Tom's Blog

Friday, October 25, 2013

Oak savanna planting guide

Now is a good time to think about planting herbaceous species as part of an oak savanna restoration. Although planting can be done either spring or fall, the latter is the best because planted seeds have the whole winter to settle and become stratified.

My assumption is that the site to be planted has been extensively cleared of all invasive trees and shrubs. The only remaining trees should be open-grown oaks or hickories, plus scattered young oaks that might serve as "nurse" trees.

My oak savanna restoration web site has lots of detail about planting, as well as a lengthy seed planting list (PDF) with a selection of suitable herbaceous plants.

The ideal lead-in to fall planting is a good burn. This clears out most of the oak leaves and prepares the seed bed. Since the site has presumably not been burned before there should be plenty of oak leaves on the ground, so even in the absence of substantial understory vegetation there should be plenty of fuel to carry a fire. Wait for a reasonably warm day in late October or early November when it is sunny and the humidity is below 40-50% (conditions called "Indian summer"). A good wind also helps carry the fire.

If the site cannot be burned, the seed bed can still be prepared. Rent or buy a hefty leaf blower and create zones of bare soil. Depending on the size of the site, this may be a fairly time-consuming job. However, it isn't necessary to clear all the leaves off the site. Choose areas to clear that have fairly open canopy, since these will be the areas where the understory will grow the best.

My oak savanna planting guide   classifies each plant species by its light preference: no canopy (0-10% canopy), open savanna (10-30% canopy), closed savanna (30-70% canopy), woods (>70% canopy). For planting a typical savanna, the seed mixes can be simplified to prairie (0-20%) and open savanna (30-50%). Note that some of the species will grow in more than one area, so can be placed in more than one seed mix. In most cases making seed mixes will depend upon availability of each species. Remember that this is just a guide, and should be modified for each situation.

The two-bucket method is the most efficient way of planting. One bucket has the prairie mix and the other the savanna mix. The south side of a large open-grown oak should get the prairie mix whereas the north side should get the savanna mix.
The same savanna area in 2013 (11 years later). It has been burned annually, either fall or spring.
In addition to annual burns, heavy brush control should be anticipated. The clearing of the savanna brings in a lot of light, and brambles and other brush that had been suppressed can now thrive. Even annual burns will not be enough to provide brush control.

Brush control should be started about the third year after planting. This is an ideal winter cut-and-treat job, using a good brush cutter, Each cut stem should be treated with 20% Garlon 4 in oil (best), 15-20% Garlon 3 aqueous, or 50% Roundup. (See the various brush control manuals for alternative methods.)


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