Burned, boiled, scraped with a rasp, doused in acid, or left alone? What’s the best way to germinate manzanita seeds?
The first manzanita seedlings
I’d begun a little
kitchen experiment over two months ago to see which technique would give the best germination for the Mexican (or pointleaf) manzanita,
Actostaphylos pungens. As of a couple days ago, the winner is: scraped with a rasp.
Here are the first two tiny seedlings that breached their seed coats and made it up to daylight. I’d filed down through into the hard seed coat on the seeds of this batch, letting moisture reach the embryo inside, and to make it easier for the new plant to emerge. (In gardener-speak the process is called “scarification.”)
I’ll post more results as the other seedlings emerge. If they ever emerge. This is not one of those instant gratification, buy-it-at-the-home-store-and-stick-it-in-the-ground experiments…
December 20 2008 | Categories: gardening • my garden | Tags: Add new tag • Mexican manzanita • pointleaf manzanita • seedlings • seeds | 7 Comments »
The pointleaf manzanita seeds I ordered ended up being from one of the many plant species (not only manzanitas) that depend on fire to perpetuate their species. In nature, a brisk fire might wipe out many of the existing plants, but the fire also creates an opportunity for the seedbank to come to life. Without the necessary fire, the seeds just lie on the ground–that’s if they don’t get eaten by critters.
The subjects in this experiment exhibit really really hard shells that protect the embryo inside. Getting word from a hospitable outside world to the swaddled seed germ is the challenge. The seed packet I received recommended soaking them in sulfuric acid for six to fifteen hours. That’s one way to break through the seed coat to get moisture and nutrients inside.
Doing research on similar manzanitas, some sites recommended scratching the seed coat, making sure not to damage the germ inside. Some papers recommended building a four-inch pile of combustibles above the seeds and setting the pile on fire. And yet another recommendation was to boil the seeds for fifteen to thirty seconds (one source) or one to two minutes (another source).
No matter which of the above methods was tried, the seeds also required cold-stratification to convince them that they had endured a near-freezing winter and could begin growth. Which seed-torture method to try was the question.
Sulfuric acid: Where can a non-chemist get it easily? And it sounded a tad dangerous.
Scratching the seed coat (sometimes called scarification): Tedious for more than a couple seeds, and how could I be sure I didn’t scratch off too much? Or not enough?
Building a fire over the seeds? This method also sounded dangerous, but potentially fun.
Boiling the seeds (a variant on scarifying seeds): Sounded safer than acid or fire, but do you go for fifteen seconds or two minutes? Wouldn’t too long kill off the little embryos?
I think that temperamentally I’m part mad scientist. I thought an experiment to test out all the recommended methods might be instructive–and at least a little entertaining.
Acid bottle
Sulfuric acid soak
I found some weak sulfuric acid in a little squeeze bottle at a pool supply store. At a concentration of less than 1%, it was meant for testing water, not for playing with the acid balance. Pretty weak excuse for acid, but worth a try. I soaked some seeds for 18 hours overnight, adding a little time to the end because the stuff was so dilute. (A day after doing this I encountered an old bottle of drain cleaner in the garage, something labeled sulfuric acid. I’ll try another soak with the
real stuff later on.)
Scratching the seed coat
The next method was to scratch the seed coat. I used a steel file to break the seed coat and a pair of pliers to hold the seed. I scraped varying amounts off the seed coat, from a moderate amount to a fairly aggressive amount. This was hard, slow, delicate work–way more difficult than I thought it would be.
After the burn
I said earlier that building a little fire might be fun. It was, though I smelled like smoke for hours afterward. The flames burned brightly with the aid of a fireplace lighter, then the embers hung around for a good ten more minutes or more.
Somehow this approach seemed to make the most sense to me. If the plants rely on heat, this solution would provide it. If they rely instead on some secret ingredient that emanates from burnt wood, this method would give them that. And if the burning helps break through the hard seed coat, this method could do that, too.
It goes without saying: You need to use a non-flammable pot to do this!
Boiling the seeds
And my last method was boiling the seeds. I brought water to a boil, threw in a few seeds, and picked a forty-five second time period to leave them on the heat. The boiling seemed to soften the seed coating, and I tried to pull off what I could.
No proper scientific experiment is complete without a control group, so there were some additional seeds that I tortured in no way. I was running out of seeds pretty quickly.
Drawer with pots of seeds
Each of the groups of seed were then potted up, labeled, watered, covered with a bag, and then put in the low veggie drawer next to where I store the film for my cameras. Now I keep them moist–not wet–and wait for two months. At the end of November I’ll take the pots out and move them to my unheated greenhouse or maybe a warm windowsill, for temperatures higher than in the fridge. After their various tortures and a proper period of stratifying, maybe I’ll be crowded with so many manzanitas that I can give them away to everyone I know in the spring. Or not.
I’ll post the progress as I go along…
October 01 2008 | Categories: gardening • my garden • plant profiles | Tags: Arctostaphylos pungens • fire ecology • germination • Mexican manzanita • pointleaf manzanita • scarification • seeds • stratification | 3 Comments »
I had a wish list with me on my last prilgrimage up to Las Pilitas Nursery, a specialist in California native plants located about a fifty-minute drive north of my house. One of the plants on the list was pointleaf manzanita, a.k.a. Mexican manzanita, Arctostaphylos pungens.
Pointleaf manzanita plant [ source ]
There are dozens of different manzanitas. Some creep along the ground. Others approach being tree-sized. The Las Pilitas selection of this species has the characteristic nice red manzanita bark, a graceful upright growth habit, terrific drought tolerance, plus a mature size that was perfect for the places I wanted to put it: about six feet tall and four wide.
When I got to the nursery I found one plant remaining, in a five gallon pot. Valerie at the nursery and a gentleman were looking it over, and he clearly was interested. They noticed me. There was talk of arm-wrestling.
In the end I guess I looked intimidating and the gentleman walked away. The prize was mine. So I came home with a nice large starter plant for where I wanted one for the front yard. I’d wanted several more, however, to put along the back fence. While I could have ordered some plants, I thought it might be interesting to try growing some from seed.
The most excellent Theodore Payne Foundation in the Los Angeles area offered seeds for this manzanita, along with the über-weird and wonderful Coreopsis gigantea and a handful of other plants that proved irresistable at from-seed prices.
The shipment arrived last week, almost no time after I’d sent in the order. (It’s pretty old-school–You actually have to fill out a paper form and mail it in…)
Envelope with acid-soaking instructions
When I opened up the envelope, however, I knew things weren’t going to be easy.
H2SO4? Isn’t that sulfuric acid?
September 30 2008 | Categories: gardening • plant profiles | Tags: Arctostaphylos pungens • Las Pilitas Nursery • Mexican manzanita • pointleaf manzanita • seeds • sulfuric acid | 2 Comments »
