Elinor Teague on Gardening: Digging out invasive intruders

Last year, the soil in my drought-tolerant garden was baked so dry and hard by the drought that it was impossible to get a shovel or spading fork into areas not irrigated by the drip system. This winter’s early rains have softened the soil so that I can begin to dig out unwelcome plants, transplant others into better spots and replace several dead plants.

The unwelcome plants are huge clumps of Mexican feather grass (Nasella or Stipa tenuissima), an extremely invasive species. Mexican feather grass produces copious amounts of small, lightweight seeds that are easily blown throughout the neighborhood and carried on shoes, tools, animal fur and lawn mowers. The primary goal while removing the grass is to limit the amount of seeds that fall during the process. Placing as much of the grass clumps as possible inside large plastic leaf bags before attempting to dig them out is a good first step. Digging the clumps out slowly and gently and then placing the plastic-covered clumps inside another bag is a good second step. No blowers for final cleanup – just rakes and brooms.

Several yarrow plants will be moved to a spot near the kangaroo paws. The sharp edges of a spade or shovel cut through plant roots, delaying the establishment of the transplants’ root systems in the new spot. I much prefer to use a spading fork for transplanting. The fork tines slip between the roots, causing less damage, and the fork can be rocked back and forth to loosen the soil, making it easier to lift the intact rootball out of the hole. I’ll also use the spading fork to move the sparaxis bulbs into a more visible location and to lift and separate the overcrowded narcissus after spring bloom.

The prostrate ceanothus all died last year. Ceanothus, also known as California lilac, blooms heavily in spring, attracting bees and other pollinators. I’m going to experiment with replacing the ceanothus with flowering verbena – also drought-tolerant – and it has a longer bloom period.

The soil in my garden is mostly clay, which is why it dried out so hard during the drought. After digging a new planting hole, twice as wide as the rootball of either a transplant or a new container plant but no deeper, the native soil will be mixed half and half with a good quality soil amendment. I maintain a kitchen waste compost pile and a bucketful of the compost will also be added to the native soil for each transplant. Before planting, the hole will be filled with water and allowed to drain.

The transplant will be set in the hole, the hole will be half filled with the newly amended soil, watered again and then filled with soil. The transplants will be set an inch or two higher than the surrounding soil, since the soil will settle in the hole. A gentle tap with a boot to firm the soil around the plant, one more watering, and then we monitor for signs of new growth in a couple of weeks, as temperatures begin to warm in our early spring.

This story was originally published January 4, 2016 at 3:36 PM with the headline "Elinor Teague on Gardening: Digging out invasive intruders."