u/Shu-sh

I feel like I’ve probably done something fundamentally wrong here. We have been gardening in Denver for the last six years and recently moved. Before this, we did all inground planting with drip irrigation on each plant and did pretty well each year. I think peppers are generally pretty hard here just because of the length of the growing season, but as far as zucchini, eggplant, and tomatoes, we’ve always done pretty well, with our tomato plants usually reaching 11 feet tall on a trellis.

Long story short, we moved to a new place with much less yard space, and the area we do have is mostly cemented. We thought buying above-ground planter boxes would let us get something going quickly before the growing season started. I found some that were 12 inches deep by 20 inches wide by 4 feet long. We put a bit of mulch at the bottom and then filled all of them with planter box soil.

The seedlings started out great indoors. We planted them outside once some were already pretty large, but all of them completely stalled and didn't really grow after that. For context, they get direct sun from around noon until maybe 6 PM. We didn’t irrigate them with direct individual drips this time; instead, we used snaked emitters and covered them with mulch to try to retain moisture, figuring these boxes would act like clay pots, heat up, and lose water quickly.

We’re super disappointed that our yields were awful this year. On the other side next to them, we had a very small amount of inground space where we planted normally, and the tomato plant there is huge while the zucchini is currently 3 feet tall by 5 feet wide. So it’s gotta be something with the planter box setup, right? Any sage-like advice from longer-term gardeners is greatly appreciated. Thanks!