Answer: According to the literature, the deck is stacked against you at this point. Local seed (no more than 200 miles to the south) is best in terms of lending hardiness, and black walnut is not as hardy (to Zone 4) as its cousin the butternut (zone 3). The benefits may be that disease and insect pests aren't as likely to be around if walnuts haven't been grown in the area before. I always advise gardeners to at least experiment, because that's half the fun, anyway! If you're serious about nut or lumber production, you're better off planting tried and true cultivars available from nurseries. To maximize your success, plant in fertile, moist yet well-drained, neutral (rather than acidic) soil, in full sun. I'd choose the nuts you buried as the more likey to sprout. Start your experimental nursery of walnuts in a bed of sand and peat, or other soil medium that drains well and retains moisture. Cover seeds with several inches of medium and keep the be moist. This should result in a strong, fibrous root system that will take transplanting with less shock. It's a good idea to cover the bed with chicken wire to keep critters from exhuming the nuts. As for breaking through the hardpan, anything you do to improve the trees' chances of success is helpful. If you want to find out if anyone else has tried and succeeded/failed at walnut culture in your area, contact your county or regional forester. Hope this helps!
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