The Latest Dirt - Nov 2023

Living in Wildfire Country: Unexpected Dangers in the Firewise Garden

Article and photos by Marilyn Saarni, Resilient Regenerative Firescaping Certified (Rescape, 2020)

Little lessons learned digging in the dirt. I’ve now converted about 75% of my garden to firewise landscaping. Along the way, I’ve been learning (through painful encounters) about unwise plant choices and maintenance details that require PPE (personal protection equipment—that phrase often characterizes the onset of COVID). I’m passing on some of these lessons here, hoping to save others from stabs, infections and frustration. And it saves you some money, too, as you can avoid adding these plants to your garden but then pay big bucks to remove them.

Plants with thorns. Honestly, don’t plant these anywhere you have to clear leaves and weed year-round. That is, nowhere in your Zone 0 (“Ignition Zone”) or 1 (“Lean and Green Zone”). And if you have a pine or fir tree—or your neighbors do—consider avoiding planting them anywhere in your entire defensible zone. Or, as I have strategized with my big climber roses, prune all the foliage in the lower four feet of branching, open up the framing, and have no groundcovers underneath. This way, you can rake around the thorny plants—the debris will blow through or fall on the ground. An additional strategy could be to mulch with cobble under stickery plants (if weeds are an issue, lay cardboard underneath the cobble—but keep 3-4 inches clear around the trunk of the plants).

You can then use an electric variable blower to help control flammable debris under these plants without risking an eye, getting stuck, or tearing another hole in your jacket or vest. As someone who maintains a 35-foot-long succulent bed, I also recommend no cactuses, thorny agaves, or aloes. Or if you want to keep them, consider putting them in large pots. The raised height reduces the amount of leaf debris that will collect in them (except pine and fir needles). The height also makes it easy to access. You’ll need long tweezers to maintain these plants. Another approach might be to plant them outside your defensible zone. Remember not to place these plants where they can endanger passersby (near sidewalks or paths) or get in the way of firefighters (by evacuation routes, driveways, or where they may need access to save structures).

Painful dead leaves to clean up. If you have prickly live oaks nearby, you’ll have to deal with their leaves. Suppose you have oak on your property. In that case, you probably already have a strategy to occasionally rake the leaves under the tree, preserving 1-2 inches of oak leaf debris to protect the oak soil microbe ecosystem underlying oak tree canopies. However, the oak leaves that catch one off guard will be embedded in the leaves you must hand-pick out of, say, a succulent bed or that you’re clearing by hand under salvia or other shrubby plants. The oak leaf takes a long time to decay, and I swear the prickles are the last bits to go. They can go through lighter-weight gloves, too.

Another culprit is the Mahonia genus. Wow, their thorny leaf tips are definitely the last to rot. I have long removed all the Mahonias—two deep punctures were enough for me. Some leaves don’t hurt your hands until they dry up. Two are the Arbutus unedo (Strawberry Tree) and Olea europaea (Olive). These leaves aren’t prickly while fresh and green, but as they dry, the Strawberry Tree leaves get sharp edges, and the Olive leaves curl lengthwise and develop a sharp tip. They are both fairly heavy litterers, and their leaves don’t tend to blow so far (unlike Pines, Firs or Oaks), so likely you’ll not run into these unless they’re in your garden or very close by.

An additional issue with the Strawberry Tree is that if you have a heavy bark-peeling variety, you’ll have to use your heaviest leather gloves to break off the loose strands that could catch embers—the bark peels can be as sharp as razors. Besides avoiding these trees in the garden, you could also clear a more expansive zone around them and surround them with large cobbles so that you can use a blower. Avoid planting areas nearby that require hand-picking of leaf debris (a succulent bed, for example).

Allergic reactions from sap. In this case, you need not eliminate these plants, but you might want to plant them in pots or be aware that you must wear gloves (maybe disposable) and glasses when working around them and dispose of cuttings and leaf debris to avoid exposure. Euphorbias are frequent perpetrators of rash reactions. Some aloes and agaves can cause burns (caustic sap); you may want to remove these. Indeed, they should not be in Zone 0 or 1. Where they are both thorny and caustic (e.g., Agave americana, aka century plant), they are not good choices for a firewise garden, where there is so much intense maintenance and increased chance of injury.

Protection. I always wear gloves now when clearing debris in the garden. For fine work (my succulent bed), I also wear my reading glasses to see the oak leaves before they bite me. And for my few gorgeous but toothy aloes, I use tweezers that are 12 inches long. For garden beds lined with rock mulch, I can use a blower to pile the leaves in a corner and then quickly pick them up with my heavier neoprene gloves, reducing skin contact to a minimum. I wear glasses whenever I use the blower; dust does kick up if I accidentally hit a small pocket of compost near the pebbles. Last, I carry a bucket everywhere I wander, so I never handle prickly leaves twice.

If you have any plants that have injured you, especially when you didn’t expect it, or tree leaves that have surprised you by cutting or puncturing you, please list the species or name in an email and send it to mesaarni@gmail.com. If you have come up with other ways to cope with prickles in the firewise garden, I’d love to hear about them. Send photos!