Planting and Maintaining the Beds
After preparing the beds and amending the soil, add underground irrigation, if that is in your plans.
Level the bed with a landscape rake or form your mounds to create added micro-niches. Add rock of varying sizes for accent. One important design consideration to remember is to keep your rock type uniform. One exception is in the case of a dry riverbed. Using river rock to mimic nature will work with larger accent sandstone or moss rocks.
For xeric beds, pay attention to the amount of space between plants. If you don’t plan on supplemental irrigation of the bed and will let the plants rely on available moisture, space the plants further apart. All xeric plants require water. Even though you’ve amended the beds, if you pack the bed full of plants, only the strongest will survive without supplemental irrigation—the soil will only hold enough moisture for a few plants.
Place your plants carefully, either grouping together certain plants for the massing effect and scattering others for diversity. Taller plants are normally placed to the back and the low, mounding and plants of interesting foliage in the front. A handful of Yum-Yum Mix can be added to the bottom of the plant's hole. The larger the container size of the plant, the more Yum-Yum mix you should use. Yum-Yum Mix (made by Soil Mender™ Products from Tulia, Texas) is an excellent additive that boosts the soil's health by stimulating the soil microbes, thus making available needed nutrients for the plants. Yum-Yum Mix includes alfalfa meal, cottonseed meal, kelp meal, green sand, rock dust and soft rock phosphate. Use Yum-Yum Mix, or a similar mix, with any new plantings. I've used it in all my plantings of the last 15 years and have had great success in plant survival.
Mulching Xeric Beds
Lay above-ground drip irrigation (if part of the plan) before the mulch. Lastly, lay stone or gravel mulch. Very carefully, by hand and shovel, place a 1 1/2 -3" layer of the stones or gravel around the plants and over the entire bed. Crushed granite, gravel or small river stones 1 1/4 inch in diameter would be used for the mulch. Xeric and alpine rock garden plants are used to an austere and severe existence. If treated to moist and decaying mulch, root rot could develop.
Establishing the Plants
Water the plants in and monitor their watering, particularly during the first month of life in their new home. First, water everyday, then 2 - 3 days, then twice a week, then every other week, if the weather is hot, a little less frequent if it is cool (80 degrees or less). How long you continue each stage depends on your soil and weather. But by summer, watering will become more infrequent even though it's hotter, and next year, even less so. One deep watering a month should be all that's needed for established low water-use plants, either by your watering system or by rain under average weather conditions. Country locations, where conditions are more extreme, may require more frequent watering because of windier conditions. Watch your plants and gauge your watering carefully. I cannot, with certainty, tell you how much water is required. Microenvironments vary greatly. In my experience, plants establish very quickly in beds with a thriving beneficial soil life community.
Maintenance of xeric beds is minimal. By summer, many plants will double in size and begin to flower. Some may not flower until next year. When the soil is properly prepared for a low water-use bed, no additional fertilizing is needed. The plants will thrive on the slow release nutrients the compost provides. Applying high nitrogen fertilizers is harmful by causing too rapid a growth in xerophitic plants and in harming the soil organisms. The rapid formation of woody fibers won't properly form, causing the plant to stress or die under extremes of temperature (rapid temperature shifts) or drought. Rapid growth also changes the appearance of the plants from the neat compact plants we expect to rangy overgrown plants that give you the urge to prune back.
Weed the beds often to keep them under control. Spring cleanup is easy with just light raking or snipping. These plants require very little attention, except for appreciation.
If a decline in vigor is noticed in following years, pull back the rock mulch and apply a half inch to inch layer of fine compost or soil amendment with trace minerals and high quality compost blend. The rock mulch will need to be replenished some yearly, as the rocks will work their way down into the soil. A simpler method to boost your plants during the stress of summer would be to water with compost tea or a liquid organic fertilizer such as horticultural blackstrap molasses and/or a seaweed or fish emulsion product.