Tip of the Week: How to Be Water-wise When Planting

Posted in Gardening Tips on August 9 2010, by Sonia Uyterhoeven

Sonia Uyterhoeven is Gardener for Public Education. Join her each weekend for home gardening demonstrations on a variety of topics in the Home Gardening Center.

While it is edifying to talk about ways to reduce the need for supplemental irrigation as I did last week in my blog post that explored drought-tolerant plants, it is all water under the bridge if the beautiful xeric garden that is planted isn’t properly maintained.

Here are some tips to get you going in the right direction. Many of the suggestions are common sense, but I am generally so anxious to get the plants in the ground and to watch them start growing, that I often need these reminders myself.

1. Plan your garden by grouping plants with similar cultural requirements. Place drought-loving plants together to create a low-watering zone.
2. Site your plants carefully. Drought-tolerant plants will either flop or die in soils that are too rich, have inadequate drainage, or are heavily fertilized. For many Mediterranean plants, it is not the cold but the combination of the wet, water-logged soil with the cold that kills them in winter. Good drainage is important for drought-tolerant plants.
3. If you have heavy soil, amend it with organic matter such as compost, grit, or pea gravel to improve drainage. If amending the soil will not do the trick, consider either relocating the plants or building a raised bed to improve drainage.
4. Substitute groundcovers in areas where it is difficult to grow turf such as in particularly shady areas or narrow sections of your yard. Some good perennials for dry shade are barrenwort (Epimedium), dead-nettle (Lamium), foamflower (Tiarella), hellebore (Helleborus, pictured), and big root geranium (Geranium macrorrhizum).
5. Space plants properly so that they do not compete with each other for root space, water, or nutrients. Plants generally fill in quickly, and it is better to have good spacing so that you are not faced with overcrowding and all the cultural problems that come with it.
6. Water wisely. Water early in the morning before the heat of the day to minimize evaporation. Allow nature to do its share: You do not need to water your garden after a heavy rain. Watering by hand at the base of plants, with soaker hoses or with drip irrigation, is highly efficient. Oscillating sprinklers tend to be less efficient but can be used early in the day.
7. Water deeply and less frequently for more efficient root systems. Do not water unless your plants need it. To check, stick your trowel 4–6 inches into the ground to see if the soil is moist. The rule of thumb is 1 inch per week (approximately ½ gallon per square foot).
8. Mulch your garden not only to suppress weeds but also to retain moisture. A 2- to 3-inch layer of mulch is more than sufficient for most areas of your garden. Shredded pine bark, shredded leaves, and fine gravel are three options that provide very different looks.
9. Weed your garden frequently in the spring. Rather than trying to tackle everything at once, spend 15–30 minutes weeding several times a week. As well as getting the job done, you will be spared unnecessary back pain and exhaustion. Weeds compete with plants for water and nutrients.
10. Most plants take 1–2 years to establish a good root system. During the first year, water conscientiously. Once the plants are established, consider your soil conditions (e.g., clay, loam, or sandy soil) as well as the temperature and age of the plant when deciding when to water. Remember that even drought-tolerant plants need help getting established.
11. Do not fertilize water-stressed plants. The salts in the fertilizer will burn the weakened, water-deprived roots.
12. Use water-retaining polymers (e.g., Terra-Sorb™ or Soil Moist™) in your container plantings to absorb and hold water.
13. Finally, some of your plants may start to wilt in the heat of the day. This does not necessarily mean they need water. It is a normal defense reaction to high temperatures. If the same plant is wilting in the morning, then it is suffering from water stress. Always check the soil for moisture levels. Keep a watchful eye on newly installed plants as they are more vulnerable because their root system has yet to be established.