Pruning California Native Plants

Various California native plants benefit from periodic pruning to rejuvenate, improve their look, or to maintain their health. In this blog post we will discuss pruning regimens for some of the most common California native plants. This guide is for gardeners that live in California or a similar Mediterranean climate. California Natives grown in temperate climates will have similar pruning needs, but the timing will not be the same as in a Mediterranean climate.

Pruning Tools

Before you start pruning, make sure you have the right equipment. The best set of tools for hand-pruning are:

• Bypass Pruning Shears
• Pruning Snips (also known as straight blade pruners)
• Lopping Shears
• Pruning Saw
• Pole Saw (if you need to prune tall trees/shrubs)

In addition to these tools, you should ensure your pruning tools' cutting edge is kept sharp and clean. This will ensure that you get clean cuts and prevent cross-contamination if any plants are diseased. To that end, the following should also be kept on hand during pruning:

• Blade Sharpener
• Disinfectant (Rubbing Alcohol or specialist product such as Citrox or Physan)
• Rag for wiping the blades on pruning tools.

Power Tools

Pruning can be done with chainsaws, hedge trimmers or reciprocating saws but its much harder to make clean cuts with these power tools unless you are experienced. Until you are familiar with the pruning needs in your garden, stick to hand tools for now.

Pruning Times

As with most plants and not just California natives, the main time to prune is when they are dormant, before new growth starts. In addition to Winter dormancy, many California natives go dormant in late Summer. Some plants will also benefit from light pruning in Spring to prolong their blooming periods. For the most part, you should not be pruning on a regular basis. If plants are growing in to each other, it may be better to remove some to space everything out more naturally, rather than continuously cutting them back.

Winter Deciduous Plants

Any shrub or tree that loses its leaves in winter is ready to prune during this period of dormancy. Common species that fall into this group are: Engelmann oak (Quercus engelmannii), Dogwood (Cornus spp.), Elderberry (Sambucus spp.), Desert Willlow (Chilopsis linearis), Currants/Gooseberries (Ribes spp.), native Grapes (Vitis spp.).

After their leaves have fallen, these woody shrubs and trees can be more easily inspected for structural problems such as dead wood or crisscrossing branches. Root suckers should also be removed at this time. The goal here is to address these issues and open up the structure of the plant to reduce crowding and improve airflow. Please note that Ribes species will typically fruit on growth that is 2 years old, so pruning older growth can affect your fruit yield.

Herbaceous Perennials

Most herbaceous perennials benefit from two types of pruning: deadheading after flowering, and cutting down to rejuvenate in late Summer or Fall. Deadheading is a technique where the spent flower heads are removed from the stem to encourage successive blooms to prolong the flowering season. Plants naturally want to complete their reproduction cycles and if prevented from going to seed, they can produce more flowers. Cutting the shrub down close to the ground will promote new more vigorous growth and prevent legginess. Common species that fall into this group are: Pitcher Sage (Lepechinia fragrans), California Poppy (Eschscholzia californica), Columbine (Aquilegia spp.), Lupines, Penstemons, Desert Mallow (Sphaeralcea ambigua) and Zauschneria (Epilobium canum).

Woody Perennials

For this group of plants, the pruning needs are various and there is no simple rule to apply to all. For some of the most common species, here are the suggested pruning regimens:

Salvias

All Salvias benefit from deadheading after their flowers are spent. "Bushy" Salvias like Cleveland Sage or Purple Sage should be trimmed back no more than 1/3 of the plant to shape the plant and remain vigorous. Avoid cutting back old growth on Salvias as these often do not resprout foliage. The main pruning should be done in Fall.

Toyon

Toyon (Heteromeles arbutifolia) can be hard pruned in Winter to remove dead wood or trimmed up to form a tree. Toyon is pretty tolerant of pruning and can handle cuts throughout the year, however the flowers and berry growth is less affected when pruned in Winter. As a chaparral plant, they are well adapted to wildfires and can regrow even when burned down to a stump. For this reason, they take well to coppicing, which is when the shrub is completely cut to the ground. After coppicing , the shrub will grow more vigorously and take a more bushy shape, so this is a good solution for when the shrub gets too leggy. Coppicing too frequently can kill the plant, so this should not be done every year.

Buckwheat

The jury is out on whether Buckwheat (Eriogonum spp.) can be hard pruned. Some say it could kill it, but city maintenance workers keep severely cutting these back at my local park and they always bounce back. Nonetheless, they do benefit greatly from deadheading in fall/winter when their flower heads are completely dried out, as some can remain on the plant into the next growing season. While you are doing this, inspect for brown leaves and remove this dead wood you find in the shrub

Manzanita

Manzanita (Arctostaphylos spp.) does not respond well to pruning as they do not resprout from old growth. In Summer, after they are done flowering, you should inspect the plant and remove branches only for health reasons.

General Tips

• Always clean and disinfect your pruning tools when your are done pruning a plant and move on to another plant. This prevents cross-contamination of plant diseases.
• Try to do pruning when the weather is dry and no rain is in the forecast for a few days. Open cuts are more susceptible to infection when wet.
• Keep your cutting blades sharp. Make it a habit to sharpen them after each day of pruning.
• Plan your pruning before you start. Don't start hacking away without first deciding what effect you want the pruning to have.
• For large trees, hire a certified arborist.