Whenever I see Woolly Bluecurls (Trichostema lanatum) at a native plant nursery, I’m tempted to stop and say a little prayer for the poor things. With their sapphire flowers and ineffable, resinous fragrance, they seem so poignantly naive about the world outside their utopian bubble of plastic pots, perlite and shade cloth. As a breeze passes through, I imagine them trembling with excitement as they await that auspicious day when they will be taken home, lovingly planted – and killed.
Sad, but true. Despite its popularity, Woolly Bluecurls is a notoriously short-lived plant in the garden. There is, in fact, a certain, well-known California native plant compendium that goes so far as to flatly advise that Woolly Bluecurls – a perennial – should be treated as if it were an annual, given how maddeningly difficult it can be to keep it alive for more than one season.
And while it may not be a bad idea to adjust your expectations downward when it comes to planting Woolly Bluecurls in your garden, I am here to tell you that you don’t necessarily have to resign yourself to watching helplessly as it withers and dies each summer after an all-too-brief flowering. There are, in fact, several fairly mature Woolly Bluecurls in the LANPS garden, the oldest of which are now about five years old. While this may be the result of nothing more than dumb luck, I like to attribute it to the following five “rules,” gleaned from various sources and put to the test in my own garden for over a decade.
HOW NOT TO KILL WOOLLY BLUECURLS
RULE NUMBER 1 – Plant Early and Water Deeply
You may have heard that Woolly Bluecurls dislikes summer water, but take it from me – that is absolutely not true.
It fucking hates summer water.
With this in mind, it’s essential to take full advantage of the cooler soil temperatures of the fall and winter months to establish your new Woolly Bluecurls with as deep a set of roots as possible. Deeper roots are better insulated against the higher soil temperatures that come with summer heat, making it more likely that the plant will survive its first summer in the ground.
So, as soon as the weather has seasonally cooled and the chance of rain is at least a theoretical possibility, get your Woolly Bluecurls in the ground and start watering it like you would any other newly planted native species. It will likely respond with lush new growth and maybe even a flower or two.
But the timing isn’t the whole story. The point here is to get the roots to penetrate your native soil both quickly and deeply. In order for that to happen, you need to water deeply, thereby luring the roots downward. Based on sage advice I got from a botanist at California Botanic Garden many years ago, I try to water to a depth of around 16 inches below the soil surface. At that depth, or so the thinking goes, the roots will stay cool throughout the hottest days of summer. A good way to make sure you’re watering that deeply is to use a simple soil moisture meter.
RULE NUMBER 2 – Plant on a Slope in Full to Part Sun
Outside of species that are adapted to riparian corridors or wetlands – most plants, including California natives, don’t appreciate having their roots sitting in water. But while other, less persnickety species might struggle with soggy roots, for Woolly Bluecurls, such a condition is the equivalent of a death sentence. If your garden has fast draining, granitic or sandy soil, you’ll definitely have an easier time of it keeping your Woolly Bluecurls alive. (Full disclosure: most of the soil in the LANPS garden fits this description.) If you’re trying to plant it in heavier, slower-draining clay soil, getting it to last is going to be a little trickier.
But no matter what kind of soil you have to work with, you can improve your Woolly Bluecurls’ chances of survival by siting it on a slope, where the force of gravity tends to turbocharge drainage. In fact, on those rare occasions when I’ve encountered Woolly Bluecurls in the wild, it has always been on a fairly steep, west or southwest-facing cliff.
In other words, you’re trying to replicate, as much as possible, the conditions that support the plant in its ideal native habitat: extremely lean, even rocky soil; gravity-enhanced drainage; and a blast of afternoon sun. (In the hottest inland locations, a little afternoon shade won’t hurt.) If your garden doesn’t include a west or south-facing slope, choose the sunniest spot you have and create your own slope by piling up soil and rocks into a small hillock. Don’t forget to plan for some kind watering basin with a berm on the downslope side when you dig the planting hole.
RULE NUMBER 3 – Use Mineral Mulch
Like many of its fellow chaparral species, Wooly Bluecurls will benefit from a layer of mulch to keep its roots cool in summer. But not just any mulch. Woolly Bluecurls doesn’t appear to like typical, plant-based (“organic”) mulch, which, under certain circumstances, can cause root rot, especially if the mulch is piled up around the crown. Plant-based mulch also breaks down over time, enriching the soil with organic matter as it does. Some native plants might appreciate that, but Wooly Bluecurls isn’t one of them.
Here in the LANPS garden, we line the watering basin of each Woolly Bluecurls with a layer of mineral mulch – small to medium granite rocks – leaving just a small circumference of exposed soil around the base of the plant. Remember, you’re trying to simulate a rocky, west or southwest-facing cliff. If you give your Woolly Bluecurls the sometimes brutal heat of that exposure without providing the cooling, protective effect of plenty of rocks in the surrounding soil, the roots can literally bake to death.
RULE NUMBER 4 – Withhold All Summer Water, Even in the First Year
Let’s just call watering Woolly Bluecurls during the summer what it is: the kiss of death.
More than just about any other California native plant, Woolly Bluecurls requires of its guardians an iron-willed, summer dormancy machismo. And, as transgressive as it might seem, this means absolutely not one drop of water after April or May, even during the plants’ first summer in the ground.
Admittedly, without any supplemental water, Woolly Bluecurls will get to look pretty bedraggled as the summer wears on. The spent flowering stalks will be crusty and brown; a lot of its leaves will have dropped and those that do manage to hang on will be seriously desiccated. You may even start to imagine the drought-stressed plant piteously crying out to you for water, but you have to stop, pull yourself together and hold firm. Like the story of Orpheus and Eurydice, unless you’re willing to risk killing the thing you love with kindness, you just can’t give in.
Needless to say, a successful application of Rule Number 4 (“Withhold All Summer Water, Even in the First Year”) requires an adherence to Rule Number 1 (“Plant Early and Water Deeply”). If you haven’t given your new Woolly Bluecurls enough time out of its pot to develop the deepest roots possible, it will be less likely to survive its first summer without any supplemental water.
RULE NUMBER 5 – Hand Water
Given Woolly Bluecurls’ distinct need for absolutely dry soil during the summer months, isolated hand-watering is definitely best. If you plug Wooly Bluecurls into a garden-wide irrigation system set up to support more forgiving species like Toyon (Heteromeles arbutifolium) or Black Sage (Salvia mellifera), it will necessarily suffer.
Given that you’re probably accustomed to watering California native plants through their first few summers in the ground, this approach might feel intolerably risky, but if you’re already a Woolly Bluecurls serial killer, what have you got to lose? After all, if your plants haven’t been surviving the summer with water, the worst that can possibly happen is that they won’t survive without water.
One final caveat: please don’t make the mistake of assuming that the highly individual cultural needs of Woolly Bluecurls apply to all California native plants. The fact that a particular species can’t tolerate summer water doesn’t mean that all native species are equally touchy. In my experience, most aren’t.