Planting on a Hill or Berm - Watchouts and Recommendations
If you plan to plant anything on a hill or a berm, here are some watchouts and recommendations.
If the hill or berm is new (recently built up) it will likely be dry as can be from top to bottom. Any water you spray onto it will be quickly soaked up and percolate through the soil like nothing ever happened. This has been the case for our hill and berms. They were built using the spoil from scraping the old compacted pasture turf, some rock and gravel from around the property, native topsoil, and several truckloads of purchased topsoil.
With this in mind, especially if you live in an area that is very hot and has little rainfall during the summer, you're going to have to water much more than you would expect to until the plants are well rooted after a few seasons (and maybe even longer).
If at all possible, you may want to consider installing permanent drip irrigation directly to each plant's root system. It's an efficient, focused way to water and should decrease runoff.
Depending on your hill's soil and how much rain you get throughout the year, you may find that planting in a bit of a depression will help to capture and retain the water rather than having much of it simply run down the hill. This can sometimes be problematic if you're planting "on the flat" or if you have heavy clay soil that retains moisture. You can also build up a small soil dam on the downslope edge of the hole to help retain the water in the plant's root zone.
Keep an eye on the soil moisture in the plant's root zone and immediate area. Use a moisture meter and/or use your finger. You'll be able to spot any problems before your plant shrivels up.
Sometimes the top ~2-3" of soil may dry out fairly quickly but there is a layer of soil (or something else) just below the plant that doesn't allow water to pass through very well. It's possible that a lower portion of the plant root ball could end up sitting in very soggy soil that you can't easily detect. This can be as much of an issue as being too dry. Depending on the size of the plant and depth of the root ball, a moisture meter can help you read at lower depths.
If you find that your sprinklers or the rainfall you get isn't enough, you may need to drag a hose over to each plant and give it a deep watering once per week. It could be twice per week depending on your soil and conditions. It will be more effective than just running your sprinklers longer.
You can mix some compost into the soil you backfill with in the planting hole. Not only are you adding organic material that is beneficial to soil health and structure, it also helps to retain moisture around the root zone. It is a balance though depending on the plant’s position and the soil it is planted into. You can also end up creating a sump that retains too much moisture and starts to affect the plant (although, in practice, I have seen this happen fairly infrequently).
Weedy Pete
