Oak Seedlings

Live Oak trees on a golden hillside, broccoli on toast,  a very Californian landscape.  Live Oaks are a common evergreen in our area, with holly-like leaves.  The other type of oak around here, although not as common, are Valley Oaks.  They do lose their leaves and have a tendency for twisted, gnarly limbs giving them a spooky aspect in the winter.  The tree below is just across our driveway, in a neighbor's yard.  Looks like a dragon in this silhouette from the front porch.

With oaks all around, there are going to be acorns, and acorns get eaten, picked up, moved, dropped and buried by all sorts of critters.  Squirrels, birds, pigs, etc.  In particular, the Western Scrub Jay likes to bury them in the soil and then, usually forgets about them.  In areas  landscaped with wood chips, there will be dozens of seedlings popping up in the spring.  I'm not sure what it is about wood chips, maybe it's just easy for the Jays to stash them under the litter, without digging around too much.

This is a typical Live Oak seedling, one that popped up this winter, at about 4" tall.  Acorns mature and drop from the trees starting in September and continue through November, sometimes later.  So this one's probably been under the wood chips for a couple of months.   They're cute and everything, but if we leave them alone, they just get stepped on,  mowed over, sprayed with Roundup, or eaten by deer.  So it occurred to me to try'n transplant some of them to containers, grow them to a decent size, and then plant them around the property.  Not so easy it turns out.

I've found that there are (at least) two rules of thumb.  First, don't try to move an oak seedling when it's stressed by hot weather. Do it in the winter, when they're 'relatively' dormant or just emerged.  Second,  the tap root grows quickly,  up to a foot before the seedling sprouts. Don't bother with seedlings that are more than six inches tall, they're too hard to dig up with plant and roots in one piece.   The seedling here is just right for transplantation,  acorn still attached.

The soil around here is adobe clay, it's nasty. In the winter, it has the consistency of modeling clay, sticks to everything.  In the  summer it has the consistency of a brick, so digging in the winter is easier, as well as advisable for getting seedlings out alive.  A technique that works pretty well is to use two garden trowels, inserted at an angle so that they meet 6-8" below the seedling.  Where the two trowels meet, they shear off the tap root.  It's ok to cut the tap root,  as long as the rest of the root ball stays intact.  If the tap root is not sheared you may pull the dirt up, without the plant. 

I guess one advantage of clay soil is that it keeps the root ball intact.  Not all seedlings dig up this nicely, you hope they all end up looking like this.  Even if they're transplanted while dormant, oak seedlings don't seem to like going 'bare root'.  Keeping the small roots attached to the soil  is key. Once it's out of the ground I put the seedling into a 20 oz drink cup, or a pot that is at least 8" deep, to settle in for the winter.  I use potting soil,  or some sandy soil mixed with composted horse manure (plenty of that around!).  20 oz cups are nice, with some holes punched in the bottom.  They're cheap, and recyclable.  But, it's hit-and-miss, with not more than 50% of transplants making it through the following spring.  Still working on techniques to improve  the survival rate.

Those that do make it into the late spring get re-potted to two or five gallon containers, where they can reach a size suitable for replanting. The 20 oz drink cups are nice (again), because of their shape,  The whole root ball slides out easily and intact.   A 12-18 month seedling can be from 12-18" tall, and will usually have a tap-root balled up at the bottom of the container.

While in a container, they need water, lots of  it during the summer months.  Around here it's consistently 80-100 degrees, with no rain from June through September.  I'll water at least a couple of times per week.  When a transplant gets stressed, it starts to lose it leaves and often can't recover.  But healthy plants, with adequate water will grow quickly and can be planted the next winter. I haven't experimented with fertilizers,  leaving it to the mulch and potting soil to provide what's needed.  It sounds however, like some fertilization  might help.  I'll give that a try on some of the new plantings.

'Generally, young trees can be fertilized to establish them quickly. Nitrogen is the primary nutrient of value to oaks. Prior to rain or irrigation, fertilizer can be spread on the ground to cover the outer two-thirds of the root zone. An alternate application method is sometimes useful.  Fertilizer can be injected with water or placed in holes dug into the ground, 18 inches apart, along the tree’s drip line. Fertilizers should be applied at a rate of two to four pounds of actual nitrogen per thousand square feet of area. (For example, if a nitrogen fertilizer contains 20% elemental nitrogen, then 10 to 20 pounds of fertilizer would be applied per thousand square feet of area). Organic nitrogen or slow release nitrogen sources are preferable. Organic sources should be applied in late winter to allow the nitrogen to move into the root zone. Inorganic sources should be applied in late spring after the first flush of growth.'

One year old seeding replanted

I've read recently that starting oaks from the acorn has a better chance of success than transplanting seedlings.   It seems that the transplant itself is a shock that young trees can do without.   Still, the seedlings are all around, so we'll probably keep transplanting them, as well as growing them directly from seed.  It was late in the year when we wanted to try our luck with acorns so only a few were left on the Live Oak trees.   I managed to find a handful of Valley Oak acorns on the ground under the 'dragon' tree as well.   I'll post more about that experiment when we see some results!