I just realized I started my moonflower and morning glory seed about a month (probably a bit more) early. The last frost date in my area is May 8th so I can't set them out until then. I believe that these plants grow very quickly - right now they're about 5 inches tall or so and will soon need some support to start vining. The morning glories in particular are growing fast. I do have them under a small grow light. Is there any way I can save them? I was hoping to grow them in containers outside. Or should I just start over?
My inclination would be to get them where it's about 40ºF and less light. That should slow them down a lot. Will it save them I don't know. You can also just start over. I've just planted them outside so I'm not sure of the timing for an inside start.
" Is there any way I can save them? I was hoping to grow them in containers outside."
Start by growing them in containers inside. You can grow them indoors to the flowering stage and beyond. Many morning glory hobbyists have developed techniques for doing that. I suggest you bring this question up in the Morning Glory forum:
One of the first things you will need to do is re-pot them to larger pots. And as they grow even larger, you may need to repot those larger pots to even larger pots. I am a zinnia hobbyist. Zinnias aren't houseplants, but I have grown them from seed to seed indoors during the Winter. Regard this as a learning adventure, and post a query over in the Morning Glory forum to get the benefit of some really expert advice.
Professional growers use plant growth retardants to keep their plants from stretching too much. Those retardants do the opposite of what Gibberellin does. Gibberellin increases the internode-to-internode distance on stems, while the growth retardants decrease it, by inhibiting the natural production of gibberellins inside the plants. I have used Topflor with good results on my indoor zinnias, to keep them from stretching up and banging their heads on my fluorescent lights. I don't know about Topflor availability in Canada. A-Rest is another good growth retardant that I have used. B-Nine is another one, but it has to be sprayed on the foliage for foliar absorption, so that isn't really convenient for indoor gardening. The others can be applied as drenches or in bottom watering.
It should be possible to use various techniques to keep your morning glories and moonflowers growing almost bonsai-like in pots. Which could add a new dimension to the enjoyment of growing them.
I know a lady here on DG that grows them inside in her basement garden. She has a beautiful garden all winter in the basement of her house. She grows MG's in her basement as well. She has supplemented her basement with a lot of the clip on flourescent lights. If you would like, I can ask her to contact you.