The Drymifolia Collective

For those who want to know a little more about the project, here is an FAQ of sorts:

Who is eligible to join the project?

Initially, the project is only open to people who live in the lowlands around the Salish Sea, or along the oceanside coast of the Olympic Peninsula, and are in USDA growing zone 8b or higher. If your location usually falls below about 15°F (-9°C) on more than a few nights per decade, then it is probably too cold to have any hope of successfully growing even the hardiest avocado trees. Conversely, if your location very rarely falls below 20°F (-7°C), then you have an excellent microclimate for this project. People who are near (but not quite within) the region defined above are free to join, but may not get trees in the first distribution or two.

If you are unsure of your USDA growing zone, you can search or manually zoom to your location on this map.

Why this project, if it's such a long shot?

As our climate rapidly changes, our global and bioregional systems of food production will likely need to adapt and change as well. Avocados are a nutrient-dense fruit, but one that has become essentially a single-cultivar crop. The "Hass" avocado is unlikely to thrive anywhere in Cascadia anytime soon, but there are countless obscure historical cultivars and landrace varieties with a much wider range of acceptable growing conditions.

This incredible genetic diversity of the avocado, especially of the Mexican avocado, may mean that areas that are marginal for avocados can produce this highly nutritious fruit locally. Even if our project fails to find any varieties that are well-adapted to the Cascadian lowlands, we will surely at least find trees that can survive here, and any such trees would likely thrive in other less marginal areas where "Hass" nevertheless cannot easily be grown.

But if we do find trees that thrive in our bioregion, then they should be spread to every suitable community garden, residential yard, and orchard.

Is it really such a long shot?

Probably, yes. Our initial breeding pool includes dozens of different specimens of the Mexican subspecies of avocado (the hardiest type), but most of these particular cultivars have not been "stress tested" like our winters will test them, and their seedlings will have additional variation in hardiness. It is only after many years of data collection on seedling survival that we will be able to focus our breeding efforts and improve future seedlings' chance of survival.

In the first "outdoor" winter of our project (2021-2022), only eight out of about thirty first-year seedlings survived, and all of those were seriously damaged by a six-day freeze with a low of 16°F (-8.9°C). Most of the survivors re-grew vigorously from their roots the next growing season, reaching at least the size they were prior to the damage. Had they been larger or older, they may have survived above ground as well. In any case, it seems likely that most avocado seedlings (even from "hardy" cultivars) will not survive temperatures much below that level. Unfortunately, that is a minimum temperature that most of our region has historically experienced at least a few times per decade, even in recent decades.

Our hope is that if we distribute thousands of trees over the life of this project, we will find at least a few new cultivars able to survive our coldest temperatures relatively unscathed. As of yet, we have not found any such specimens.

How many trees are we talking about?

Presently (fall of 2023), the project collection includes grafted clones of about twenty different Mexican avocado cultivars in our breeding greenhouse. Only a few of those are expected to produce fruit in 2024, with all of them reaching fruiting size within the next few years, though we will start to cull less hardy varieties when we inevitably begin to run low on greenhouse space.

In addition to the grafted varieties, we have about 50 seedlings of various allegedly hardy cultivars that will available for distribution in 2024, and about 150 seeds that just started germinating for 2025 distribution.

Some of the trees that are distributed will be grafted, but most of them will be ungrafted seedlings. If initial tests of grafted trees show promise, a larger percentage of trees will be grafted in later years.

The plan is for this project to continue for at least a decade, and perhaps in perpetuity if it continues to produce new fruitful cultivars. If so, we would end up distributing many hundreds or even thousands of trees.

What kind of planting sites are ideal?

We are happy to help to select a planting site when you pick up your tree, or when it is delivered. Ideally, the trees should all be planted in the ground, though in some cases it may work OK to keep them in a very large container for a few years, but avocados are difficult to keep in pots long-term without impeding their growth. Container trees also usually suffer damage from frost at higher temperatures than in-ground trees, so they will require more protective measures.

Avocado trees seem to like the local glacial deposit soils, though they will do best with an added source of nitrogen, such as mulching with compost or the occasional application of organic fertilizers like fish emulsion. The trees shouldn't be planted in any location where water regularly collects, though planting atop a mound of soil may help in such situations.

Sunlight and microclimate effects are also something to consider. Young avocados may appreciate some shade on hot summer days, but the mature trees will want to be in full sun. Therefore, any planting location should not be shaded by other mature trees for a significant portion of the day. Planting a tree next to a south-facing concrete or stone wall with good sun exposure will generally give the tree a much better chance of surviving cold weather, so that's always a great option if you have any such spots available.

What is expected of members?

There is no charge for membership, and the only ongoing requirement is to post updates about your trees on this website at least a few times per year. Those updates will be as simple as submitting an online form, and will include information like an estimate of the size of the tree, photographs, and notes on any pest pressure or frost damage. Any sign of flowering should be reported immediately so we can bring pollen from other trees to improve the chance of fruit setting.

We do also ask that you care for the trees as best you can. If feasible, avocados should be watered during our summer months for the first few years, and even in later years they will grow more vigorously when watered regularly during dry weather. However, not all locations can be easily watered, and it may be unnecessary in many situations as well, depending on soil moisture levels in your microclimate. If you wish to protect the trees while they are young, that is fine, but please let us know the type of protection you have given them in your updates, so that we do not misjudge their hardiness.

While there is no need to volunteer in any other way, there will be opportunities to help with grafting, tree deliveries, cutting collection, and other similar tasks, both for those who have the skills necessary and those who wish to learn them with hands-on practice.

The only other requirement is to allow cuttings to be taken from any of your trees that survive. Those cuttings will be propagated both in our breeding greenhouse and for distribution to other members. Similarly, if you decide you no longer want to participate in the project, or if you will lose access to the location where a tree is planted, please notify us so that we can collect cuttings to keep the tree's genetics in our project.

What do members get from joining?

Free avocado trees! We will also help you with site selection and planting, and members will be the first to receive clones of any other members' trees that show promise in our region. Members whose trees have died over the winter (or summer!) will be given higher priority when trees are next distributed.

And of course, if we succeed, you may get a slightly more resilient bioregional food system in the face of our rapidly changing climate.

Ready to join?

If this sounds like a project you want to be a part of, then here's the sign-up form. And if you have any other questions not addressed on this page, email us and we'll do our best to answer them. Either way, thank you for stopping by!