Selected Clippings on Care and Maintenance of American Chestnut from The Canadian Chestnut Council's Newsletter

Seed Production and Nut Harvesting (No. 9, April 1994)

A major limiting factor in getting more American chestnuts planted in Ontario is the scarcity of seed. A second big problem is gathering the limited amount of seed produced.

The chestnut tree requires cross-pollination for a good set of seeds. Every tree contains male and female flowers. On the bisexual catkins, the male flowers open and shed their pollen before the female flowers at the base of the catkins are ready for pollination. This seems to be nature's way of favouring cross pollination from another tree. Because many of the large healthy chestnuts in Ontario are often single specimens, cross pollination does not readily occur. Even so, however, several single trees have been found to produce a variable amount of seed each autumn.

Harvesting the nuts is also a difficult problem. Squirrels, blue jays, etc., are aware when the burrs begin to open and are always anxious to help with the harvest. In a Virginia Cooperator's Foundation project, the nut crop has been taken for the last nine years by cutting the largest burrs off the trees as soon as the first ones open. Removing the nuts from the burrs later is difficult, but it ensures a full harvest. In Ontario, nut gatherers often visit the trees daily, in early morning, to pick any fallen nuts off the ground. Know your tree and, by keeping a daily watch, efforts may pay off.

Blossoming and Harvesting (No. 7, September 1993)

The nut harvest will begin in late September and continue through the first week in October. Because of the prevalent high summer temperatures and adequate moisture conditions, nut fall may begin a few days earlier than usual. Most of the nut harvest in October will be from single blight-free trees which because of a lack of cross-pollination will probably produce only a few mature seeds. In the past, however, a few of these single trees have produced as many as 100 to 150 or more plump seeds. Burrs with immature seeds occasionally open as early as September 20th. Mature seeds are obtained from burrs opening later, often in early October. Plump seeds are usually found in burrs at the top of the tree and out at the ends of branches.

The presence of `noisy' blue jays around the trees usually tells us that the nut harvest is on. A daily, early morning search for nuts among the fuller leaves near the base of the tree is usually most rewarding. A search is particularly advisable after a high wind has shaken nuts from partially opened burrs.

Nut Storage (No. 7, September 1993)

Leaving the harvested nuts to ripen for one week to ten days on a garage bench secure from squirrels and other predators is advisable. Then they should be enclosed within one or two plastic bags and stored in the refrigerator for the winter. Embedded in a small amount of barely moist peat moss, the nuts will retain their germinality. The nut package should be inspected every month or so to ensure that they have not molded. Moldy nuts may be washed in water to remove the mold, then dried for a few minutes and stored again in clean containers.

Nut Germination and Planting (No. 7, September 1993)

Chestnuts stored under proper storage conditions don't usually start to germinate until March or early April. Sprouted nuts may be planted in containers (one-litre milk cartons are ideal) in field soil. Sandy soils such as are found in tobacco fields are ideal. A soil mixture like the following is also excellent:

* 2 parts sandy field soil
* 1 part peat moss
* 1 part vermiculite

Containers must have holes in the bottom to allow excess water to drain out.

Nuts may be planted in a cold frame in the autumn before the ground freezes. They should be planted about 3/4 inch below the surface of the soil. Outdoor beds should be covered with a layer of straw or leaves to a depth of at least six inches to keep the soil below from freezing. Of course, all outdoor plantings must be screened with metal mesh wire to exclude rodents.

Chestnut Seed Preparation and Treatment for Germination (No. 1, February 1990)

When collecting seeds, it is important to understand that they are perishable and should be air dried (in a cool, shaded location) for no more than a few days to a week. Next, they should either be 1) fall planted in a prepared seedbed (protected from predation and deep freezing), or 2) placed in a moist, peat/sand medium, refrigerated, and then planted in the spring, or seeds showing early germination in storage should be planted indoors. Chestnuts do best in sandy, well drained soil. On heavier soils, such as Guelph's clay-loams, they soon become chlorotic and weak, thus such soil conditions are not recommended for this species, even though the Chinese chestnut will tolerate them.

Seed Stratification and Growth of Seedlings (No. 2, April 1991)

Many of you have collected nuts that have been stratified over winter, ready for spring planting. What now? If they have been kept at the right temperature and moisture level, they are likely beginning to germinate. When a root begins to emerge from the nut, it is time to plant them in soil. For indoor plantings, the nut should be placed about one cm below the surface in sandy soil. Containers such as one-litre milk cartons are suitable, as long as good drainage is provided by puncturing the bottom. At room temperature the germinating sprout will appear above ground in a week or two. Once the seedling is above ground, the container should be kept in an area exposed to adequate natural light, such as a windowsill, with watering as for household plants.

When the danger of frost is past, the young seedling may be set outside, first in a shaded location to prevent leaf scorch. If growing in a degradable container, only the bottom needs to be removed. Protection of seedlings from rodents and deer is a must. Place a mesh wire cage around the young tree, extending it below the soil surface to prevent squirrels or chipmunks from foraging for the nut still attached to the seedling.

If large numbers of seeds are available for nursery-type plantings, the germinating nuts may be planted directly in the field by April in southwestern Ontario. A mulch of straw or leaves is advisable to protect the germinating seedlings, and of course, field plantings must be covered with wire mesh to prevent rodent damage.

Storing Chestnuts for Propagation (No. 4, September 1992)

American chestnut seeds will not germinate if 50% of their moisture is lost. Thus, harvested nuts should not remain on a garage bench or a kitchen counter for more than a week. They should then be placed in a plastic bag to prevent further drying, and stored in the crisper section of a household refrigerator. A small amount of slightly moist (not wet) peat moss should be enclosed with the nuts. Properly stored nuts often start to germinate in the refrigerator in March or April. If handled with care the germinated and ungerminated nuts can be planted directly into the field in beds protected against squirrels, or indoors in cartons (e.g. one-litre milk cartons) of sandy garden soil, given natural light from a southern exposure. Germinating nuts require only a minimum of moisture. Don't over water.

New Plantings (Culture and Care) (No. 9, April 1994)

Chestnut seedlings that have been started indoors should not be set out until the danger of frost is past. Tender plants should be hardened off by a gradual exposure to the elements. Even if new leaves are nipped by a late frost, the chestnut seedling will leaf out again.

Remember that chestnuts like a sandy or coarse-textured, well-drained soil. They thrive on abundant moisture, but will not tolerate `wet feet'. Several of the new plantings of recent years have suffered from inadequate moisture. After a summer dormancy brought on by extreme drought the chestnut seedling makes little or no growth for the remainder of the growing season.

Clean cultivation is advised. In the first and second years of outplanting do not allow grasses or weeds to grow with 15-18 inches of the seedling.

Tree shelters are helpful. The greenhouse effect accelerates growth. They also prevent browsing of the foliage by deer and other wildlife. If commercial plastic shelters are used, cover the open top with wire mesh or cheesecloth to prevent small songbirds from becoming trapped inside.

Fertilization: Unless you are an experienced grower, fertilization in the first year is not advised. In subsequent years, a complete fertilizer like 10-10-10 may be applied. Best results are obtained by applying a teaspoonful to the bottom of a 12-inch deep hole punctured in the soil at the drip line of the outer branches. Five points of application should be adequate for a two-year-old seedling. As the sapling grows more points of application can be used and made at greater distances from the trunk. Do not fertilize after July 1st. If the soil is dry, fill the fertilized holes with water once or twice.

New Plantings (Old and New Areas) (No. 10, October 1994)

Because the blight is still active at several sites in the counties bordering on or near Lake Erie, where chestnut trees existed in pre-blight times, CCC has attempted to keep new plantings in this zone to a few seedlings. Growers are advised to keep new plantings at least 600 metres away from known blight sites. Other plantings have been made to the north and east (new areas). Chestnut seedlings planted in 1990-1993 on a sandy loam site in Dufferin county survived the severe chill of last winter very well. Test plantings in a few counties as far east as Frontenac near Lake Ontario show promise of good survival. Reports of the growth of the Ottawa planting (1976) are also favourable.

The importance of good care of seedling plantings cannot be stressed too much. As with most forest tree species the average grower has much to learn about the growth and care of chestnut during its first 3-4 years. Part of the program of the upcoming annual meeting will address itself to this subject. If well-drained sandy soil conditions are met, the next most critical need is the availability of moisture. A young chestnut could use up to a gallon of water every 4 or 5 days during July when growth is fastest. Young chestnut trees do not compete well against grasses and weeds until they reach a height of 1.5-2 metres. 

Transplanting and Watering (No. 3, April 1992)

The planting hole should be twice the size and depth of the root system. Fill in around the roots with a mix of 1 part compost or peat moss to 3 or 4 parts of soil. Water transplants immediately after setting. During dry periods, the soil around the roots should be watered once a week.

Transplanting Shock (No. 11, April 1995)

Why do some seedlings do well and other fail to grow for 1 or 2 years? This question is often encountered and a bit of research has enabled us to give the following answer.

Any transplant, woody or herbaceous, suffers from the shock of a move. Bare-rooted transplants suffer most. Transplants of an herbaceous type, like tomatoes, peppers, spanish onions, tobacco, etc., suffer less than most woody types. Transplanted tree seedlings may suffer serious injury because the complex relationship involving "mycorrhiza" (that mass of fungi that cluster around the roots) has been disturbed. When these fungi are torn loose from the tree's roots they require time and favorable conditions to re-establish themselves. Many of the essential elements (minerals) enter the tree's roots via the mycorrhizal fungi. If these fungi are destroyed, the tree will find it difficult to survive. To reduce the shock of transplant injury, do not allow the seedling to starve for water. Keep the growth of grasses and weeds at least 12 inches away from the tree stem. Keep the soil around the roots moist by frequent watering (once a week during July and August). A deep mulch of wood chips, sawdust, straw, etc., is also of great benefit in preserving moisture.

Once a tree seedling is forced into a summer dormancy because of dry soil, it seldom starts regrowth until late in the growing season. New growth in chestnut late in the season usually results in a soft growth that does not harden off and thus becomes prone to winter injury.

Watering of Seedlings in First Year (No. 6, May 1993)

When seeded directly, the American chestnut produces a long tap root which is often 24 inches (60 cm) long when the above-ground growth may not be more than 8 or 9 inches (20-24 cm). Consequently, it is understandable that seedlings started in one-litre cartons or similar containers will profit from a few timely waterings in the first year after transplanting.

Fertilization and Weed Control (No. 6, May 1993)

Chestnut plantings profit from a light application of a commercial fertilizer (10-10-10) starting in their second year. Best results are obtained by applying the fertilizer in holes punched into the soil to a depth of 10 inches (25 cm) but no closer than 12 inches (30 cm) from the tree trunk. A teaspoon of fertilizer at four sites around the tree should be adequate for a 3 foot (1 m) high tree. For each subsequent year of growth the amount of fertilizer may be increased and spaced farther out from the trunk.

Chestnuts grow best if no grass or weeds are allowed to grow within a radius of 1-1.5 feet (30-45 cm) of the trunk for the first 2 or 3 years.

Fertilizing Chestnut Seedlings (No. 3, April 1992)

The American chestnut does best on a well drained, somewhat acid soil, similar in soil preference to blueberries and azaleas. At a soil pH above 6.5 nitrogen is frequently limitiing.

Transplants may be injured or set back if fertilized in their first year. After being in the ground for a year, the new seedlings usually respond well to light applications of a balanced fertilizer, such as 10-10-10 or 7-7-7. As a general rule, apply 1/2 kg (about 1 lb) of granular fertilizer per inch of trunk diameter; one half in early spring and the other half in early July. Apply the fertilizer over the root zone, 15 cm (6 inches) away from the base of the trunk, to the ends of the branches.

Use of Tubex and Plastic Shelters (No. 10, October 1994)

A number of growers have been experimenting with plastic tree shelters to give greater protection to new seedlings and young trees. Shelters about one metre or so high seem to offer the best promise. On average, it requires about two growing seasons until the seedlings have grown out of the tops of the shelter.

In September and early October, the shelters should be elevated 5-7 cm above the soil line to provide a chimney draft that encourages the proper hardening-off of the tissues before winter. After leaf drop and before the soil freezes the shelters should be lowered again and buried in the soil to prevent rodent injury to the lower stem. Shelters prevent a certain amount of deer browsing.

Protection of Young Trees (No. 7, September 1993)

Plastic (Tubex) protectors (1.3 and 1.6 metres high) usually work well in protecting field plantings. The tubes act like miniature greenhouses and protect seedling trees from deer browsing, until the trees grow out of the top. Last winter in one planting in the Niagara area mice or voles burrowed through the base of the tubex protector and girdled the stems. It is advisable to check on all plantings periodically for rodent and other damage.

If plastic tubes have not been used, young trees should be protected in the autumn after dormancy by tree guards such as are used in fruit orchards to prevent deer and vermin damage during the winter. Sprays to deter rabbit and deer feeding may also be applied.

Pruning (No. 11, April 1995)

Where the chestnut tree is being grown and what type of tree form is desired will determine whether pruning is required. If a tall timber tree is the objective, it would be well to prune off the lower branches in the third or fourth year. If a good nut-bearing tree growing in the open is wanted, little or no pruning may be necessary. Eventually, the lower branches die, if the exposure to sunlight becomes a limiting factor. Chestnut sometimes produced double or triple stemmed trees. These may be undesirable and 1 or 2 stems may be removed when pruning.

Cold Hardiness (No. 7, September 1993)

The American chestnut has been found to be more cold tolerant than formerly thought. A 17-year-old planting of eight trees at Ottawa has done well. We have also verified the existence of American chestnut trees growing near Huntsville, Ontario. The largest tree is 50 feet high and has a trunk diameter of about nine inches at breast height. There are two smaller sprouts, 3 and 7 feet high, about 100 feet away. The big tree is producing burrs that may contain plump nuts.

In addition to the new plantings within the old chestnut belt in southwestern Ontario, new plantings in the counties of Dufferin, Victoria, Hastings, Frontenac and Prince Edward have been established. Two trees in a four-year-old planting in Dufferin county are 9 feet high. Most are in the 2-5 foot range.

This year the late season frosts in May and June damaged the opening buds in several chestnut plantings of southern Ontario. Despite the frost damage recovery was quite rapid and by September the terminal growth on two- and three-year-old plants ranged from 1.5-2.0 feet or more.

Special Note:

Although several of these clippings recommend storage of nuts in the refrigerator within slightly-moistened peat moss, I find that storage of the nuts in plastic bags alone to be much more effective - especially at reducing the amount of storage molds that develop on nuts stored in peat moss. The plastic bag should be mostly closed but with a small opening left to exchange moisture and air.  (G.J. Boland, 1996).