Ask Mr. Smarty Plants

No, the salvia did not kill the other plants. The real news here is that the salvia survived. We all see pictures of plants growing in wheelbarrows, especially in "country" gardens, which is a misnomer, because in the real country wheelbarrows are used to haul stuff, not as planters. What you created is basically a container garden. We would like to say the salvia survived because it is native, but all of the plants you listed are either non-native or extensively hybridized, so we can't get away with that. Please read our How-To Article on Container Gardening with Native Plants.

Since we obviously don't know the whole story, we will offer some conjectures on what went wrong. The first thing that comes to mind is that of poor drainage. Very few plants, except water plants, can survive long with poor drainage. Water or very soggy soil on the roots will kill the plants fairly quickly. Just guessing, but perhaps the salvia were in the "uphill" side of the wheelbarrow and the surplus water drained down, and was trapped there, around the roots of the other plants. So, if you did not drill drainage holes in the wheelbarrow before you put the potting soil in it, that could be the scenario.

The second thought has to do with location, location, location. Was the wheelbarrow in a sunny or shady spot? We consider sun to be 6 hours or more of sun daily, part shade 2 to 6 hours of sun, and shade 2 hours or less of sun. Since we have only salvia in our Native Plant Database, and just guessing that your hybrids would have followed the norm, we chose to look in our Native Plant Database at Salvia coccinea (Scarlet sage), which is native to Florida. According to the information on the page devoted to that plant, it has medium water usage, can grow in sun, part shade or shade. So, that plant was already prepared to grow in whatever sunlight was available, but we don't know about the other plants.

Another possibility is that the wheelbarrow might have materials already in it that could be contaminating to the plants. For instance, we always used our (metal) wheelbarrow to mix concrete in small batches. When we moved away a lady bought that wheelbarrow at our garage sale to put plants in. We did warn her that it had been used for concrete mix, and she assured us that was okay, she was going to plant in it. Of course, we never heard the outcome, but there are components of concrete that could damage plant roots as it seeped up into the soil.

And finally, plants die, and Mr. Smarty Plants can only wonder why. Perhaps they had already been damaged or become pot bound before you ever purchased them. Maybe they couldn't take the temperatures in which they were placed, or they may have been annuals that bloom, set seed and die, all in a period of a few weeks sometimes. If you are determined to go the wheelbarrow route, we would suggest you plant in individual terracotta pots, which will solve your drainage problem IF you drill holes in the wheelbarrow. Plant roots can rot just as well in water standing outside the container as inside.