Hazelnut

Corylus avellana

These attractive shrubs are notable as the smallest plants to produce a significant commercial nut crop. Because of their compact size they can even be fitted in small gardens.

About Filbert

Hours of winter chill: 500-1000

Size – 10-20 feet x 10-20ft wide

Zone: 5-9

Blooming period: Late winter/early spring

Fruiting period: September – October

Life expectancy: 50 years

Bearing age: 2-4years

Yield: 5-20lb

Spacing: 10-20ft apart

Ease of growing: Filberts are fairly undemanding, but have a major pest in the form of squirrels. If you have squirrels in your area they can make growing filberts quite frustrating (unless you cage the bushes). There is also a significant disease, the Eastern Filbert Blight, though resistant varieties are now available.

Another potential problem is that the flowers appear in late winter and can be damaged by severe cold (-15°F).

Climate: The Filbert thrives in colder conditions than any other commercial nut crop and is an important nut producer in Northern Europe. They actually prefer cool weather and don’t like very hot summers. They have a fairly high chill requirement and can tolerate temperatures as low as -25°F. The flowers appear in late winter and can be damaged by severe cold (-15°F). They grow best in interior Washington and Oregon and may have problems when grown elsewhere.

Soil.

pH 6.5 -7.5

Filberts prefer a deep, fertile, well drained soil that is neutral or slightly alkaline. However they will grow in most soils, even quite poor, rocky ones.

Site

These species will grow in light shade but prefer full sun for a good part of the day. They are quite drought tolerant, but produce better with regular moisture. In nature they grow in the understory layer protected by larger trees. In hot climates they benefit from light shade. If your soil isn’t very well drained you might consider planting on a hillside, or on a mound.

Planting:

In mild climates filberts can be planted at any time from late fall to early spring. In colder climates they are usually planted in spring. As with most other plants a small tree transplants better than a large tree and will do better in the long run.

When you get your plants home it is a good idea to get them in the ground as soon as possible, but if this isn’t possible you should heel them in, which means placing them in a trench (this trench has one vertical side and one at 45 degrees, the trees being laid in at 45 degrees and soil is firmed over them to fill the trench). If you buy plants mail order you should unwrap them immediately and soak the roots in water overnight before planting or heeling in.

How: Dig the planting hole 2‑3 times as wide as the root ball, to give the roots plenty of loose soil to grow into. You want the hole to be the same depth as the root ball (or roots if bare root), so it can be set into the ground at the same depth it was growing in the nursery. This is most easily measured by laying a stick across the hole to get the right height. The graft union should be 3-6” above the soil.

Start planting by throwing a couple of shovels of soil (possibly mixed with some organic matter if the soil is poor – to help it hold moisture) into the bottom of the hole. Make this into a slight mound and then spread the roots out evenly over it. You then put some soil in the hole to anchor the tree in place and firm it down. Then re-fill the hole with the rest of the soil (make sure the tree remains vertical). You may also want to add some rock phosphate to the soil as you go.

When you have finished planting the tree should be on a slight mound, so as the soil settles it becomes flat. If it starts out flat it may end up as a slight depression where water can collect (which can be a problem on poorly drained soils).

You then water the tree thoroughly, not only to supply water to the plant, but also to settle the soil and establish contact between roots and soil.

The final step is to spread out a mulch to conserve water, and keep down weed competition (keep this six inches away from the trunk).

It is also a very good idea to put a permanent label on the tree saying the variety and rootstock (and write it down in your garden journal).

Support: Newly planted trees were once routinely supplied with a stake to support them, but it is now thought that trees become stronger more rapidly if not staked. Staking is only usually necessary on very windy sites (especially for dwarf trees which grow on weak rootstocks).

Protection: If gophers live in your area you will have to plant your trees in gopher wire baskets (I make my own to whatever size I need). If other rodents are a problem (they may chew on the bark, stunting or even killing the tree) you may have to use various kinds of metal or plastic mouse guards. These should go several inches into the ground and should have gravel around them to deter digging.

Maintenance: Filberts are easy to grow if you give them the right conditions, but squirrels can be a major pest.

Mulch: Filberts appreciate a deep mulch of leaf mold or compost. It keeps the ground moist and supplies necessary nutrients.

Fertilizing: Filberts aren’t heavy feeders and if growth is good it isn’t necessary to fertilize (the mulch will supply all they need). If growth is poor you may want to give extra nitrogen in the form of.

Watering: The plants are quite drought tolerant, but for best production you should keep the soil somewhat moist.

Pruning: Filberts are usually trained to grow as shrubs, with several stems, but they can also be trained to grow as trees with one long main trunk. They bear on the previous years wood and once established need little pruning.

Pollination: Filberts are monoecious (the long male catkins and small red female flowers are found on the same plant) and can self-pollinate. However the two kinds of flowers aren’t always open at the same time, so you will get much better fruiting if you plant two varieties. Obviously the male flowers on one must be open at the same time as female flowers on the other.

Flowers are cross-pollinated by the wind and wet or cold winter weather can adversely affect this. They sometimes become alternate bearing.

Propagation: Filbert is fairly easy to grow from fresh (not dried) seed. This can be stratified indoors, though it’s easier to just plant the fresh nuts outside in the fall to stratify naturally. They can also be propagated by separating suckers from the parent plant, layering (bend a branch over and cover it with soil) or root cuttings (each with 2 buds). Improved cultivars may be grafted on to seedling rootstocks.

Pests: Squirrels were born to eat hazelnuts and if there are any in your garden (are any gardens without them?) you won’t get many nuts unless you take precautions. In extreme cases this may have to be a complete cage (this have to be very complete, otherwise these intelligent animals will find a way in).

Birds: Some birds adore the nuts also and they too can be kept out by netting.

Aphids:

Eastern Filbert Blight – This fatal fungal disease can be a serious problem for gardeners in the eastern part of the country. Fortunately newer varieties are immune.

Harvest: The nuts should be left on the plant until they mature fully and fall from the plants. If you pick too early they are okay to eat immediately, but don’t keep for very long. It is essential to pick the fallen nuts promptly otherwise birds, squirrels or other rodents will.

You can tell if a nut is ripe by turning it in the husk, if it moves it is pretty much ripe.

Storage: Dry the nuts in the sun, turning occasionally until the kernel is brittle. They will then store for months in a cool (below 50°F) dry place. The shelled nuts can be frozen for longer storage.

Landscape uses: Filbert is a very attractive, vigorous and densely growing shrub and can be used as a hedge, screen or specimen plant. They sucker vigorously and can grow into dense thickets.

In England Hazel is commonly coppiced to produce long thin poles, which are split and woven into wattle fence panels. These poles can also be used for garden supports and other uses.

Unusual growing ideas: Filbert can be grown as a productive hedge by spacing the plants 4-5ft apart.. They also work well as an understory layer in a forest garden.

Rootstock: Filberts usually grow on their own roots or on seedlings.

Varieties   Food uses Tree Hazel