Bringing in plants, preparing pond for winter, algae question

[Phaewryn]

I have this sort of stringy/slimey algae in my pond since I have not been on top of cleaning it this summer, and I'm wondering if there is any benefit or detriment to leaving it or removing it as fall/winter approaches? If it's better to leave it, I can, but if it's just going to die and cause water conditions to deteriorate, I'll remove it before I cover the pond. I'm also not sure how soon I need to bring in my plants (zone 5a, southern Vermont): chameleon plant, water forget-me-not, marsh marigold, watercress. The forget-me-not and watercress is still very small/not well established. All of them except the marsh marigold are in pots, so easy to bring in. The marsh marigold is in the upper pool in pea gravel, which will freeze totally solid, so I assume it needs to come in, or perhaps be moved to the main pond, which I heat just enough to keep from freezing in the winter? Pics of algae below.

 

[Lisak1]

The algae will likely die off in the cold but I wouldn't worry too much about it. If it's easy to pull, I'd pull it. Otherwise I'd just leave it be.

If your plants are hardy to your zone (like the marsh marigold, forget-me-not, chameleon plant) they'll be fine to leave outside, even if they freeze solid. Just make sure the ones in pots stay below water. They'd rather freeze solid in ice than to be exposed to the cold. Watercress I'd also just leave alone. It may or may not come back, but it's cheap and a fast grower. I wouldn't bother trying to save it - just toss more in come spring if it doesn't come back.

 

[Phaewryn]

The algae will likely die off in the cold but I wouldn't worry too much about it. If it's easy to pull, I'd pull it. Otherwise I'd just leave it be.
If your plants are hardy to your zone (like the marsh marigold, forget-me-not, chameleon plant) they'll be fine to leave outside, even if they freeze solid. Just make sure the ones in pots stay below water. They'd rather freeze solid in ice than to be exposed to the cold. Watercress I'd also just leave alone. It may or may not come back, but it's cheap and a fast grower. I wouldn't bother trying to save it - just toss more in come spring if it doesn't come back.

The marsh marigold is for sure hardy here, but I wasn't sure it would like being frozen solid in pea gravel, which will expand and contract. Will that not harm the roots? I'm fine with leaving it out if it will survive freezing solid in 5-6" of pea gravel. I don't heat or keep water running to the part of the pond it is located in in the winter (it's in the top of the waterfall).

How do I manage the chameleon plant when putting it underwater for the winter? Should I cut off the foliage before putting the pot deeper, or will the foliage naturally start to die back after the first frost? Will the foliage survive totally submerged? I didn't think it would, it being a bog plant. It can't stay where it is once the cover goes on the pond as it sticks up too much to get the cover on with it like it is now. It either has to go deeper with the crown 6-10" below the water's surface with the foliage on it, have all the foliage cut or die off, or be moved out of the pond (it could go up the the top waterfall tier with the marsh marigold, I suppose).

The watercress was very hard to get started, and impossible to source here: I would rather save it if at all possible. It is not easy to start from seed and I have no access to any of it any other way. People here do not eat this stuff so it's not sold here in the grocery like everyone says it is everywhere else. It's just now beginning to grow at all. The forget-me-not is hardy here, but I wasn't sure if it is established enough to survive. Pics below of the watercress and forget-me-not (one with my hand for scale, it's not even palm sized). I'll probably just bring them in. It took months to get them even this started, I don't want to have to start over next spring only to just get this little growth again.

 

[Lisak1]

Any plant that is hardy to your zone can handle being frozen under the water. Like I said, they prefer that to being exposed to the air. Won't hurt them at all.

As for sinking plants in the pond - yes, cut them back as much as possible and then just... sink them! Again the goal is completely submerged.

You can bring your watercress inside and grow it in a glass of water in the windowsill. I've actually started some that way from cuttings when I was waiting for it to get warm enough outside. Just change the water now and again and it should be fine.

 

[Phaewryn]

Any plant that is hardy to your zone can handle being frozen under the water. Like I said, they prefer that to being exposed to the air. Won't hurt them at all.
As for sinking plants in the pond - yes, cut them back as much as possible and then just... sink them! Again the goal is completely submerged.

Got most of the algae pulled, left some on the deepest part of the pond, and got it all off the waterfall parts.

My problem is that my pond is heated in the winter so it doesn't freeze. The top tier of the waterfall will freeze solid, but the crowns of the plants can't be underwater up there. They either can go completely submerged under cold, but not frozen, water in the pond, or freeze solid with the crowns at the surface in the 4-5" deep gravel "pseudo-bog". I moved the chameleon plant up to the top tier with the marsh marigold (which never really did much), but I may change my mind and put it back in a pot on a shelf in the pond when the temps drop more. I didn't like the planter it was in (too bulky) and so I wanted to replant it anyway.

I might even change my mind about running the pond all winter and let it freeze this year. It scares me, because I really do not want to have to replace/repair a cracked preformed liner come spring.

I brought the creeping jenny, forgot-me-not, watercress, and frogbit inside. It's been below 30 already. I know the creeping jenny probably would have survived, but I decided to clean the middle waterfall tiers completely, including removing all the gravel and washing it, which meant pulling it, so I just brought it in. It never really did great in that spot, will try something different next year.

 

[TheFishGuy]

Got most of the algae pulled, left some on the deepest part of the pond, and got it all off the waterfall parts.

My problem is that my pond is heated in the winter so it doesn't freeze. The top tier of the waterfall will freeze solid, but the crowns of the plants can't be underwater up there. They either can go completely submerged under cold, but not frozen, water in the pond, or freeze solid with the crowns at the surface in the 4-5" deep gravel "pseudo-bog". I moved the chameleon plant up to the top tier with the marsh marigold (which never really did much), but I may change my mind and put it back in a pot on a shelf in the pond when the temps drop more. I didn't like the planter it was in (too bulky) and so I wanted to replant it anyway.

I might even change my mind about running the pond all winter and let it freeze this year. It scares me, because I really do not want to have to replace/repair a cracked preformed liner come spring.

I brought the creeping jenny, forgot-me-not, watercress, and frogbit inside. It's been below 30 already. I know the creeping jenny probably would have survived, but I decided to clean the middle waterfall tiers completely, including removing all the gravel and washing it, which meant pulling it, so I just brought it in. It never really did great in that spot, will try something different next year.

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it seems as if you could just turn the waterfall off, move everything into the main pond, and keep the pump running just as a fountian or "bubbler"

then you would reduce the risk of a cacked liner but be able to keep the main pond from freezing.