Sealing Barrels Flowers Struggling-Need Ideas

Hello! 

I need some help gardening peeps! 

I have 4 half barrels that I purchased specifically to grow flowers in. NO FOOD. I put treated posts in the center of all of them and concrete in the bottom. 
For 3 years I have tried to grow tons of different flowers in them, specifically climbing flowers to climb the posts. The growth in them is hit or miss. Some things grow fine and others never grow at all or sprout and then appear stunted. Same soil I use in all my raised beds with ZERO issues. Yes, it’s Mel’s mix. Some say its the posts, others say its the concrete in the bottom, others say its the barrels. I am in agreement…it is something. All I want is to grow some dang flowers. LOL. 

My idea is to empty the soil and get rid of it because I don’t want it getting into my food beds down the line somewhere. Then I was thinking of lining the inside with flex seal? The spray rubber? And sealing the inside, up the post and the concrete in the bottom, leaving my drainage holes at the bottom which have been more than sufficient. Add new soil and try again. 
Do we think this would work? More than anything I just want vining flowers to climb the posts and some flowers in the barrels. 

Thoughts? Better ideas? I really don’t want to scrap this whole idea…

THANKS IN ADVANCE! 

My best guess is that the drainage holes are plugged, resulting in the soil becoming saturated and depriving the plants of the oxygen they need. Are the holes drilled on the bottom, where they are in contact with the ground? Were the holes covered with a screen wire to prevent the soil from packing the hole full and blocking it? Have you tested the soil to determine the water levels?

When we water, the water comes out of the drainage. The wasps and bees frequent the drainage holes to drink. In the summer it is super hot and dry where I am even here in Idaho. So if I had saturated soil I would notice because everything else is so thirsty. I keep an eye on all of it really close. My backyard is my self care oasis, my place to decompress after work. So many nights I get out of my car after work and go straight to the backyard to look carefully at everything.

I put upside-down broken terra cotta planter pieces over the drainage holes of my containers.  Really helps.  Without seeing the planter, hard to say.  I love your set up!  You might try some battle-ax flower varieties, like Morning Glories, Cosmos, other things that grow well in your area.  I see you have nasturtiums, how do they do?  And sunflowers, again, pretty hard to mess with.

My mother in law put barrels on the edge of her patio to grow flowers and herbs in, and nothing thrived. They drained fine. What I realized eventually was that there was too much peat, the peat had dried at some point and never properly rehydrated, the water was draining before it could wet the peat. There was layering making for a mucky layer as well as too dry layer so plants could never spread their roots in good space. I added a lot of compost, some perlite and mixed really well. I was not successful at getting M-i-L to do deep slow watering, she loves standing there with her hose thinking green growing thoughts and that is a good thing in itself, even if not ideal for keeping peat moist. The petunias and zinnias grew huge and joyful.

So I am going to suggest redoing the soil and trying to specialize the mix for that situation. 

I hope you have success this year.

Like previous posts said, my first thought is drainage. Second thought is to get perennial hardy type of vining flower. I had a patio surrounded by potted and in-ground trumpet vines that grew up and over the pergola. It was beautiful for many years up until we moved. The ones planted in the ground did better than the ones planted in the pots, so maybe consider that aesthetic mixture for success…?

There's been some mention on the Foundation that perlite helps retain moisture even better than vermiculite. I wouldn't want it in my SFG beds (after 14 years, I'm still getting perlite floating to the top of the first beds I made with 50:50 coarse vermiculite and perlite). But, for flowers in containers, it may be helpful. The downside of perlite is that it doesn't have the electrical conductivity that vermiculite has so it's not recommended for our SFG beds.

sanderson wrote:There's been some mention on the Foundation that perlite helps retain moisture even better than vermiculite.  

Have they done a side by side comparison study? Everything I find in google searching says the opposite, that vermiculite layers physically expand with the absorption of water and thus holds more than perlites bumpy structure.  Floating up is a sign of not absorbing water but being a good air bubble.