Are you interested in apricots?

I’m propagating a couple of interesting apricots.

One is/was the co-state champion tree for Colorado, with a trunk much larger than I can get my arms around, but it’s in severe decline. I grafted a copy in about 2014 that’s now reached bearing age.  Apparently the original is well over a century old. It is also more reliable than any other apricot I’ve seen in the Boulder area, producing a few fruits during many years that other apricots are barren.  In 2008 we made quite a bit of jam from groundfalls. (Visit this tree on the north side of the West Senior Center in downtown Boulder).

The other is from 8100′ in Garfield County, next to a dirt road, two thousand feet above the Colorado River. This had fruit when I first noticed it in the summer of about 2003. It bore a good crop a couple of years ago. This tree is in quite a xeric spot — dry hillside, south facing — but has been doing pretty well there. As with the other tree, fruits are small, but good-tasting.

This apricot tree, on the Coffee Pot Road in Garfield County, is the highest fruiting apricot I've yet seen in Colorado.

This apricot tree, at 8100′ elevation on the Coffee Pot Road in Garfield County, is the highest fruiting apricot I’ve yet seen in Colorado.

I’d like to get both of these trees grafted onto rootstocks and distributed to several interested, experienced gardeners/fruit growers.  For this next round of propagation, I want to ensure the continuation of these varieties, but in future years I think it would be great to see them more widely distributed.

If you are in the (general) Boulder/Denver area, and are interested in growing one or both of these, please contact me (Eric) and let me know a  bit about you and your experience with fruit growing.  It’s conceivable I’ll have some small trees in 2021, but due to a delay in receiving some rootstocks, it could be 2022.

Short of providing actual trees, I’m also happy to provide dormant scions/budwood or Summer budwood.  Let me know if that’s of interest.

Resources for grafting apples

If you’re participating in the Guidestone Colorado AgriSummit virtual grafting workshop, here are some resources you might find useful. These are what I use for dormant grafting in my unheated garage — generally in March in Boulder, CO.

NOTE: I’ll be adding to the list of requested links & resources in BOLD TYPE, just below, the morning of Friday, 4/17:

ROOTSTOCK GUIDE
— Feel free to email with any questions.

PROPAGATION TEXTBOOK —
Plant Propagation: Principles and Practices, by Hartmann & Kester. There are many editions. Find a used one for a low price on ebay, perhaps?

GATHERING SUMMER BUDWOOD — this article is right here on the web site.

(Below is just a TOOLS & SUPPLIES list. Look elsewhere for archived instruction and safety information)

KNIVES: The knife I show in the grafting workshop is the Victorinox Floral/Grafting Knife. It is under $20, beveled only on one side, and has a straight blade. I have done hundreds of grafts with mine, so they seem to last well. GrowOrganic.com has a very similar one, also by Victorinox, that’s under $15. Cheapest option: use whatever very sharp knife you have on hand. I like using single-beveled knives, because it’s easier to make planar cuts with them, but there are plenty of people grafting successfully with utility knives.

Are you looking for a left-handed grafting knife (bevel on the other side from most grafting knives)? Try Due Buoi Agriculture — they have ’em (thanks to Reed Loefgren for the tip).

SHARPENING STONES: A very sharp knife is important, so be sure you have adequate sharpening equipment, unless you’re using disposable blades. I use diamond sharpening stones, but there are other options. NC State has a good video showing how to sharpen a new knife.

GRAFTING TAPE: I started out using 1″ Parafilm grafting tape, and still use it sometimes. A roll is only about $5 — which may be a consideration if you only need to graft a small number of trees. If you’re doing larger quantities, say for an orchard, consider Buddy Tape, which I absolutely love. Buddy Tape is more expensive, but there are many times more usable pieces per roll, so it’s probably roughly the same cost per tree as Parafilm. Cheapest option: cut strips of plastic from bread bags (you’ll need to remember to cut these off in mid-season so they don’t girdle the young tree).

HAND PRUNERS: I recommend bypass rather than anvil pruners. Be sure you get some that you can sharpen. I like Felco pruners, which can be disassembled to sharpen the blade. They’re a bit pricey, but spare parts are available, and they can last decades if maintained well. I use the Felco 8, but they have models for left-hand use as well as for smaller hands. Pruners don’t need as fine an edge as grafting knives. I use a small triangular file to sharpen mine. Cheaper option: any sharp pair of bypass pruners.

HAND PROTECTION: For cleft cuts, use an old CD or drill a hole in a board.

3-GALLON PLASTIC NURSERY POTS: I use these to hold my rootstocks in their bundles, and to hold finished grafts while they are healing. Nurseries and landscape contractors may have used ones that they’d give you. I block the drainage holes with small stones, so that water can drain but the moist sand I use to fill the pots won’t wash out.

NURSERY TAGS: If you’re just doing a few trees, these aren’t so important. You can tie pieces of string loosely around your finished grafts and tie different numbers of knots in the tail ends of the strings to designate the cultivar (make a written record of what means what). If you need more detail, embossable aluminum tags are nice because there’s no risk of ink fading in the sunlight.

ROOTSTOCKS:
Copenhaven Farms and Willamette Nurseries are good sources for larger quantities (bundles of 25 & up). Order in the Fall to ensure they have inventory. I suggest ordering smaller quantities from Fedco Trees or Cummins Nursery. Learn a whole bunch about different rootstocks before just buying some. I mostly use EMLA-111 and Antonovka for apples.

SCIONWOOD:
Masonville Orchards in Colorado has lots of cultivars.
Fedco Trees has a good selection.
And, you can cut your own scionwood in January from local trees. Read up on how to collect and store scionwood.

OTHER SUPPLIES:
Moist sand for pots that hold rootstocks and finished grafts.
Isopropyl alcohol to sterilize blades between grafts.
Small candles if you’ll be sealing scion tips with candle wax (keep the candles away from the flammable alcohol).

Selecting, cutting, and storing dormant apple scionwood

January Late January into mid-February is what I consider the best time to collect dormant apple scionwood in the Boulder area (note, after a few years of cutting scions here, I’m now of the opinion that waiting until February is suboptimal). Later, and a warm winter could mean buds already swelling — i.e. they are no longer dormant, but starting to grow. We want the wood to be dormant because when we graft it to a rootstock, the junction will need to heal before the rootstock can supply the scion with water and nutrients. If the scion starts to grow before the graft union heals, it is likely to die from lack of water for the emerging leaves.

Once the time has arrived for collecting wood, get a sharp pair of hand pruners and head out to the trees. Look for last year’s wood. Follow a relatively upright branch downward past each bud until you get to a spot where there’s a bit of a ringlike ridge around the branch. Small branches often grow out from a location just below here, and there are also usually a few buds crowded right above this spot. Higher up, the buds are farther apart.

Identify the bottom of last year's growth, where the ringlike structure and crowded buds are.  Cut scionwood from the portion of the branch above this area.

Identify the bottom of last year’s growth, where the ringlike structure and crowded buds are. Cut scionwood from the portion of the branch above this area. The diameter of the scionwood that’ll be cut from this branch is nearly ideal.

(As an aside for those who read Selecting budwood for summer bud grafting, the wood we’re looking for now is the same that one would have selected last summer for bud grafting, only now it has matured and the leaves are long gone.)

Ideally I’d cut scionwood that’s about 6-7mm (1/4″) in diameter, which is easy to work with and is close to the diameter of typical rootstock. However, sometimes there is no scionwood as thick as that. No problem. Get what you can, because you’ll probably be able to graft it.

Sometimes ideal scionwood is unavailable.  In that case, get the best scionwood you can.

Sometimes ideal scionwood is unavailable. In that case, get the best scionwood you can. Note the ballpoint pen for scale. The scionwood here is smaller than ideal.

Once you’ve cut your scions, they might look like this:

Here is the cut scionwood.

Here’s the cut scionwood. The piece on the left is nearly ideal. The thin wood on the right has just been cut from the branched wood below (the branched wood will be discarded).

Cut the wood to lengths that will fit in a gallon ziploc or similar plastic bag. Trim off the top inch or so, unless your scionwood is very short. Seal all cuts with a quick dip into a candle, to coat cut surfaces with wax. Of course, don’t leave the wood near the burning candle for more than a the fraction of a second it takes to coat the end with wax.

It’s hard to see the wax on the ends, but here is trimmed and sealed scionwood:

This scionwood has been cut to length for storage in a ziploc bag, and cut surfaces have been sealed with wax from a burning candle.

This scionwood has been cut to length for storage in a ziploc bag, and cut surfaces have been sealed with wax from a burning candle.

Lastly, mark your scions as to identity with some cloth medical tape or something similar. Store them in a refrigerator if possible, but do not put them into the fridge where you keep your food — gases given off by some foods may encourage the scions to break dormancy. I have a small ‘dorm fridge’ that I start up each year just for grafting season. If you don’t have a refrigerator, consider putting the scions on the shady side of a building (north side in our hemisphere), covering with enough leaves or other insulation to prevent freezing.

Finished scions, ready for storage until grafting begins in late March:

This scionwood has been labeled and is ready for storage.

This scionwood has been labeled and is ready for storage. These scions are from a USDA-collected wild apple I’ve grown out, and have a code number rather than a name like Honeycrisp or Fuji.

Selecting budwood for summer bud grafting

If you’re attempting T-budding, or cutting budwood for others to graft, now’s the time. I usually think of July 15 – Aug 1 as the best time. Earlier, and the buds may not be mature. Later, and the bark on the rootstock may not be slipping. Here’s a brief guide to selecting and preparing budwood.

First, find this year’s growth on a relatively upright, vigorous branch. You’re looking for the portion of the branch that has individual leaves attached directly to the branch … that’ll be the topmost section of the branch, right out to the tip. If you start at a branch tip and work your way down, make note of the spacing between the leaves. At the very tip they may be close together, but just a little ways down the branch they’ll be further apart. All of this is the current year’s growth.

The tree grows buds this summer at the junction between leaf and branch (the axil). They’re dormant for now, but each of these axillary buds has the potential to turn into a new branch next summer. The goal of T-budding is to remove these buds, get them onto the host rootstocks, and let the two parts knit together while the tree is still actively growing for the summer. If successful, next summer the bud will start growing and become the trunk of the new tree.

This is good budwood in the middle of the current year’s growth. Note that individual leaves attach directly to the apple branch. Axillary buds appropriate for grafting may be found where each leaf attaches to the branch.

As you continue down the branch, eventually you’ll reach a point where the leaves, or the scars where leaves could have been, get quite close together, and there is often a ringlike structure around the branch here. This is the bottom of the current year’s growth. Below, leaves don’t attach individually and directly to the branch, but rather to side branches of the branch you’re examining.

Note the close spacing of leaves on the branch in the top half of the image. That area is the bottom of this year’s growth. Below is older wood.

In the next several photos, you can see how I prepared budwood from an apple branch.

1. Here’s the branch as cut from the tree

Here is a branch from an apple tree in my yard. The bottom half-centimeter is last year’s wood, and everything above is this year’s growth.

2. With hand pruners or scissors, remove each leaf blade, but leave the petiole (‘leaf stem’) to use as a bud handle later.

Leaf blades have been removed. Petioles (‘leaf stems’) are left on the branch.

3. Close up of prepared branch.

The petiole attaches the leaf blade (now removed) to the branch, and makes a fine bud handle.

4. Finished budwood. The middle section provides the best budwood.

Finished budwood. Select only the middle section if your branch is long enough, as these are the best-quality buds. Upper and lower portions will be discarded.

Budwood is perishable and should be used as soon as possible. That said, it is frequently shipped through the mail successfully. Put the budwood in a plastic bag with a zip seal, and mail it in a padded envelope.

(I hope eventually to post how-tos for T-budding … but for now just wanted to get budwood selection information out to some people with heirloom apple trees that they want to propagate)

Did you learn about us in Colorado Gardener?

The June 2017 edition of Colorado Gardener has an article we contributed on the topic of popularizing grafting skills as a way to build appreciation for Colorado’s historic apples. In addition to the better-known West Slope fruit-growing districts, Canon City, Wheatridge/Arvada, Boulder, Longmont and other areas on the Front Range once had vibrant orchard industries. There are surely hundreds, possibly thousands, of trees still alive from that golden era of apple growing before the advent of supermarket chains. These trees have both historical and horticultural value.

This tree in Boulder's Whittier neigborhood was described to us as being a big tree when the previous owner of the property was young.  It's trunk, though decaying, is very large.  We have grafted several new copies of this tree. (c) 2017 by Eric Johnson

Among these elder trees are surely some lost varieties — cultivars known to have originated here but which are otherwise forgotten. Because they grow well in our conditions, they represent an opportunity for small growers whose focus is local markets, as well as backyard orchardists.

With inspiration from Montezuma Orchard Restoration Project (they’ve already rediscovered the Colorado Orange and other lost apples, and done terrific work to bring back the orchard industry in the Cortez area) and others, we’re beginning an effort to locate old historic apple trees along Colorado’s Front Range and graft new copies of them. We’d welcome your help, if you’re interested in moving this project forward — a little, a lot, or anywhere in between.

As a starting point, we need to know where old trees are and develop criteria for prioritizing which ones to save. If you know of trees we ought to consider, can you provide an address or (better) GPS coordinates, plus a couple of photos? (Please be respectful of private property and appreciative of owners who have kept these special trees alive)

We anticipate that during the busy summer months we won’t be able to visit many trees, but can probably put more energy into that in September/October. We’d love to be in touch now, though, with folks who’d like to work on Front Range apples and orchard history. Please send us a message!

Meanwhile, what else could we all work on? How about bud grafting? After a successful dormant grafting workshop in April, we’d like to tackle a workshop or two of bud grafting this summer. If you have a tree that needs preserving, there’s a window of opportunity in July when apples can be easily ‘budded’. We have a small supply of rootstocks onto which buds can be grafted. Interested in bud grafting this summer?

This is going to be a lot of fun.

Freeze damage to tree fruit buds and blossoms

The Front Range is expecting a winter storm with temperatures expected to reach the low 20’s Fahrenheit, 3 to 5 below 0 Celsius. This event will likely cause significant bud and blossom death in fruit trees in this area, as well as to other fruits and vegetables. How much damage is determine by the specific plant (apple, peach, grape, spinach, etc) and the development stage.  There are methods to limit or prevent damage, and we recommend you do some research and apply as appropriate/reasonable to your specific plants, location and resources.  Mark Longstroth with Michigan State University Extension has a couple of tables with critical temperatures for tree fruits, which you can find here: http://msue.anr.msu.edu/news/freeze_damage_depends_on_tree_fruit_stage_of_development

This weather event is not expected to out right kill any apple trees on the Front Range, but local conditions and the health of individual trees vary, so it is possible.  We will keep an eye on our trees around Boulder County and certainly take note of this event.

Grafting workshop, Saturday 3/18

Want to learn how to graft apples? We’re planning a workshop for Saturday, March 18, mid-morning to about noon. Rootstock and choice of apple varieties will be available. The cost will be a few dollars. Come and graft your own tree to take home! If interested, please let us know: http://bit.ly/contact_wm