How often to water blueberry plants is partly a matter of the plants’ ages, of your climate, and of your soil type. Figuring out this equation may mean the difference between a large blueberry year and a medium blueberry year. You probably want to get it right, because a large blueberry year is the whole point of growing these summer treats! In this article I’ll explain how the plants’ root systems work, the frequency and the quantity of watering needed, and how to tell if your blueberries are getting enough water.

To help you understand how often to water blueberry plants, you’ll also read about how to reduce the watering required by your blueberry plants, which is important for any water-wise garden. All of the information provided here is relevant for blueberries growing in pots as well as those growing in the ground or in raised beds.

The blueberry root system

While many perennial shrubs have deep roots, blueberry plants have a shallow but broad, fibrous root system. The plant’s fine root hairs are responsible for transporting water and nutrients from the soil to the plant. Reaching just 1 to 1.5 feet deep, blueberry plant roots are susceptible to injury from drying out in drought as well as to root rot in wet soils.

Because the roots spread up to 1.5 feet wide around the plant, be careful to apply water, soil amendments, and fertilizers across the whole root area. Use the plant’s drip line (the outermost spread of its leaf canopy) as a good measure for distribution. This is especially true for amendments and fertilizers that adjust the soil pH, as blueberry plants need more acidic soil than most plants, and for nitrogen fertilizers, which are more likely to burn plant roots. When amending for pH, avoid aluminum sulfate altogether, as this is toxic to blueberries. Fertilizers like HollyTone or ammonium sulfate are better choices to maintain acidic soil conditions.

Understanding blueberry plants water needs

The blueberry fruit itself is mostly water. It stands to reason the blueberry plant needs to receive enough moisture to supply its basic functions, to create good yields of plump berries, and to develop shoots and buds for next year’s harvest. Unbelievably, in hot, humid, breezy areas, a mature blueberry bush could use as much as 2 to 3 gallons of water per day through its leaves!

Factors affecting watering frequency

There are a few variables in understanding how often to water blueberry plants. Before you pull out your hose, consider:

• Newly planted blueberries need frequent water to establish strong root systems.
• Blueberries planted in sandy soil types need more frequent watering than those planted in heavier, clay soils.
• Bright and sunny days will zap moisture from the soil, so be ready to water more often come July and August.
• Plants in containers need more frequent watering than those in the ground and in raised beds (see later section specific to container blueberries).
• Berry plants in growth and production stages have higher water requirements than those that are dormant.

Adjusting for different stages of maturity

How often to water blueberry plants, and how much to water them, changes as the plants mature. Newly planted blueberries require more frequent, deeper watering as the roots become established. After the first year, variability in watering becomes more about growth and dormancy stages. From early spring through fall, they’re busy creating new growth and fruits, which usually requires supplemental irrigation. Come winter, the roots’ water needs decrease, as their job now is to keep the plants alive but not push new growth.

Establishing how often to water blueberry plants

Plan to water blueberry plants once or twice a week throughout the growing season, if regular rainfall does not occur. Container blueberry bushes will require daily watering in the summer (see section below). You want the root zone to be moist, but you don’t want standing water or mud. Whether you’re irrigating the plants or letting nature water them is dependent on the weather, of course. The next section covers how much water to apply.

Get to know your soil type and how water moves through it. You may even dig into the soil to see how wet or dry it looks about 1 foot down to determine your ideal watering schedule. Give it the finger test: Dig your finger into the soil to gauge moisture. If you want to be especially precise, purchase a moisture meter so you don’t have to guess at how often to water blueberry plants.

How much water to add when watering a blueberry bush

In addition to understanding how often to water blueberry plants, you need to determine how much water to give them. Thirstier than most garden plants, new blueberry plantings and those in production need 2 inches of water per week spread across their full root zone, whether that’s by rainwater or tap water. Once established, and outside of the peak production season, blueberry plants should receive 1 to 1.5 inches per week.

So how do you know you’ve applied 1 or 2 inches of water? Well, since 1 inch of water equates to .62 gallons per square foot, you can derive that for a mature 3’ x 3’ blueberry bush root zone (9 square feet), 1 inch of water equates to 5.5 gallons. 2 inches of water equates to 11 gallons. This amount should be applied slowly all at once, or divided into twice-a-week waterings.

These are only guidelines. Use your soil and your plants as the real indicator of how much water is needed.

Signs of under- or over-watering

You’ll receive clues that it’s time to adjust how much or how often to water blueberry plants by observing their growth and changes in your garden. When a blueberry plant has the proper nutrients and the ideal soil pH with adequate soil moisture, it shows off its deep-green leaves.

If you’re under-watering your blueberries, you’ll see:

• The tips of new shoots wilting on hot days. If this continues to happen, the plant will stop producing new growth.
• Reduced berry size, and shriveled berries in extreme dry conditions.
• Brown and brittle leaf edges that may lead to leaf die off.

Over-watered blueberry bushes’ primary danger is root rot, caused by the Phytophthora cinnamomi organism. Too much water takes longer to notice than too little water, because the signs typically don’t show above ground until root loss has occurred.
At that time, root rot looks like:

• Leaf yellowing or reddening
• Browning along the edges of leaves
• Stunted growth
• Bud die off

How often to water blueberry plants growing in pots

Blueberry bushes growing in pots likely require more frequent watering than those growing in the ground and in raised beds. The smaller the container, the faster its soil dries out. In hot and dry weather, you should be watering every day. Check the soil moisture level to be sure it remains consistent—not sopping wet, but not dried out—and adjust your watering schedule to accommodate that. When growing blueberry plants in pots, be sure your container has drainage holes to allow excess water to move through the soil and drain away.

Tips to reduce watering needs

It’s possible to both grow blueberries and be a water-wise gardener, even given these plants’ thirsty nature. Here are a few tips:

1. Use drip irrigation or soaker hoses. These deliver water directly to the soil and can even be controlled by a weather-sensitive timer. This form of watering also keeps the leaves dry, reducing the chance of disease.
2. Mulch the plants with an organic mulch, such as straw, pine straw, shredded bark, or even sawdust from non-treated lumber. This fundamental water-conservation gardening tip cannot be repeated enough. An organic mulch cools the soil and reduces water evaporation.
3. Weed the blueberry patch. Hand weeding is best around blueberries, as their shallow root systems can be damaged by mechanical weeding. Removing the weeds means you’re removing plants competing against your blueberries for water.
4. Properly prune blueberry bushes to remove older canes. Regardless of whether you’re growing Northern highbush, Southern highbush, rabbit eye, or hybrid blueberries, annual pruning is essential. In late winter, before flower buds form, trim off old wood so the plant can focus its resources on its new growth and berry production. (Learn all about blueberry pruning in this article.)
5. Amend the soil with compost to build up organic matter. This improves the water retention and filtering capacity of the soil, helping to keep the balance of just the right amount of soil moisture.

Thirsty no more

Determining how often to water blueberry plants is an important part of growing blueberries at home. I wish there were a simple answer to the equation of how much to water and when! My best advice is to know your soil type and whether water drains through it quickly or slowly. Get to know the plants’ stages of growth and production. Also, pay attention to your weather. All of these factors will help you determine how often to water blueberry plants.

By understanding blueberry bushes’ root systems and applying water-wise gardening techniques to your blueberry planting, you’ll find you’re spending less time irrigating and more time enjoying your harvest of plump, juicy fruits.

For more information about growing great berries, check out these additional articles:

• Pruning blueberries
• Fertilizing blueberries
• Growing golden raspberries
• Pruning raspberries
• Transplanting raspberries