Heirloom Blueberry Cuttings, Part III, The Box

In the previous articles in this series, we discussed the background behind our experiment in heirloom blueberry cuttings, and prepared the cuttings themselves. In this article, we expand the series by describing the box and how we used an 18-unit pressed fiber egg carton to house the cuttings. The plastic six quart box is shown below, along with the egg carton nestled inside it:

We like using these pressed fiber egg cartons because they disintegrate so easily when wet. They are practically all wood fiber, with little or no obvious binder or coatings. As with commercial pressed fiber or peat-moss planters, the egg carton gives a great environment to hold water and nutrients while roots are small, and yet allows easy penetration when the roots are larger. Not all paper is suitable for this purpose, however, as many office papers will contain binders, clays, anti-fungal agents and so on which are detrimental to plant growth.

The first step in the process is to remove the cover from the carton, and put it in the plastic box, upside down. This was already done in the previous article to help in the soaking process for the cuttings. We used the cover to help absorb water and keep a humid environment for the cuttings.

Next, we prepare the egg side of the carton by using a shop knife to score the bottoms and sides of each egg cup, as shown below:

The idea here is to give the tiny root hairs somewhere to go and something to grab, rather than keeping them balled up inside the cup until they are much larger and deformed. Not shown in this photo, but important when it is time to repot the cuttings, is to score the interstitial web between the egg cups.We are pretty aggressive about this, cutting down to that molded horizontal line, or farther.

Next, on the other side, we cut three sides of the tower tips and leave the fourth as a hinge, as shown in the closeup below:

The idea here is to put the larger stems through these holes to help them remain vertical in the cups. It isn’t perfect, they’ll still slop to the side a bit, but it is much better than counting on potting soil alone.

Now, it is time for the cuttings themselves. We used the tower tips to hold the longer cuttings, and just dropped the small cuttings into the cups. Try to be careful to put the cuttings in right side up. We’ve done this several times, and still managed to get a couple of them upside down! The raw distribution is shown below:

Next, we spooned in potting soil around the cuttings, straightened each cutting as much as practical, and packed in the soil around them, slightly above the level of the egg cups:

Finally, we then soaked the cuttings and cardboard, again with reverse osmosis water rather than chlorinated tap water, up to the level of the wells remaining after the tower hinges had been cut. This first watering, we are trying to wet the cardboard and the soil, rather than feed the plants. From the perspective of the cuttings, they are still soaking.

For potting soil, we specifically avoided variations called “potting mix” as our experience with these is that they are mostly sand with a lot of fertilizer. We were concerned that the fertilizer would burn the cuttings, so we wanted to control the fertilizer content ourselves. Although the Hyponex still has some fertilizer in it, the amount is small. It also has some random 1″ wood splinters, but these are easy to remove. Had we more time in this area, we would have used our own native compost for this purpose, and would highly recommend that if it is available.

Our philosophy is to avoid over-fertilizing the plants as there are no holes poked in the bottom of the bin. We are intentionally not allowing excess water to drain, and in fact want to keep the soil very wet to allow capillarity to do its job at the cut edges of each plant. As a result, over-fertilizing would result in an accumulating concentration of nutrients, which at some point would dehydrate the cuttings through osmotic pressure. We also don’t want to trigger the plants to grow in excess at this point as they would outrun their ability to feed themselves without roots.

This last point leads to our first failures with this experimental method. As you’ll see in a future post, the most robust plants are the thick cuttings, regardless of length. Most of the very thin cuttings sprouted hard, withered and died. Our experience has been that the early sprouting cuttings don’t do well, while the ones that take their time creating sprouts tend to be the hardiest. It could be that the thin cuttings just don’t have enough exposed channels to support that much activity (although in one case I think we left an air pocket around the cutting base).

In the next post, we’ll talk about fertilizers in more detail, and show some of the progress photos. In future posts, we’ll try a different approach with some thin cuttings and see how that experiment goes.


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