The longleaf literature on cone collection and seed processing can appear intimidating and even discouraging for regular folks hoping to grow longleaf without aid of commercial orchards or laboratories. (See the Practical Guidelines for Producing Longleaf Pine Seedlings in Containers.) It is definitely possible, however, for ordinary people to gather cones and harvest viable locally sourced longleaf seeds. At least for cones gathered on Indian Grave Mountain in central Georgia, the techniques described below routinely produce seed batches with germination rates exceeding 80%, even for cohorts left in the basement freezer for a year or more.
Seeds and Cones
Collecting Cones
The easiest way to collect cones is to pick them up off the ground. Despite rather dire predictions in the literature about the rapid decline in viability resulting from even a few hours on the ground, I have found that cones picked up after October 1 that are still green and firm will likely contain viable seeds, regardless of how long they may have been on the ground. Thus, a walk in the woods beneath cone bearing trees is often all it takes to gather dozens of viable cones, especially if one can enlist a nimble and adequately compensated teenager or two for the effort.
While it is true that most trees will not produce large cone crops until reaching about 30 years of age, younger trees will produce some cones in good crop years, especially if grown in the open (like along roadsides). These cones can often be reached from the ground either by hand or with a pole. The longleaf literature cautions that younger trees may have a lower rate of fertile seeds but, at least in my imprecise observations, I have not discerned a meaningful difference. This may be because I still consider it a success even if I only get 10 or 20 viable seeds from a given cone, whereas a commercial operation may deem that a failure.
Further, especially at higher elevations or under poor site conditions, older trees may stay quite small. Those involved in tree improvement breeding programs may caution against using seeds from smaller trees because they could have inferior genetics. However, since longleaf are wind pollinated and self-incompatable, no more than half of a seed’s genetic material is likely to come from the female parent holding the cone. In addition, it seems possible that a tree surviving to cone producing age on an especially poor site might have some worthy genetic qualities. These older, smaller trees can definitely produce a lot of cones. I harvested 75 cones from the tree at the left in about an hour’s time while while standing on the ground with a 21’ telescoping pruning saw. Since I could probably only reach to about 25 feet, I estimate that I left more cones in the tree than I was able to collect. This tree is located at nearly 1100’ above sea level in the cracks of a rock outcrop. Despite being only about 8” in diameter and maybe not 40’ tall, this tree’s genes might be worth passing along.
In any event, I suggest keeping an eye on roadsides and other edges for trees with cones not so far from the ground.
In previous years, Environmental Defense Fund (EDF) led efforts to hand-pick cones from a bucket truck, but that approach was slow and labor-intensive. It didn’t yield enough seeds. This time, they tried a new method – tree-shaker collection. They hired Pine Star Farms from Vass to bring a special machine designed for harvesting nuts on orchards in California. Its padded claws reach forward, grab a tree and shake it. Laura Fogo, a biologist with the US Fish and Wildlife Service (USFWS), said the ground trembled under her feet and suddenly it started raining pine cones. (Read the article Piedmont Longleaf Pines)
Some landowners report bark damage from tree shakers, and the October harvest time also coincides with when most shakers are fully engaged in nut orchards, so I have not tried that technique. Out west, Ponderosa pinecones are routinely collected by contract tree climbers. (See National Fire Plan Cone Collection for Post-Fire Reforestation and Restoration Montana 2002.) Harvesting cones with tree climbers does not seem to have been used very often for longleaf, but Marty Cippolini reports success with the method on Berry College’s campus. In 2021, I hired Bill McDade, a climber from the Atlanta area, who collected a remarkable 168 cones from the tree shown at the top right. In 2022, Mr. McDade collected 124 from the bottom right tree. The cost of a qualified tree climber might end up being slightly less than renting a cherry picker along with somebody competent enough to operate it safely. Climbers can also get to trees in loations a cherry picker could never reach, and they are an interesting sight, to boot.
Extracting Seeds
Commercial orchard operations use kilns to dry cones in mass and the literature suggest that the timing of seed extraction can impact germination rate, just like the precise degree of ripeness when cones are collected or the age of the parent tree. On the scale of a citizen scientist’s activities, however, I have found that letting them dry out and open on their own in our air-conditioned basement works just fine. A cone collected in early October will open up in about three or four weeks, at which point a reasonably vigorous shaking will dislodge most of the seeds. In the meanwhile, one gets to enjoy the smell of longleaf cones, an earthy pine scent that is both unique and rather pleasant, if not quite right for polite company.
Culling
Perhaps the most important step in the collection process is separating out the viable seeds. The bad seeds are almost always just hollow shells, so the simplest method is to squeeze a seed between thumb and forefinger to see if it pops. One can get the hang of knowing how hard to squeeze after just a few tries. This method is certainly adequate on the scale of a few hundred seeds, but it is both imprecise and a bit hard on the finger tips, making it less desirable for culling larger seed lots.
Since the good seeds are not hollow, they are heavier than the bad seeds. Dr. Cippolini at Berry College adapted a machine that uses a combination of a blower and gravity to separate seeds as seen in this video.
I have developed a sounding method that also takes advantage of the heavier weight of viable seeds. Holding a large Tupperware lid or even a frisbee in my lap so that the middle is suspended, I drop the seeds and listen to the sound they make. A viable seed will make a clear, almost ringing sound that is strikingly different from the faint, pecking sound a bad one makes, a distinction that becomes readily apparent after just a few tries. While not as efficient as a mechanical separator, I have found this sounding method to be much quicker and more accurate than the squeeze method, and less hard on the fingers.
Once the good seeds are separated, future handling is made easier by de-winging. I have heard of people using tumblers but I have found scissors work just fine (especially if you can talk somebody else into helping).
Storage and Preparation
The literature is at least doubtful on whether stratification (that is, exposure to an extended period of cold temperature) promotes longleaf germination. I keep sorted and cleaned seeds in the vegetable crisper of the spare refrigerator in our basement, which probably stays somewhere between 34 and 38 degrees Fahrenheit. The germination rate does seem to improve after a month or so in the fridge, but this might just be the final maturation of the seeds and not the impact of stratification. If I do not expect to use the seeds in the next few months, I move them to the freezer where they are fine for at least a year or more.
A variety of fungi and other pathogens vex longleaf seeds, especially those that have been stored for significant lengths of time. I find that it helps to give the seeds an anti-microbial bath the morning before planting. I have used a dilute solution of household chlorine bleach for the bath. More specifically, I have used the Clorox “Splash-less Bleach” (4.25% available chlorine) I found in our laundry room, although I suspect any chlorine bleach will do just fine. My practice has been to mix 9 parts water to 1 part of the bleach from the bottle and to let the seeds soak in the bath for about an hour. I then rinse them and head for the woods. It is possible that exposure to bleach results in a chemical scarification that enhances germination rates, although that is just speculation on my part. What is for certain is that the bleach bath cuts down on the number of seedlings that succumb to fungal pathogens in the first couple of weeks following germination.
I make it a habit to pull 10 seeds out of each batch I take to the woods, which I plant in a container to provide an informal germination test (and then usually transplant to the woods using the BRB techniques described in the “Journey” section of this website). After well over a dozen such trials, I can confidently report that the methods described above will produce germination rates in the test cohort above 80%, and germination rates in the woods above 70%.
I have been able to secure several thousand viable seeds using the cone-scavenging techniques described above. For those wishing to collect at a larger scale, tree shakers, cherry pickers or tree climbers may be necessary. As Ruth Ann Grissom described one such effort on land managed by the forest service in North Carolina:
