How Much and How Often Should You Water Petunias?

Not sure how much water your petunias need, or how often you should be watering them? In this article, gardening expert Paige Foley examines how much moisture your petunias will need, from when they are first planted, to when they are in full bloom.

Written by Paige Foley Last updated: October 2, 2023 | 4 min read

A hand gently holds a green watering can, poised to nourish a vibrant array of potted petunias in different hues. The petunias bloom in shades of red, purple, and white, creating a delightful mixture of colors. The rectangular pot contains rich, dark soil, complemented by neatly trimmed grass beneath.

Contents

You’ve decided to grow petunias but are unsure how much water they need and how often. Don’t worry! Irrigation doesn’t have to be daunting and can become a habit if done regularly. They are a favorite among many gardeners for their laid-back, easygoing habits.

Petunias are one of the most commonly grown flowers in the garden. This is because they provide continuous blooms all season and are fairly low-maintenance. They thrive in full sun to partial shade, depending on your region.

Understanding how much and how often to irrigate your petunias will set them up for success in hanging baskets, pots, flower beds, or your landscape. Let’s dig into how to water your petunias properly and how often.

The Short Answer

Petunias are rather drought-tolerant. They can handle dryer conditions but may be less productive during periods of little to no water. Still, this doesn’t mean you should go weeks without irrigating your petunias. If you want your petunias to have numerous vibrant blooms, water them once or twice a week. If your region is experiencing hot and dry conditions, water more frequently.

Potted and hanging petunias may require more frequent watering than petunias planted directly in the ground. Checking the soils where you have planted petunias will be the best indication of whether or not you need to water. The soil should be moist but never soggy.

The Long Answer

Petunias are not finicky plants. Nonetheless, here are more details about perfecting their irrigation schedule for maximum blooms.

Watering Petunias

A green watering can gracefully tips, allowing water to cascade onto a potted petunia. The plant boasts two striking blooms—one radiant red and the other pure white—as well as lush green leaves. Its white pot cradles the petunia, situated on a bed of dark, nutrient-rich soil. — Watering in the morning is ideal as it allows foliage to dry out during the day.

Petunias will give their best show if watered regularly and consistently. We want the plants to establish deep roots rather than shallow ones. Deep roots allow them to access water deep below the soil’s surface, creating more drought tolerance.

Shallow roots can’t access the moisture that’s deeper in the soil. When drought conditions set in, shallow-rooted plants suffer and dry out quicker. This is why it is best to soak the area well instead of watering lightly.

These flowers prefer low humidity, which makes morning an ideal time to water in most climates. Irrigating in the mornings will allow moisture on the leaves or plant to dry during the day. If watered during the evening, moisture sits on the plant and can cause disease to grow.

How Often to Water

The frequency of irrigation depends on the type of container and soil.

Pots

From a yellow-green watering can, water gently flows onto a potted petunia, nurturing the plant's numerous yellow blooms. The petunia's delicate green leaves provide a lovely contrast to the vibrant blossoms, creating a captivating sight. — Check your potted petunias every few days to assess soil moisture.

Petunias are an excellent container plant. They provide beautiful blooms and lush green foliage all summer long. You can have them cascading all around or as a mounding filler with companion plants. But how often should you irrigate flowers in a pot or container?

Pots and containers need consistent and regular watering. Give your pots a good soaking at least once per week. Petunias are somewhat drought resistant but need deep roots to survive dry periods. Choose a pot that’s deep enough to allow the roots to expand.

If you choose a shallow pot, the roots can’t grow as deep and may require more frequent irrigation. You can grow them in a smaller pot, but they must be monitored to ensure proper moisture levels.

Check your pot’s soil every few days to determine if it needs moisture. Feel the soil, and if the soil feels wet an inch or so below the surface, delay watering for a day or so. If soils are dry and crumbling and you must dig down to find moisture, give your petunias a shot of water.

Hanging Baskets

Tenderly held by a hand, a yellow-green watering can showers a petunia plant with life-giving water. The plant showcases beautiful purple blooms, some with paler petals and a darker center. Its slender green stems are adorned with small, vibrant green leaves, enhancing the plant's overall charm. — A simple method of lifting your hanging baskets can determine if they need watering.

Petunias growing in hanging baskets stand out and shine. However, hanging baskets have more water demand than most other locations. While they have excellent drainage and airflow, they also dry out quicker.

Generally, hanging baskets should be irrigated weekly with a thorough soaking. If you want beautiful, luscious petunias, consider watering 2 to 3 times a week. Once you see water running out the bottom of your hanging basket, it indicates they are thoroughly watered.

Lifting the basket is the easiest way to check and see if your hanging baskets need to be watered. If the basket is easy to lift and light, water immediately. If the basket is hard to lift and heavy, check again in a day or so to see if they need a drink.

Many commercial potting soils contain a high volume of peat moss. If peat moss is allowed to dry completely, it becomes hydrophobic or water-repellant, and it’s difficult to rehydrate the peat moss to get consistent moisture again. If your basket feels light, but the soil is still damp to the touch, it’s the perfect time to water to prevent the water from running straight through the potting blend and out of the bottom of the pot.

Garden and Landscape Soil

A blue watering can pours refreshing water onto a vibrant petunia plant. The petunia flaunts a captivating red bloom amidst its lush green leaves, thriving in the brown soil below. Nearby, a few other plants stand at a small distance, with one particular plant boasting white blooms and residing in a plastic pot. — Incorporate mulch or rocks into your flower bed or landscaping to help retain moisture in your soils.

How often you should irrigate any plant depends on the soil drainage, climate, and airflow. Petunias prefer well-draining soils that have good organic matter and nutrients.

If you have heavy clay soil, water will have difficulty draining. This is less than ideal for these flowers. In contrast, sandy soils tend to drain too quickly and tend to dry out fast. If you have either of these soil types, consider adding compost.

Compost will hold moisture and nutrients that tend to leach from certain soil types, and it also breaks up clay-like soil. If you know you have poor-draining soils, amend them before planting. It may be difficult or impossible to amend soils once planted.

Add mulch or rocks to your flower bed or landscaping if you struggle to retain soil moisture. These are great options that protect the soil from sun and wind exposure. A good layer of mulch or rocks will seal in moisture longer and could reduce the number of waterings you must make. If you live in a hot and dry climate, mulch is more effective than rocks as it’s typically made of organic matter and can hold a little water, too!

Check your soils periodically to assess soil moisture. Generally, petunias planted in a garden or landscape need less watering than those in pots or hanging baskets. Establishing a schedule will prove beneficial.

How Much To Water

Adorned in floral green gloves, a hand gracefully holds a silver grey watering can, while delicately touching the leaves of a potted petunia plant. The petunia presents pale purple and pale red blooms, which beautifully contrast with its small green leaves. The white pot rests atop meticulously trimmed green grass, completing the harmonious composition. — Generously soak your petunias once a week to promote deep root growth.

It is difficult to give an exact answer to this question. The amount of water a plant needs is highly dependent on its environment and on its climate. Your region is going to impact your watering schedule.

Regions that are hot and humid may need to water more than regions that are cool and dry. It’s important to monitor your petunias no matter where you live. I understand it may be difficult to check your petunias every day or every other day. However, it will pay off in the long run when you have big, gorgeous flowers that never stop blooming.

If possible, provide a generous soaking at least once a week. Of course, this will vary depending on whether they are in hanging containers, pots, or in the garden. Help the roots grow deeper by letting the area soak thoroughly.

Check the soil to ensure your plants are getting enough water. The soil should always be moist but never soggy. Petunias can develop problems if allowed to sit in soggy soils.

Final Thoughts

Watering petunias is pretty straightforward. As long as soils are moist, they will bloom nonstop from spring to fall. If you encourage deep root growth, they are somewhat drought-tolerant. Stick to a schedule; you’ll be impressed by how well they bloom and grow. Happy gardening!