September Watering and Mulching

Historically, September is a dry month in northern NM. The angle of the sun in the sky this month seems to magnify its heat and intensity. So it’s essential to water this season’s transplanted perennials, shrubs and trees regularly and deeply. One to two times per week and moisten the soil down about 12”. Be sure to replenish the mulch around the base of your plants. A 1" - 2” thick layer of mulch is optimum and keeps the soil cooler and moister. Replenish the mulch under established plants and provide them with good watering every 10-14 days.

Watering New Transplants: Even xeric (waterwise plants) need regular watering during the first growing season to grow strong, deep roots. Don’t water stress new plantings by not watering enough!!

BY WATERING DEEPLY AND FREQUENTLY THROUGHOUT THE SUMMER, you’ll save water in the long run as the plants will establish more quickly and require less frequent watering during the following growing seasons.

• At this point (early September), your transplants will need watering every 3-4 days.

• Water twice: fill the saucer to near overflowing, let it percolate into the soil, and fill the saucer again.

• Of equal importance, is making sure all your plants have been mulched, especially your new transplants.

Make a Water Holding Saucer and Mulch It: When watering new transplants by hand, be sure the plants have a nice, wide, one-inch deep saucer-shaped depression around their base to hold water. If you planted in spring, the water saucers may have become shallow filling in with soil. Reform the saucers making them wider and deeper so they will hold more water.

After checking and reforming the water saucers as needed, I recommend that you fill the depression with mulch to keep the soil cool and damp. (Yes, I fill the saucer-shaped depression with mulch. This helps the saucer hold its shape after repeated waterings.)

Mulching New Transplants: Use mulch materials like crushed gravel, Back to Earth Cottonburr Compost, pine needles, or finely shredded bark. Mulching reduces transplanting stress by keeping the soil more evenly cool and moist. Perennial plants should be mulched to a depth of one inch directly under and around so as to cover a wide ring of any bare soil around them. Woody plants (trees, shrubs, and evergreens), the mulch layer should be 2 to 3 inches deep. fill the saucer to near overflowing, let it percolate into the soil, and fill the saucer again. When watering by hand, be sure the plants have a nice, wide, one-inch deep saucer-shaped depression around their base to hold water. I also filled the depression with mulch to keep the soil cool and damp. (Yes, I fill the saucer-shaped depression with mulch to help it hold its shape after repeated waterings.)

Mulching Established Plants: Be sure that all your established perennials, trees, and shrubs are well mulched with a thick layer of wood chips, bark chips, crushed pecan shells or pine needles placed in a wide circle around their base. Now is an excellent time to thicken up the mulch layer as the mulch decomposes into the soil and becomes thinner. Even gravel mulch gets thinner after the freeze/thaw cycle of winter and spring absorbs the gravel into the soil.

Perennial beds need a one-inch layer of mulch material.

Trees and shrubs need a 2 to 3 inch layer of mulch material.

Irrigating Established Plants and Landscapes: It’s much better to water less frequently and deeply with more water than more frequently with less water. Roots follow the water down into the soil. Ample deep watering increases root depth and resistance to dry conditions above ground. You can train your garden to be more water-thrifty by doing it this way. In the heat of summer here in arid New Mexico, I water once every 7 days watering long enough that the water goes 8 to 12″ deep into the soil. Trees and shrubs need a 2 to 3-inch layer of mulch material. Plants on a Drip System: If your plants are being watered on a drip system, and you have new transplants on the same watering zone as established ones, you'll need to program your irrigation controller using two schedules. One schedule should turn for at least 1 ½ hrs. once or twice per week. Then program a second schedule to come on every other day for 30 minutes to keep your new transplants adequately moist.

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