Xeric plants looking bad

Asked October 14, 2020, 11:29 AM EDT

Hello, I have a number of xeric plants that I got through the garden in a box program that are a couple of years old now. This year they have been looking terrible and I can’t figure out what’s going on. I was watering them once/week and tried more often and less often with little change. The only thing that changed was a new sprinkler - I started using an overhead oscillating sprinkler to cover more area. It did seem like I had to increase the time it ran in order to get enough water to soak in past the surface. Are they dying? Thanks!

Denver County Colorado

5 Responses

'Xeriscape' suggests plants that will live on less water than turf grass but it doesn't always mean plants that will thrive in the sort of hot, dry conditions we had this summer. That said, it is hard to say at this point what happened. Try watering more frequently - like twice a week instead of once. Also keep in mind that we had a freeze in early September. Although plants in Denver fared surprisingly well, it may have discolored the foliage or shut down growth on some of your perennials.

I recommend that next season you set out shallow containers throughout the garden, run your sprinkler as usual, then measure how much water is in each container. You may discover that you are supplying more or less than you realize or possibly that it is being delivered unevenly so that some plants are getting more than others. Another good idea is to stick a screwdriver into the soil at the base of the plants - if it slides in easily, you probably are supplying enough water; if it is hard to push in, you probably are underwatering.

Thank you! Do you know or can you point me to a good resource for information on how many inches/week xeric plants should get each week?

Unfortunately, there isn't one ready resource because there are too many variables. In addition to the species water will vary based on whether a plant is new or established, the exposure (east, west, south, north), hours of daylight, soils (from quick-draining sand to poor-draining clay and everything in between), competition from surrounding plants, degree of mulch, temperature, precipitation, season, etc.

That said, start with approximately 1" per week (including natural precipitation) adjusted for site conditions for new perennials; as the plants establish, you can dial back gradually to less and watch how they fare. How low you go depends on the plants, the conditions, and the weather; you have to experiment to figure out what works best for your plants. Here are a few resources to help you:

https://extension.colostate.edu/topic-areas/yard-garden/watering-a-home-landscape-during-drought-7-2...

https://planttalk.colostate.edu/topics/annuals-perennials/

Great- thank you!

Great- thank you!