growing chestnut trees
A chestnut is the edible nut of the chestnut fruit, produced by the chestnut tree (Castanea sativa, Castanea dentata, Castanea mollissima). Chestnuts are native to the Mediterranean areas of Europe, China, and North American continent. Chestnut trees are cultivated all over the world, though in North America all American and European varieties cannot be grown east of the Rocky Mountains due to chestnut blight. Chinese varieties have some blight resistance. Due to this it is important to choose one that is right for your area.
Choosing a Variety
European and American Chestnuts grow to about 40‘ tall and 40‘ wide, Chinese chestnuts are a little smaller growing to 35’ tall and wide.
Orchard plantings can be planted initially at 20’ spacing, then thinned to 40’ when the leaf canopy closes.
Unless otherwise noted, all chestnuts need another variety of chestnut nearby to pollinate each other. In addition, some are better pollenizers than others.The pollenizers should be planted no further than the wind will carry the pollen to ensure proper cross-pollination, up to 200’.
Nuts are ready to harvest in fall, when the spiny husks start to split. Seedling trees need 5-7 years to start producing, grafted trees 2-3 years to start producing.
USDA Hardiness Zone
Chestnuts are hardy to USDA zones 5-9. This rating tells you the minimum winter temperature the plants typically survive when properly hardened off. On our web site you will find a USDA Hardiness Maps link which provides information on the average minimum winter temperature in your location, by zip code.
Many plants native to locations that have cold winters have a Chill Hour requirement to ensure uniform waking up of flower and leaf buds in the spring. The chill hour requirement of plants varies by species, by cultivar, and sometimes by the level of dormancy achieved.
Where to Plant Your Tree
Chestnuts 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 fruit. Fruit ripening and flavor development are also benefited by the carbohydrate production stimulated by the sun, as well as it’s heat.
Chestnuts tolerate a wide variety of soils so long as they are well drained, do not flood in winter, 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
Chestnuts are not good candidates for growing in containers for more than a few years.
Do not use soil from your garden in the pot, instead use a potting soil mix with some added compost. For larger pots use a potting mix that has larger particles in addition to the smaller.
Care and Maintenance
Watering Your Tree
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 be well 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 1-2 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.
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. Many soils, however, are deficient in some nutrient or another and use of fertilizers, organic or chemical, can be highly beneficial if you want your trees to grow well. If you have a large garden or orchard it can be well worth it to have your soil analyzed by a qualified laboratory so you know for sure just what your soil needs. Typically this might cost $30-$60, depending on how detailed an analysis you want. Unless you know what is available in your soil, you will not be able to supplement it properly.
Use an all-purpose or balanced fertilizer like the organic fruit tree and shrub 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. Use of concentrated products like chemical fertilizers or strong organics (for instance blood meal) is usually done from late winter through early summer. Applying fertilizer after early summer 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. Use of too much fertilizer, whether chemical or organic, can contribute to stream and groundwater pollution, so please try not to use more than your trees really need. 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.
Pests 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.
Shot Hole Borer
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.
No effective organic methods. 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.
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.
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.
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.
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.