I bought luffa seeds. I live in Colorado. How and when is the best time to try to grow this plant?
This article should help you: http://www.luffa.info/luffagrowing.htm
What plants need a trellis or stake? I am planting a lot this year and the package doesn't mention anything. Luffa, celery, green pepper, lettuce, tomato, etc.
Any plant that gets somewhat large or is vine-like in nature (tomatoes and luffa are good examples) would benefit from staking or trellising. Here is more information: https://www.gardeningknowhow.com/garden-how-to/info/supports-for-garden-plants.htm, https://www.gardeningknowhow.com/edible/vegetables/tomato/best-way-stake-tomatoes.htm, https://www.gardeningknowhow.com/edible/vegetables/pepper/stake-pepper-plants.htm, https://www.gardeningknowhow.com/edible/vegetables/beans/pole-bean-supports.htm, https://www.gardeningknowhow.com/edible/vegetables/gourd/luffa-gourd-planting.htm
I just bought 60 green luffa. Some have a little brown. How do I dry them so the luffa will be mature?
Most sources advise leaving luffa on the stem as long as possible. I hope yours aren't too green. These articles should provide information: https://www.gardeningknowhow.com/edible/vegetables/gourd/growing-gourd-plants.htm
http://www.luffa.info/
What insect is causing the flowers on my luffa vines to fall off as if cut about an inch below the flower hip?
There could be numerous insects that cause this issue of bud drop including thrips, aphids and mealybug.
Treat the plant with Neem Oil.
Here are some links for you.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/edible/vegetables/gourd/luffa-gourd-planting.htm
Last year (and now this year) there is a bug that chews the stem just behind the blooms of my Luffa squash. It's not just a bloom falling off. I've seen the bug, smashed one as I tried to gather him. Haven't been able to catch any more. I see one now and then. It looks like an ant with 2 sets of wings. Lobes at the end of the top wings... (is not a termite). The wings are black and clear lace, has a mouth like a Finch bird. Now it's started again. These are tender plants and can't seem to handle sprays like Malathion and Sevin liquid and dust. I'm using Diatamatious Earth (but, of course, it's washed off in the rain). I tried putting VASELINE where he chews behind the blooms last year, but the plant doesn't like it. I lost the bloom anyway. HELP!
Neem Oil is a good treatment for most pests.
Neem Oil is organic, safe for people, pets and bees.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
My Luffa plant is growing but there are no sign of flowers. Its just a long vine. What am I doing wrong?
Luffa grows and fruits quite vigorously, although they take longer than other squash varieties. Make sure they have plenty of sun, water, and you might want to add bone meal to your fertilizing to help encourage flowering and subsequent fruiting. This article may also help:
https://www.gardeningknowhow.com/edible/vegetables/gourd/luffa-gourd-planting.htm
I had to harvest them because it was freezing....but now they are still green and do not want to turn brown.
This is ok, and you can still use them. Here is a page that will give you more information on them than one could ever think of to ask about: http://www.luffa.info/luffagrowing.htm