Hazelnut

Plant at least two unrelated hazelnuts, or you get no nuts

Set bare-root dormant plants in spring on a site with good air drainage, not a frost pocket, and plant at least two genetically different hazelnuts rather than two divisions of the same clone. Space them 15 to 20 feet apart in an orchard planting, closer if you are growing them as a hedgerow shrub. Hazelnuts are self-incompatible: pollen from a plant cannot fertilize the female flowers on that same plant, so a lone shrub or a block of one clone flowers heavily and sets nothing. Pollen also travels on wind, not bees, so partners need to be close and their bloom has to overlap.

Deep-water new plants through their first two summers

Give newly installed hazelnuts supplemental irrigation for at least their first two years. Water deeply and periodically, then let the soil in and around the root zone dry moderately before watering again. Do not plant them in turf and water them on the lawn's schedule. A young hazelnut's roots have not yet reached beyond the planting hole, and the deep-then-dry rhythm pulls roots downward instead of holding them in a constantly wet surface layer where this species, which demands good drainage, is prone to root rot.

Feed only in spring, and only if the plant asks for it

If the shrub is growing weakly or yielding poorly, apply fertilizer in spring as growth begins. If it looks healthy and is carrying a decent crop, skip it - no fertilizer is needed. Let a soil test rather than a calendar decide the rate. Hazelnut is fertilized in spring because that is when it is actively taking nutrients up and can use them; feeding later in the season pushes soft growth instead of nuts.

Renewal-prune about a sixth of the oldest stems while dormant

While the plant is dormant and leafless, cut 15 to 20 percent of the oldest stems out at ground level, taking the thickest and least productive wood first. If you are keeping a tree form rather than a thicket, also cut the root suckers off around the base; if you want a hedgerow, leave them. American hazelnut is a multi-stemmed shrub that spreads by rhizomes and bears its best nuts on younger wood, so replacing a fraction of the old stems each year keeps the plant in productive wood without ever losing a crop to a hard renovation.

Eastern filbert blight: look for cankers on bare wood

With the leaves off, walk the stems and look for sunken dead cankers carrying rows of black football-shaped bumps, often in pairs. Cut any affected branch off two to three feet below the canker, and disinfect your pruners between cuts for at least 30 seconds in 70 percent alcohol or a 10 percent bleach solution. Burn, deep-bury, or chip and fully dry the prunings. American hazelnut is the fungus's native host and tolerates it - cankers spread slowly or never appear, and the shrub can live almost indefinitely with it. The catch is that your healthy-looking plant is a spore source, and any European hazelnut nearby has no such tolerance and will be killed by it.

⚠ Do not put a preventive fungicide program on American hazelnut. The bud-break chlorothalonil schedule is for susceptible European hazelnut; this species does not need it and chlorothalonil requires 120 days between the last application and nut harvest.

Filbertworm: check kernels before you commit to a harvest

As nuts fill and approach ripeness, crack a sample and look for a larva ranging from beige to pink with a dark brown to black head, up to about half an inch long, or for entry holes and frass at the shell. Rake up and destroy fallen and unharvested nuts rather than leaving them on the ground under the plant, which is the cultural control the source gives for keeping numbers from building up. Filbertworm larvae overwinter in organic matter or soil beneath the planting and pupate in a silk cocoon the following spring; the moths emerge late spring to early summer, lay eggs singly that hatch in 8 to 11 days, and the larvae bore into the fruit to feed. Last year's dropped and unharvested nuts are what carry the population into this year, so sanitation under the plant is the lever a home grower actually has.

Handpick once the husks brown, and keep going back

Nuts ripen from late September through October depending on your site. Handpick clusters after the surrounding husks have browned, and collect the dropped nuts from the ground several times a week rather than waiting for one tidy harvest day. Ripe nuts usually drop to the ground upon ripening rather than holding on the plant, so a single harvest day loses the crop to the ground and to squirrels, which prize native hazelnuts heavily. Repeated handpicking of browned-husk clusters plus frequent ground collection is what puts the crop in your basket.

Dry the nuts within days of picking

Dry hazelnuts soon after harvest at 95 to 105 degrees F for 72 to 96 hours. Spread them in a single shallow layer with air moving through, and do not exceed that temperature range. Freshly picked nuts carry enough moisture in the kernel to mold or go rancid in storage, and this is the window where a good crop is either kept or lost. Too much heat instead of too much time will cook the oils and ruin the flavor.