A good friend called and asked why 3 of her 5 Myrtus communis ‘Compacta’ died. I had suggested them, she had purchased them (in 5 gallon cans) from a reputable Berkeley nursery, and a local gardener had planted them about 2 months ago.
I didn’t know if I could tell what killed them, but was willing to go over and check them out: luckily they hadn’t pulled them out of the ground yet. What I found were shrubs planted about 4” too deep. The two that survived fortunately had been planted higher in the ground. Because the three were way too deeply planted, their bark was damaged and their roots couldn’t access the the oxygen they needed resulting in exposure to pests and disease that caused their demise.
I’m going to briefly outline what are now considered ‘best practices’ in planting shrubs, trees, perennials and annuals.
When preparing a hole for a new plant, it is essential not to dig a hole any deeper than the rootball of the new plant—if you do, the soil that you return to the hole will compact and the plant will sink too low.
It is good to dig the hole twice as wide as the rootball, when the plant is set in the hole, you can ‘backfill’ with the native soil.
Notice I did not say amend the soil slated for the hole: if you want to amend the soil, with some good compost, you should do it uniformly to the whole planting area. If you amend the soil in the planting hole only, it will encourage the roots to stay within the confines of the hole and discourages them from entering the surrounding native soil—you are essentially planting in a ‘container’ and the plant will be short lived.
After the hole is dug, if the ground is dry, I always fill the hole with water and let it drain before placing the plant in the hole. After placing the plant in the hole, and backfilling with about half the soil, you can water it in to settle the soil. Then finish backfilling. Water again to settle the rest of the soil. Do not use your foot to firm the soil because it can compact it and either damage or slow the root growth.
Mulch the area after planting: 2-3 inches of small fir bark, or, even better, compost, will help preserve soil moisture and will moderate soil temperature, keeping it warmer in the winter and cooler in the summer—the roots will appreciate that! Mulch also controls competing weeds and covers and protects the drip irritation tubing. It is essential not to pile up the mulch too close to the base of the plant, or you will have the same problem that started this conversation.
If my friend or her gardener had known these updated planting guidelines, those three myrtles most likely would be alive and an integral part of the row of five, forming a flourishing border to the garden.