growing moonflower plants, please visit the following link:
https://www.gardeningknowhow.com/ornamental/vines/moonflower/growing-moonflowers.htm
Do you have to cut back the moonflower's vine each year or does it continue to bloom on the same vine each year? How much sun does the moonflower need?
Moonflower blooms on new wood so you can cut the vine down to the ground in the fall. Moonflower prefers full sun.
For more information on moonflowers, please visit the following link:
https://www.gardeningknowhow.com/ornamental/vines/moonflower/growing-moonflowers.htm
What pest has developed on my moonflower? Leaves are gradually becoming more porous. Help!
It is difficult to say for sure, especially without any other symptoms or a picture. That being said, most insect pests can be treated with neem oil spray, which also doubles as a fungicide should this be an issue as well. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm
Do the plants produce seeds as they start to die out?
Moonflowers produce a seed pod after the flower petals drop.
The seeds are not mature until the pod dries. It should turn brown and feel brittle.
Pick them before they break open.
Each of the seed pods will contain 2 to 4 seeds.
Make sure the seeds dry completely before placing in jars or envelopes to store for next spring.
https://www.gardeningknowhow.com/ornamental/vines/moonflower/growing-moonflowers.htm