A reader recently asked me why their pear tree isn’t growing new leaves this season. While I had an idea, I looked at the photos they sent me and did more research to find out more. Here’s what I found.
Pear trees commonly won’t grow new leaves due to improper watering, climate, and nutrients, as well as transplant shock, pests, and diseases. For best results, only water when the top 2-4 inches of soil is dry, provide compost or fertilizer, and inspect the leaves for any signs of pests or diseases.
So, while pear trees won’t grow for several reasons, how can we tell what the issue is, and from there—how can we fix it? Let’s take a closer look.
1. Improper Watering
The best way to water pear trees is to only water when the top 2-4 inches of soil is dry.
I check this with the “Finger Test”, by pushing my finger into the soil, under the tree’s canopy. If the soil is wet, hold off on watering. If it’s bone dry, water it.
The goal is to have soil moisture similar to a wrung-out sponge.
However, there are times when the pear tree’s soil is holding too little or too much moisture. In this case, we’ll need to do more than the finger test.
Under-Watering
If you find your pear tree’s soil is drying within a matter of hours of watering, it’s likely draining too fast. Common symptoms of under-watered pear trees are leaves curling, drying, browning, and dropping.
Here’s how to fix soil that’s draining too quickly:
- Provide 2 inches of compost every 1-2 months. The benefits of compost include greatly increased water retention, essential nutrients, and promotes beneficial soil life such as earthworms.
- Apply 4-12 inches of mulch. Benefits of mulching include dramatically decreased evaporation, regulation of soil temperature, and erosion prevention. Use mulches such as bark, straw, leaves, and pine needles.
For more context, every 1% increase in the soil’s organic matter (compost) leads to an additional 20,000 gallons of water per acre.
For potted pear trees, also apply the 2 inches of compost. I do still recommend providing mulch around the base, but you may have to use less depending on how much room is left in the pot.
Over-Watering
You can tell if your pear tree is over-watered if its soil is staying sopping wet for more than 24+ hours after watering. Common symptoms of over-watered pear trees include yellow and dropping leaves and root rot (more about root rot later).
Here’s how to fix pear trees that are over-watered:
- Apply 2 inches of compost every 1-2 months. Interestingly, compost also fixes over-watering. This is because compost not only retains soil moisture but breaks up the larger clumps of soil, allowing proper drainage.
- Avoid mulching your pear tree until the soil is draining properly. In this case, mulching decreases evaporation and can make over-watering and poor drainage worse.
For potted pear trees that are over-watered, the best way to amend the soil is to repot them with fresh potting soil.
2. Extreme Weather
For best results, aim to grow pear trees in USDA hardiness zones 4-8. This is between -30ºF and 80ºF. While pear trees can tolerate temperatures slightly above and below these ranges, this guideline will help them grow best.
Also, keep in mind that pear trees are deciduous, so it’s normal for them to lose all of their leaves in the winter. If you have a late frost or extended winter season, your pear tree might not grow leaves until mid-spring or even early summer.
Let’s take a look at the climate that pear trees prefer.
Too Hot
When pear trees are exposed to temperatures of 80ºF and above, their leaves get too hot which stresses the plant and hinders the growth of leaves and fruit. In this case, the plant can’t send moisture from its roots to its leaves fast enough, which causes the leaves to dry, curl, brown, and drop.
As pear trees are temperate plants, they generally do best in cooler climates. However, some varieties such as Bosc do well in warmer areas.
Here are some ways to keep your pear tree cool:
- Provide 2 inches of compost for water retention
- Apply 4-12 inches of mulch for insulation
- Provide at least 2 hours of partial shade in the afternoon. You can use shade sails, structures, or other trees
Too Cold
Since pear trees are temperate, it’s difficult for them to get too cold. For example, most varieties can survive down to -30ºF. As pears are deciduous plants, it’s normal for them to lose their leaves in the fall and winter and regrow them in the spring.
Keep in mind that when temperatures drop below 45ºF, plants typically enter a dormant state and have little to no growth. These are also called “Chill Hours“, which help the plant maintain dormancy and reserve nutrients and energy for springtime.
Additionally, many pear varieties such as Bartlett require around 1500 chill hours. While it’s not necessary, pear trees prefer some chill hours for proper growth and fruiting.
Here’s how to keep your pear tree warm when temperatures dip below 32ºF:
- Provide 4-12 inches of mulch for insulation
- Wrap the canopy with a bedsheet to reduce windchill
- Wrap the trunk with cardboard or another insulating material
Not Enough Sunlight
Pear trees require at least 6 hours of direct sunlight a day. While some pear trees can grow with as little as 4 hours per day, you’ll often see reduced growth the fewer hours the plant receives.
Sunlight is critical for plant and fruit growth as it encourages photosynthesis, or how the plant gets its food and water.
If your pear tree’s leaves are curling or browning, it could be a sign it’s getting too hot and could use some shade from the afternoon sun. In this case, use the shade from other trees, structures, or items such as shade sails. 2+ hours of daily, partial shade from the western sun will work.
Here are some tips to boost the sunlight for your pear tree:
- Plant on the south side of your property for maximum sunlight (if you live in the southern hemisphere, this is the north side).
- Place the tree near a south-facing wall to allow heat and sunlight to reflect onto the tree (you’ll likely need to provide it with more water than usual)
- Prune any trees above the pear to allow for more sunlight. You can also prune the pear tree’s excess and overlapping branches to increase sunlight and airflow into the canopy (and reduce pest and disease exposure).
3. Improper Nutrients
Excess Nutrients
Excess nutrients (over-fertilizing) chemically burn the pear tree’s roots, causing stress and leading to poor growth as well as decreased flowering and fruiting. Normally, fast-release chemical fertilizers are the cause of over-fertilization as organic fertilizers and compost aren’t potent enough.
Lack of Nutrients
| Nutrient Deficiency | Leaf Symptom |
|---|---|
| Nitrogen | Entire leaf is pale or yellow |
| Iron | Dark green veins, rest of the leaf is yellowing |
| Zinc | Yellow blotches |
| Manganese | Broadly pale leaves, foliage color looks mottled or smeared |
A lack of nutrients also causes the tree stress, leading to similar conditions such as stunted growth and little to no flowers and fruit. This is commonly caused by poor soils, leaching, and other conditions such as improper pH.
Nutrient leaching occurs when the nutrients seep too far down into the soil, out of reach of the plant’s roots (beyond about 2-3 feet). This normally happens when soils have too much drainage or are over-watered. For example, sandy soils are notorious for their leaching properties.
Fortunately, most of these issues can be resolved by properly fertilizing pear trees.
The Best Way To Fertilize Pear Trees
The three main nutrients for pear trees (and most plants) are nitrogen, phosphorus, and potassium (NPK). While nitrogen is by far the most important (vital for root and canopy growth), phosphorus is essential for flowering and fruiting.
The two main ways to fertilize your pear tree are with fertilizer or compost. If you choose a store-bought fertilizer, aim for a balanced NPK (nitrogen, phosphorus, and potassium). For example, use a 10-10-10 NPK.
If you choose compost, select one with the highest quality and freshness if possible as its beneficial organisms will still be alive.
However, while chemical fertilizers have nutrients in quantity, they typically don’t have quality nutrients.
Even though chemical fertilizers might be sufficient over the short term, over the long term they often short-circuit the nutrient exchange between the tree and its beneficial soil life (such as mycorrhizal fungi). This leads to dry and dead soil (AKA dirt) and overall decreased plant health.
Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.
Department of Biology, University of Fribourg, Switzerland
On the other hand, compost provides more than sufficient nutrients, increases water retention, and promotes healthy soils. Many gardeners are even finding that compost is replacing their fertilizers.
Either one you choose—you can see my recommendations for both compost and fertilizer on my recommend fertilizer page.
Soil pH
Pear trees do best with a soil pH of 6.0 to 6.5 (source).
While nutrients are important, they’re next to useless if the soil does not have a proper pH. This is because a slightly acidic pH is necessary to dissolve the nutrient solids in the soil and make them accessible for the plant’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.
Donald Bickelhaupt, Instructional Support Specialist, Department of Forest and Natural Resources Management
Two good ways to check your soil’s pH are either by using a pH strip or a pH meter. I prefer using a pH meter since they’re affordable and easy to use. To see which pH meter I use and recommend, check out my recommended tools page.
If you find that your pear tree’s soil is too alkaline (above 6.5) you can add acidic amendments such as coffee grounds, sand, and peat moss. On the other hand, if your pear tree’s soil is too acidic (below 6.0), add alkaline materials such as wood ash, charcoal, or lime.
Additionally, cold and/or wet soils are not good at promoting nutrient uptake as the pear tree will either be dormant during the cold or too stressed in wet soils.
4. Transplant Shock
If your pear tree was recently planted or repotted, and its leaf growth has slowed or stunted, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.
In this case, the pear tree is stopping its canopy growth to instead regrow its roots.
Avoid transplanting pear trees unless necessary as it can take up to 1 year for recovery.
To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the plant’s stem and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the plant in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the plant as before
- Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
- Water generously and add more soil as needed
5. Pests
Aphids
Aphids are small bugs that suck the sap from underneath the pear tree’s leaves. This loss of sugar and moisture causes the leaves to curl, discolor, and drop. Aphids also deposit honeydew, which attracts ants.
If left unchecked, aphids can damage the pear tree’s health and potentially stunt or kill it.
These bugs come in multiple colors including white, yellow, or black, and usually are found hiding underneath the leaves. Typically, aphids won’t cause damage to the fruit, but because they suck sap from the plant, they can compromise its health and therefore reduce fruit size and yield.
The best ways to get rid of aphids (and mites) on pear trees is by spraying the infected leaves with water or neem oil, or releasing ladybugs (a natural predator of aphids and mites). Most often, a jet of water is enough to knock them off and kill them, but neem oil is a good second option.
For example, when my potted Kaffir lime tree had aphids, I found that a jet of water was sufficient to blast them off and prevent them from coming back. All I did was remove the hose nozzle and used my thumb to increase the pressure. Just keep in mind that too strong of a blast can damage the leaves.
Spider Mites
Spider mites are similar to aphids, except they’re part of the spider family. They also feed on pear trees and cause stunted growth as well as leaves turning yellow, red, and dropping.
The main differences in appearance between aphids and spider mites are the spider mite’s ability to spin webs. These webs can cause damage to other parts of pear trees such as the twigs and fruit.
So, if you see small dots on your pear trees, see if they’re depositing honeydew or webs and you’ll likely identify if they’re aphids or spider mites.
6. Diseases
Root Rot
Root rot kills off the pear tree roots, which stresses the plant and causes symptoms such as fruit, flowers, and leaves yellowing, browning, and dropping. If not addressed, it leads to stunted growth or a dying pear tree.
You can typically tell if your pear tree has root rot if the soil is staying sopping wet and starts smelling. Allowing the soil to dry out or repotting pear trees with fresh potting soil are the best ways to amend this disease.
For example, I noticed my potted Kaffir lime tree had root rot as its soil smelled swampy and was staying wet for many days at a time. In this case, I repotted it with fresh potting soil, and the tree quickly recovered.
Verticillium Wilt
Verticillium wilt is a fungus that is similar to root rot in that it usually occurs in soils with excess water. Additionally, over-fertilizing can also cause it.
The most susceptible fruit crops that contract verticillium wilt are nightshade (tomatoes, peppers, and eggplants), but other fruiting plants such as pear trees can also be infected. Symptoms of this disease include leaves wilting, yellowing, and dropping, and potentially branch dieback.
Prevent and treat verticillium wilt by pruning infected branches, avoiding excess water and fertilizers, and following best gardening practices.
