How To Care for Tree Seedlings?

Several of my sour jujube seeds came up and they are about 1" tall now, in a pot outside. They have not grown much recently. How best to take care of them? I just moved them from 1/2 sun to 1/4 sun since I think the plastic pot is too hot in summer morning sun.

I do not wan to plant them in the field now since they can’t compete with weeds and rabbits may just eat them.

I’m growing my sprouts in 1 gal rootbuilder II containers for the first season. I like the root systems these containers force. The rootbuilder II containers are black plastic but they have protrusions that shade the protrusions below. I keep them in full sun all summer, but I keep them well watered. These containers along with the mix are so well drained, it is hard to over water. I actually keep a tub of water and immerse the entire container so they are watered from the sides and bottom. I have had no issues with them getting too hot but I’m in zone 7A and we don’t have too many days a year that exceed the high 90s (F).

I worry about root circling and j-hooking with smooth sided plastic containers. I have been grafting mine and those that succeed, I keep for a second growing season but upside the container to a 3 gal rootbuilder II.

I haven’t had any die so far growing them with this method. Most of mine will head to the field this year when they go dormant for planting.



Do you place one sprout per pot? My seedlings are so small now and I do not know if it is good time to repot them.

My sprouts were started from root cuttings. I put multiple root cuttings in a large flat. I waited until mine were 3" to 4" tall before transplanting. The roots are delicate when this young. My first year, I killed some that I tried to transplant when they were smaller. When I transplanted them, I took all the mix I could surrounding them as undisturbed as possible and placed it into the partially filled new container and then filled in around it with mix. I end up with one sprout in each 1 gal container. By the time they go dormant in the first year, they have filled the 1 gal RB2 and are ready to be transplanted.

Things may be different for you. I don’t know about Jujube, but other trees I start from seed focus energy on producing a tap root first and if it is not air pruned, it takes quite a while to get much root branching. So, when I I start most trees from seeds or nuts, I germinate them in flats but as soon as I see any sign of germination, I plant them in the Rootmaker 18 express trays which do the tap root pruning. They stay in those small containers for 12-16 weeks before I transplant to 1 gal RB2s.

The Jujube I’ve started from root cuttings don’t produce a tap root. instead, they start producing many small roots branching out from the cutting. My point is that 3" to 4" of top growth works well to determine when to transplant these but I’m not sure if it applies to seed grown Jujube.

I hope it gives you a data point as a starting place to experiment.



Here are the seedlings. They are still healthy, but have not grown much lately. I wish the medium level were deeper. I may just take out the rootball out and put in more media in the pot. This won’t disturb the roots. Sry the photo is upside down. The original one is good…

How deep is that medium?

About 3" to 4" deep.

Given that, If it were me, I’d probably transplant each of them into a rootmaker express tray 18 cell now while they are small and get the tap root pruned. I’d then move them to the 1 gal Rootbuilder II containers in 12 to 16 weeks. You will notice that the cells get harder to water as the roots branch and begin to fill the pockets in the mix.

To remove a seedling from one of these cells, I dunk the cell in water so it is drenched. I squeeze the sides of the cell to loosen things. I then put my hand over the cell with the seedling sticking between my fingers, invert it and give it a shake. The quickly branching root system will hold the mix together with the root ball if you timed the transplant right. If you find hunks of mix easily falling off the root ball, you are on the early side and you can wait to transplant the rest.

Best of luck whatever approach you take! They look very healthy and quite a bit like my tigertooth at this stage.

Why do you want the tap root pruned?

I also started a couple of shrubs from seeds over the winter. They are in 4" square pots and stay indoors. Again I’ve not seen much growth after the spring. They always stay indoors and the jujube seedlings always stay outdoors.

I used the 38 deep cell tray to start most of the tree and shrub seeds. It is a pain to take them out without losing the soil holding the roots. Now I only use them to start vege seeds and grape vine cuttings.

When I try to grow trees in smooth pots, I end up with root circling and J-hooking. In nature, a tree puts a lot of energy into producing a long tap root to endure it can access water in a drought. I sacrifices a lot of early growth for this insurance because it is the many tiny root tips that access nutrients.

So, root pruning containers solve the root circling and J-hooking issue. While a tree may look fine when it is young and do well, as it gets older and the roots grow in diameter, the roots constrict each other. One solution is to plant a tree bare root and physically cut any circling or j-hooking roots before planting it. The down side is that manual pruning of roots does allow a cut for disease to enter, but more importantly, we’ve just removed a significant amount of root mass the tree spent energy to develop so it take a lot of time for the root system to reestablish with a bare root tree.

Here is where root pruning containers shine. When that tap root is pruned early, it forces the seedling to do a lot of up stream root branching producing lots of secondary and tertiary roots. You end up with a very dense efficient root system. A root pruning container can support a much larger tree for a given container size. The idea is to upsize containers when one becomes full so the tree does not become root bound.

When you plant a tree from a root pruning container, you snip a couple cable ties and the container unwraps from the root ball. So, you end up planting a tree with a completely undisturbed root system that is very dense and efficient root system. Transplant shock is minimized and the tree starts growing almost immediately.

There is no free ride. What these container do is let you make a trade-off. The tree can use both water and nutrients very efficiently, but it must be able to reach them. It takes a year or so for the root system to grow far enough into the native soils to have access to deeper water. So, unless you are in an zone like I am with ample spring and fall rain, you need to commit to providing supplemental water during a drought. In my area, unless we have a drought during the first summer after planting, I can plant trees in the field without supplemental watering and they do fine. For folks planting trees in the back yard where supplemental watering is easy, there is not much down side.

Most of this research came from Dr. Whitcomb. He came up with the rootmaker products based on this research. That is what I started with and I have not ventured to using other brands, but there are now lots of brands of root pruning containers. I know a number of guys using other brands with varying degrees of success. I don’t want to sound like an advertisement for Rootmaker. I am an advocate of root pruning containers in general and I’m most familiar with that brand since that is what I use. When folks ask me about other brands, I generally point them at Dr. Whitcomb’s papers and tell them to understand the underlying concepts and make sure whatever root pruning containers they buy supports those concepts.

Here is a link that talks about the 4" rule regarding when to transplant to a large container: enter link description here

Great info!

If you want those seedling tap roots for wind protection and/or drought tolerance then you should get it into the ground.

The down side is I never like seedling trees in general until they get over about 1 foot tall. A lot of them seem to abort around 8-9" height.

I would think jujubes would have thorns when quite small to help against predation.

Actually many folks think the tap root helps with wind protection but that really is not the case. Even though shallow, a broad dense root system provides just as much of an anchor as a tap root.

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If you watch Dr. Yao’s jujube grafting video, she has the sour jujube seedlings in the field. I figure it takes at least 2-3 years to grow to pencil side and ready for grafting.

At this point, I only care about having these seedlings grow to the size for grafting. They will likely be moved. So tap roots probably won’t be kept in the original location…

I think sour jujube may be more aggressive than tigertooth as root stock. When I take dormant root cuttings from my TIgertooth in the winter, it is usually late May or June before I see top growth. If I then transplant them to the 1 gal RB2s for the summer that are too small to graft the next spring. I tried it with one that was not quite large enough and it failed and the root stock failed to regrow. However, if I transplant them into the 3 gal RB2s and keep them for a second growing season, they are easily pencil sized caliper by the end of the second year.

Dr. Yao’s video is outstanding. I re-watch it right before every Jujube grafting attempt I make.