GROWING CHESTNUT TREES

A chestnut is the edible nut of the chestnut fruit, produced by thechestnut tree (Castanea sativa, Castanea dentata, Castanea mollissima).Chestnuts are native to the Mediterranean areas of Europe, China, andNorth American continent. Unlike most nuts, chestnuts contain primarily sugars and starches instead of oils and fats, leading to regional nicknames like "bread tree". Another thing that makes chestnut trees different is their ability bear reliably and annually, as opposed to most other nut tree species that only produce good crops every 2-3 years. Chestnut trees are cultivated all over theworld, however in North America, all American and European varieties are difficult to establish east of the Rocky Mountains due to chestnut blight. Due to this it isimportant to choose a species that is right for your area.

Choosing a Variety

Size

Chestnut trees vary in size from the very large American species that grow over 80' tall, to the mid-range European cultivars that reach around 65' in height, and the smaller Chinese species that top out around 40' at maturity.

Type

Chestnut trees are usually divided into three different types: American, European, and Chinese. American chestnut trees tend to be the tallest with the sweetest nut meat, but tend to be vulnerable to chestnut blight and should be grown only in area that do not have chestnut blight (typically west of the Rocky Mountains). European chestnuts are mid-sized trees with larger nuts and more disease resistance than American chestnuts. Chinese chestnuts are much smaller trees than either the European or American species, but produce large nuts and considerably more pollen making them valuable as pollenizer trees.

Pollination

Unlike fruit trees and berry bushes, nut trees are mostly wind pollinated instead of insect pollinated. In general all species of chestnut trees can pollinate each other, with the exception of pollen sterile cultivars that are bred for larger nuts at the expense of pollen production. Chestnut trees do not require any bees or other insect pollinators to produce nuts, but need to be planted in such a way that local wind patterns will reliably blow the pollen where it is needed. Pollen from chestnut trees will, in dry conditions, travel up to 200' away.

Ripening Time

Chestnuts don’t ripen at the same time and chestnut harvest time can span as much as five weeks, although the nuts generally ripen in a 10 to 30 day span of time in mid-to-late summer. Allow the nuts to fall from the tree naturally. Avoid trying to pick the nuts; aside from the spines, the unripe nuts will not release easily, which may damage the branches. Additionally don’t shake the tree, which may cause immature nuts to drop, and prevent them from ripening fully. The best way to harvest chestnuts is to gather the nuts after they fall from the tree.

After the chestnuts fall from the tree, watch for the spiny burs to split. Don’t harvest chestnuts if the burs are still green and closed because the nuts inside will be unripe. Harvest the nuts every couple of days. Waiting too long can allow the nuts to over ripen and quickly lose quality and flavor. When the burs have split, roll the nuts gently but firmly under your shoes, using just enough pressure to release the chestnuts. Avoid jumping or stomping, which will crush the chestnuts.

USDA Plant Hardiness Zone

Chestnut trees are hardy to USDA zones 4-9, unless otherwise noted. This rating tells you the minimum winter temperature the plants typically survive when properly hardened off. Make sure you consult the USDA Hardiness Maps website, which provides information on the average minimum winter temperature in your location, by zip code. Your USDA Plant Hardiness Zone does not reflect the many of the other factors in successfully growing apple trees, including length of growing season, rainfall amounts, soil quality, and chill hours. Consult your local extension service for more detailed information about your local growing region and the factors you will need to know when selecting fruit trees for your home orchard.

Chill Hours

All plants have what are called a "chilling hour requirement" in order to flower and produce fruit. Chilling hours are defined as the cumulative period of time between 45 and 32 degrees Fahrenheit and vary from region to region. The majority of apple trees have a chilling hour requirement of anywhere from 500-1000 hours, with some requiring more and a few requiring as little as 200-300 chill hours to blossom and produce. Apples trees that require less than 600 chilling hours are considered "low chill" and are generally more resistant to more intense summer conditions than apples trees with higher chilling hour requirements. The general chilling hours available for you specific location can be found online or determined by your local extension office.

Where to Plant your Plant

Chestnut need to be planted where they receive at least 8 hours of direct sunlight measured in early summer (late June to early August). Sufficient sun exposure triggers the initiation of new flower buds for the next growing season, without which there will be no nuts. Nut ripening and flavor development are also benefited by the carbohydrate production stimulated by the sun, as well as it’s heat.

Chestnut trees tolerate a wide variety of soils so long as they are well drained and moderately rich with a pH around 6.3-6.8. Improve your soil where you intend to plant by mixing an inch or two of plant based organic matter(manures are best for vegetable gardens), peat, or coconut coir into an area 1 1/2 to 2 times the diameter of the needed planting hole and up to a foot deep. A 2-4” deep layer of mulch (straw, leaves, or wood chips)applied after planting will continue to improve the soil.

Allow sufficient space for both the top of the tree and it’s roots when selecting the planting location. Refer to size descriptions for each variety, keeping in mind these are generally managed or pruned sizes, not maximum potential sizes. If you are planting an orchard be sure to include enough space between rows for transporting supplies in and fruit out.

Growing in Containers

Chestnut trees generally grow too large to successfully grow in a container and can outgrow most pots within 2 years.

Do not use soil from your garden to the pot, instead use a potting soil mix with some added compost. For larger pots use a potting mix that has a larger particles in addition to smaller ones.

Care and Maintenance

WATERING YOUR PLANTS

This is the most important and often the most difficult part of successfully growing plants. There are many factors, including the humidity, temperature, soil type, wind, and amount of direct sun that affect how much and how often water should be applied.

A general rule of thumb for plants in the ground is to ensure they receive an inch of water per week over the root zone. An inch of water is equivalent to about ¾ to one gallon per square foot of soil surface area. The typical three foot diameter planting hole would need 7 ½ to 10 gallons of water per week provided by rainfall or by the gardener.

Apply this water once a week, two times per week if soil is fast draining. This will of course depend on your own conditions and the plants you are growing! DO NOT water lightly each day because this results in a wet surface and dry root zone area. The soil should be moist but not soggy to a depth of about a foot for most growing plants. The top inch or two can feel dry, and the plant still bewell watered. The trick is to have the water available where the roots are. In hotter and sunnier areas, a mulch of straw, bark, etc. can greatly ease the burden of summer watering. For plants in containers, water until the soil is saturated and water comes out of the drainage holes. Let the container dry until the soil is dry to the touch 1 to 2 inches down (more deep with deeper pots) and the container is lighter in weight. A plant that has wilted can be receiving either too much or too little water.

In rainy areas like the Pacific Northwest most of the plants that we offer will need relatively little supplemental irrigation ONCE THEY ARE WELL ESTABLISHED in the ground and have had a chance to develop a good root system. However even here it is important to make sure plants have regular, deep watering during the first couple of growing seasons, and the first summer is especially critical. In drier areas, or where soils do not retain water well, permanent irrigation is essential. Remember that you don’t want your trees to just survive, but rather to thrive. Make sure they get the water where they need it, starting at the drip line and extending away from the tree up to several feet ( for older trees) where the feeder roots will be. Drip irrigation and soaker hoses can be an efficient way to deliver the water.

Fertilization

For good steady growth and high productivity, your trees need to have adequate amounts of various mineral nutrients. Some people are fortunate and have naturally rich fertile soil.

Use an all-purpose or balanced fertilizer. A couple of inches of well-rotted compost on the root zone can also be an effective fertilizer. A generous leaf or straw mulch around your trees will not only conserve moisture and help in weed control, but also keeps your soil healthy by building up humus,attracting earthworms, and supporting beneficial fungal organisms. This encourages young trees to be strong, healthy and productive. Avoid applying fertilizer after early summer, doing so can encourage lots of soft new growth that is much more likely to be damaged by winter cold.Excessive use of fertilizer can in-crease disease problems on your plants and can even kill them.

As a general guide, if your tree is producing about one foot of new growth or more a year and has healthy looking foliage, it may not need much or any fertilizer.

Pest and Diseases

Find out what insects and diseases are typical in your area. Ask your local co-operative extension professional what the typical insect and disease issues are in your area. Then you can make selections based on resistance or tolerance information available in our catalog, or, make a plan for controlling problems you can expect with the susceptible varieties you prefer to grow. If you see resistance information about a particular disease for one variety but not another of the same kind of fruit, then that variety may be susceptible or might not have been tested so is unknown. The following are some of the more common issues.

Chestnut Blight

SYMPTOMS

The fungus enters through wounds on susceptible trees and grows in and beneath the bark, eventually killing the cambium all the way round the twig, branch or trunk. The first symptom infection is a small orange-brown area on the tree bark.

CONTROL METHODS

Chestnut blight can also be managed by sanitation practices and chemical control; however, such management strategies are only feasible on a small scale, such as in an orchard. Sanitation practices like the pruning of symptomatic limbs and removal of infected trees can serve to eliminate sources of disease and limit the spread of the pathogen.

COMMENTS

Chestnut blight is uncommon in areas with dry summers. Areas west of the Rocky Mountains are generally considered blight free.

SHOT HOLE BORER

SYMPTOMS

Invades apples, chestnuts, cherries and other trees. Pin size holes in trunk spring or summer. Look close to see sawdust around hole and notice fermented smell. Limbs or whole trees suddenly die.

CONTROL METHODS

No effective chemical organic methods exist currently. Mechanical control can include inserting a stiff wire, like a straightened paperclip, into each hole and forcefully poking to injure or kill the insect within. Repeat within each hole as needed. Whitewash trunk and lower limbs with interior white latex paint diluted 50% with water in fall to confuse beetles next spring. Infestations bad some years. Borers live in alder and other trees.

COMMENTS

Bark beetles sense volatile oils from stressed trees. Keep trees healthy, particularly when newly planted. Monitor and destroy infested trees. Generations occur April-May, June-July and August-September.

Sunscald

SYMPTOMS

Vertical splits in bark appear spring or early summer, usually on the south or east side of the tree. Disease or insect infestations may then occur.

CONTROL METHODS

Whitewash trunk and lower limbs with interior latex paint cut 50/50 with water each fall until bark has thickened. Avoid planting in frost pockets or where water collects in winter.

Comments

Injury occurs during pattern of warm days followed by freezing nights. Sap gets stuck in trunk, freezes, then rapidly thaws in the warm sun the next day, rupturing cells.