Growing Cherries

If you’re just planting fruit trees for the first time, also look at the Learn to Grow Fruit Trees page.

Site Selection

• Drainage – Dig a hole 16” deep where you want to plant, preferably in the winter. If water fills the hole and stands in the hole for more than 36 hours, you will need to mound up the planting site. You want to build a 3′-5′ wide mound with 16” to the water level.
• Sunlight – Cherry trees need 6-8 hours of good sunlight. If your site is shady before 4 pm in mid-summer, it is probably too shady to produce good fruit.
• Cherry trees are grafted trees. This means wood of the cherry variety is grafted onto cherry rootstock.
  • What do rootstocks do? Rootstock helps determine tree size when trees are grown and managed to their full potential bearing size.
  • How much room do I need? Trees on smaller rootstocks take less room, but might not bear as much per tree as larger rootstock trees.
  • How high on a ladder do you want to climb? For a sweet cherry on Mazzard you will want a 12′-14′ ladder for pruning, thinning, and harvesting.
  • Tree Spacing – Rootstocks provide a variety of size options. Larger trees need wider spacing, smaller trees can be closer together as they have a smaller root system and compete less with neighboring trees for water and nutrients.
    • On Gisela 5 rootstock, space the trees 8′-10′ apart. A free-standing sweet cherry on Gisela 5 can be managed at a height of 9′-10′. Tart cherries can be managed at 8′ on Gisela 5.
    • On Krymsk 6 rootstock, space the trees 9′-12′ apart. A free-standing sweet cherry on Krymsk 6 can be managed at a height of 10′-12′. Tart cherries are incompatible with Krymsk 6.
    • On Krymsk 5 rootstock, space the trees 10′-15′ apart. A free-standing sweet cherry on Krymsk 5 can be managed at a height of 12′-15′ Tart cherries can be managed at 10′.
    • On Mazzard rootstock, space the trees 15′ apart. A free standing sweet cherry on Mazzard will grow to 15′-20′. Tart cherries will grow to 12′-15′.
  • Pollination– All fruit trees need to have a pollinating insect move pollen to the anthers of their flowers for that flower to become a fruit. There are several varieties of sweet cherry that are self-fertile, where the pollen from the flower of that tree moved to the anthers of the same tree will cause fruit set. For sweet cherries that are not self-fertile, another sweet cherry that blooms at the same time is needed to provide the pollen for fruit set. Tart cherries are also self-fertile, but bloom too late to pollinate sweet cherries.

Planting Requirements: Are you ready to take care of your trees? If you’re bringing home bare root trees, you want to be able to plant right away.

• You can plant if your soil isn’t too wet to work and you can dig holes directly.
• Mound the soil if needed to keep roots above the winter high water table.
• For bare-root trees:
  • When planting, be sure to keep the graft union 2″-4″ above soil line.
  • Prune off broken roots, spread out over soil mound built in the bottom of the hole.
• For potted trees:
  • Water the pot so the soil in the pot is moist.
  • Remove the pot and use your fingers or a garden claw to rough up the roots. During the dormant season, you can wash some of the potting soil off the roots before planting.
  • Plant the tree the same depth it was in the pot. Be sure not to bury the graft!
• For either bare-root or potted trees:
  • Water trees in to settle the soil after planting.
  • Have a plan for watering during the summer:
    • Young trees need consistent soil moisture during their establishment.
    • During the summer, check the soil often to make sure it is moist to a depth of 6”-8”. How do you check?
    • 24 hours after watering, dig a 6″-8″ deep hole near the tree and check for dampness. If the soil is not moist to that depth, you did not water enough.
  • Plan to stake your trees at planting – even semi-dwarf trees need staking the first year. We live in a windy area. New trees do not yet have big enough root systems to stand up to strong winds. Use a round stake and stretchable material for tying to minimize bark damage.

Fertilizer and lime (for more detail see Nutrition section below)

• Young fruit trees benefit from fertilizer throughout the first 3 years to stimulate growth. Use a fertilizer formulated for fruit trees for the best results. In sandy or gravelly soils, they may need fertilizer past 3 years.
• Western WA soils are typically acidic, and fruit trees prefer a neutral pH (6.0-7.5). If the soil pH is below 6.0, your tree may not be able to utilize nutrients that are present. Liming at planting and annually in the fall will help sweeten the soil (raise the pH) and provide calcium for good fruit.

Year 1 Post Planting

• Keep soil moist and keep a weed-free area 3’-4’ in diameter. Weeds compete for moisture and provide cover for field mice, which may stunt or potentially kill young trees by nibbling bark and roots.
• Insects and disease – watch for problems on your young trees. Most pests and diseases aren’t hard to manage in the first 2 years (see Disease and Pest Management section).
• If new growth shoots (terminal shoots) stop growing by early summer, it is usually one of three things: not enough water, fungal disease, or deficient nutrients. Lime and compost additions in years 1 and 2 can help.
• Remove all but 2-4 fruit clusters in the first year. This helps put the tree’s energy into growing wood and roots.

Years 2-3

• Prune cherries (section below) after bloom or after harvest. Only prune when there are at least 48 hours of dry weather following the pruning work. This allows the pruning cut to naturally seal over, lessening the risk of rain and wind spread bacterial infection.
• New growth – if shoots grow less than 18” average each year, the tree might be lacking water and/or nutrients.
• Keep 3′-4′ area clean around trees for the first 7-8 years.
• Water- Trees will need 1” of water per week in the growing season in average soil, either from rainfall or irrigation. Heavier soils may need less water, sandy soils more water.
• Check the soil moisture level to make sure you are watering enough: 24 hours after watering, dig 6”-8” down and make sure soil is moist.

Fruit Tree Nutrition and Water

To understand the needs of fruit trees, it is necessary to understand our climate patterns and our soils in Western Washington. The maritime Pacific Northwest is known for being rainy, but most of our rain falls between October and June. Our summers are typically dry. Our soils also tend to be high in organic matter. High organic matter combined with a rainy environment can cause our local soils to be acidic, with pH ranges below 6.0. Have your soil tested to determine both pH and nutrient availability. If you are planting your trees into imported (manufactured) soil, ask the company if they have a soil test that will provide you information on pH and nutrient values of the mix.

Ideally, a range of 6.0 to 7.5 is optimal for orchards. In general, the availability of micronutrients is lower in alkaline (high pH) soils. Nutrients such as iron and zinc may not be in a form available to plants. In contrast, phosphorus may become limiting in acidic soils. Also, in acidic soils, aluminum can become available, which is not a nutrient and is toxic to plants in high concentrations. At pH 6 and higher, very little aluminum is in solution.

Additionally, soil pH affects the abundance of microorganisms. Bacteria are generally more prevalent in alkaline soils and fungi dominate in acidic soils. This is important because microbes are responsible for the cycling of nutrients. The most diverse and numerous populations are found in near-neutral soils. Furthermore, soil pH influences pathogenic microbes, and growers can adjust pH to manage some plant diseases.

Low pH soils (5 and lower) can result in:

• calcium (Ca) and magnesium (Mg) deficiencies;
• restricted root growth or regeneration due to aluminum (Al) toxicity;
• reduced availability of Phosphorus (P);
• reduced efficiency of Nitrogen (N) and Potassium (K) use and poor response to N and K fertilizers.

Acidic soils may be neutralized over time with the application of lime. The amount of lime needed to bring the pH to nearly neutral depends on the buffering capacity of the soil and how much the pH needs to be adjusted. The higher the amount of clay and organic matter, the higher the buffering capacity and more lime needed. There are many sources of lime available. Dolomite lime also contains magnesium as well as calcium but is slower acting than agricultural lime (calcium carbonate). This all sounds complicated, but the takeaway message is that applying lime annually to your orchard in the fall will help your fruit trees thrive.

Fertilizers

Young trees (first 3 years) can benefit from added fertilizers (unless your soil tests high in nutrients). Nitrogen (N) stimulates vegetative growth, but too much can lead to excessive, weak growth. Phosphorus (P) encourages root growth. Potassium (K) helps flower buds form, and in bearing trees, can help produce higher quality fruit.

Use a fertilizer formulated for woody plants or fruit trees. Conventional fertilizers for fruit trees usually have a formulation with lower nitrogen and higher phosphorus and potassium ratios. For many years, we have had a local farm company blend a conventional fertilizer formulated for local soils, with NPK values of 8-18-18. This fertilizer also has micronutrients incorporated (zinc, boron, manganese). There are other good fertilizers out there, including organic fertilizers. There is a chicken manure fertilizer, Nutri-rich 4-3-2, that has added calcium, and has proven to be locally a good all-purpose fertilizer for both young fruit trees and vegetable gardens.

Apply conventional fertilizers in spring just as new growth starts, usually mid-March. A second application can happen in late May, and a third in early July (the ‘holiday’ method of remembering: fertilize on St. Patrick’s Day, Memorial Day, and 4th of July). Organic fertilizers break down more slowly than conventional ones, so one application in early March followed by one in early June is usually adequate. Follow the directions on the package to calculate how much to apply. When in doubt, always apply less than you think you need rather than more – you can damage your tree by applying too much!

Water

Young fruit trees cannot tolerate drought. Even established trees need summer moisture to produce quality fruit. Because we cannot count on summer rain, growing fruit trees means watering. How much should you water? There is no easy answer, as it will depend on your soil. Sandy soil will hold less water than silt or clay rich soils, so may need more frequent watering. Moisture retentive soils high in clay will need less frequent watering in general.

Technical Alert! An interesting tool to explore is the Web Soil Survey. This online tool maps soils and provides data about those soils. You can enter your address and find out about your native soils, including the water storage capacity of the soil (in the top 60 inches of soil). This is a measurement of how much plant-available water the soil can store between soaking rainfalls. For instance, just north of Bellingham is an area of silt loams, including the Whatcom-LaBounty silt loams and Yelm silt loams. These soils have a water storage capacity of 12.7-16 inches (when the soil depth is 60 inches or more). These soils theoretically can provide plants with up to 16 inches of water during dry periods (in reality, not all of that water is available). If you use the ‘plants need 1 inch of water per week’ rule of thumb, the Yelm silt loam theoretically has a potential of unirrigated plant support for 12-16 weeks. In contrast, part of the main Cloud Mountain farm is made up of Kline sandy-gravelly loam, with a water storage capacity of 3.4 inches. Fruit trees planted here need irrigation in summer to thrive.

So, how can you tell if your soil has enough moisture beyond the theoretical? If it has been rainless for a week or more, dig a hole to check soil moisture. The soil around your fruit trees should be damp to a depth of 6”-8”. If you’ve recently watered, wait 24 hours, then dig the test hole. If your soil is not damp, your tree needs more water. After a few times, you should begin to get a sense of how much you need to water to get that soil damp to that depth.

See our Disease & Pest Management for the Home Orchard page for general fruit tree management

Pest and Disease Management

Sweet and tart cherries are prone to several diseases and can be attacked by several insect pests as well. Most diseases can be prevented by careful site selection (low chance of late spring frost) and a proactive control program.

Diseases

• The most serious disease of cherries is bacterial canker. This disease results when the Pseudomonas syringae bacteria enters wounds caused by injury, dormant season pruning cuts, or spring frost damage. The bacteria creates cankers in the bark and can cause branch dieback as the canker girdles the branch. A delayed dormant spray at bud stage 3 of copper plus horticultural oil can help protect the tree from infections of frost-damaged tissue. Another spray of copper should be done at leaf fall to prevent cankers in winter-injured tissues.
• A second common disease of cherries is blossom blight or brown rot. This fungal disease can cause blossoms to wither and drop, and can cause buds to die creating blank wood or cause the fruit to rot before ripening. A spray of micronized or wettable sulfur during bloom can help prevent the disease from infecting the blossoms. After bloom, Serenade Garden or Monterey Complete Disease Control spray can also help prevent the advancement of the disease.

Pests

• A common pest seen on young cherries is Cherry Slug. This pest, also seen on pears, is the larvae of a sawfly. The slug-like larvae chew the upper leaf surface. There can be 2 generations of this pest. The most serious generation is the first generation, which can appear in June. The larvae can cause enough leaf damage to decrease photosynthesis in the tree. Pick off the larvae. The leaves can also be dusted with diatamaceous earth, and neem based sprays can also be effective.
• Like many fruit trees, cherry trees can be host to leafrollers. These moth larvae eat the leaves and can cause distortion. A delayed dormant spray at bud stage 3 containing oil can smother pupae that overwinter in cracks in the bark. A spray of Bt (Bacillius thuringiensis) at bloom can also help control populations.
  

  Spotted wing drosophila

• A serious problem in cherries can be spotted wing drosophila, an invasive fruit fly that only appeared in the US in 2009. If you are finding small stings on the fruit, and when broken open the fruit contains a small white larvae, that is the larvae of the SWD. Some steps to control this pest:
  • Clean up all fallen fruit as it drops. Remove cherries from the tree if appears to be infested;
  • Monitor for SWD with vinegar traps. Learn to identify the flies (other fruit flies will also be attracted to the traps);
  • Spray the trees with kaolin clay (Surround) before the fruit starts to change color to hide the fruit from the flies or;
  • Spray the trees with a peracetic acid fungicide (ZeoTol, BioSafe Disease Control, Oxidate) as the fruit starts to change color. This removes the yeast film on the surface of the fruit and hides it from the flies.
  • Spray with a product containing Spinosad to kill the flies. There is about a 5-7 day residual action. Do not use spinosad more than 3 times per year to prevent the flies from becoming resistant.

Pruning & Training

There are many ways of pruning and training both sweet and sour cherries. We’re highlighting two systems that have worked well for our region.

Download a pdf of Spanish Bush Training system

Spanish Bush Style

This system for training cherries works for both sweet and tart cherries on dwarfing rootstocks. Tart cherries are less vigorous and less upright than sweet cherries, so mature trees will be smaller. When pruning all cherries, it is best to wait for dry weather (48 hours after cuts are made is ideal) to reduce disease. Ideally, prune after bloom or after harvest for best results.

At Planting

If the tree is an unbranched whip, between bud break and bloom, head it back to 20″-30″ above the ground. Spread the developing branches to form wide crotch angles. Allow these primary branches to grow 20″-24″ in length, then head them back all at the same level, which should be about 6″ higher than the cut made at planting.

If the tree at planting time already has good branches (ideally, 3 or 4 evenly spaced branches around the tree), at bud break, head the branches back so their tips are all the same level at 10″-12″ long.

Second Spring

When the secondary branches have reached 20″-24″ long, head them back to 10″, making the cuts all at the same level.  Ideally, these cuts will be made near or after bloom time. When the tertiary branches reach 20″-24″ in length later this spring, head them back to 10″ above the previous cut, again making all the cuts at the same level. These third training cuts may only be necessary on more vigorous varieties. You may need to thin some branches out for good light penetration.  Thin by removing vigorous, upright branches, leaving weaker, more horizontal branches to encourage fruiting.

As the Tree Matures

The secondary and tertiary branches become the scaffold branches in the tree.  The fruit develops on weaker wood growing from these branches, and must be renewed on a regular basis. Stub back about a quarter of the fruiting wood each year after the fruit is harvested. Thin vigorous upright branches to maintain light penetration. In the autumn, top the trees at 8′.

 

 

 

 

 

 

 

Download a pdf on Upright Fruiting Offshoot Training

Upright Fruiting Offshoot (UFO) Sweet Cherry Training

Another very good training and pruning system for sweet cherries on dwarf rootstock is the Upright Fruiting Offshoot (UFO) system. Sour cherries are better trained to the Spanish Bush System. The Upright Fruiting Offshoots (UFO) system for sweet cherries was developed to:

• Simplify training, pruning, and crop-load management;
• Utilize the sweet cherry’s natural upright growth habit and manage vigor by establishing multiple vertical structural fruiting units;
• Achieve high, uniform light distribution to fruiting branches.

At maturity, the UFO system yields a fruiting wall that is precocious, productive, and simple to maintain. Each tree is comprised of a permanent single horizontal trunk from which renewable fruiting shoots are grown vertically. Fruit are borne predominantly on spurs but also at the base of 1-year-old shoots, all on vertical wood. The UFO system is most easily configured to a single vertical plane, requiring trellising (about five wires). UFO training may be used to establish a pedestrian orchard where very short ladders are needed or none at all, though higher yields in the single vertical wall UFO can be achieved by maintaining a tree height of 12′-15′. Establishing the UFO system is straightforward with little to no pruning required at planting.

Spacing:

• Space rows 9′-10′ apart;
• In the row, space trees 5′-6′ apart (Gisela 5 Rootstock);
• Trellis should be at least 5 wires, lowest wire at 20″, then spaced every 18″-20.”

At planting

• Unheaded and unbranched (whip) trees are recommended.
• Plant trees at a 45-degree angle pointing the terminal to the south. This reduces the potential for sunburn on the trunk during establishment. Important: do not plant the trees vertically and bend them to a 45-degree angle.
• Clip/tie the trunk where it intersects the lowest wire (20 inches above ground) to maintain the planting angle. There is a single lowest wire in the UFO trellis.
• Remove any nursery tree branches with thinning cuts so you have an unbranched whip for planting.
• Manually rub off all buds below the first trellis wire.
• Score the bark with a coarse saw blade above upper buds about every 8″ to stimulate vertical shoot formation.

First growing season

• Remove any shoots that form below the first trellis wire. In late spring, evaluate growth uniformity of vertical shoots; head any excessively strong shoots to a stub of no more than 2″ with several leaves to promote regrowth of each as new dual shoots to be more in balance with the existing moderate shoots.
• Once new shoots at the terminal end are 12 inches or longer, train trees to the lowest wire by removing the initial clip and placing it further along the trunk so that the orientation is slightly above horizontal.

First dormant season

• Thin out weakest or most vigorous shoots if density exceeds one per approximately 8-10 inches per plane. Keep all shoots growing at the same vertical elevation as much as possible.
• Where possible, clip or tie shoots to the second wire.
• Using thinning cuts, remove any shoots growing below horizontal from the main leader.

Second growing season

• Where gaps on the horizontal trunk exist, score above upper-facing buds to promote completion of vertical shoot formation.
• Tie or clip upright shoots to successive vertical trellis wires as growth allows.
• Using thinning cuts, remove any new shoots from below the first trellis wire.
• In late spring, evaluate growth uniformity of new vertical shoots and head any excessively strong shoots to a stub of no more than 2″ with several leaves to promote regrowth of each as new dual shoots to be more in balance with the existing moderate shoots.
• In mid-summer, remove excessively vigorous uprights with a thinning cut.
• Thin out weakest or most vigorous leaders if density exceeds one per ~8″.
• For highly productive varieties, remove all lateral shoots on upright leaders with thinning cuts. On moderately productive varieties, remove all lateral shoots on upright leaders with stub cuts (i.e., leaving three to seven buds at the base of the lateral shoots for additional fruiting). NOTE: this removal of lateral shoots also can be done by summer hedging about 4 to 6 weeks after harvest.
• Tie or clip upright shoots to wires.
  

  Established cherry wall.

Other Management of the Orchard

Cherries on dwarfing rootstocks have a tendency to flower very heavily. This can cause the trees to overset their fruit. In years this happens, you will need to thin the fruit. There are two methods for thinning. One is to manually remove fruits after they start to grow. This can be done by clipping through the stems of the clusters of fruit. It is best to remove the fruit from the bottoms of the limbs and branches to create more air space around the remaining fruit. This thinning can even happen before the fruits start when the tree is still in bloom.