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How much water do flowers really need? Even experienced gardeners can benefit from a refresher on how to water flowering plants, whether in the ground or in flower containers.
Watering flower containers is quite different than watering in-ground beds, so let’s start with the flower pots.
Watering Flower Pots
Flowers and vegetables growing in pots have only a limited amount of soil to draw moisture from and their roots can’t expand outward to search for more in dry weather. These are going to be your neediest plantings—especially those in sunny locations—so be sure to check them daily or even twice a day if the weather is hot and dry. Remember that wind also tends to dry out your plants more quickly, causing them to wilt.
When to Water Flower Containers
When it comes to containers, it’s better to look for cues on whether the plant needs water versus watering on a set schedule.
Look at the soil color. Dry soil is lighter in color. Wet soil is darker in color.
Check the pots to make sure the soil has not pulled away from the edge. Water will just run down that space and right out of the pot instead of sinking in around the roots where it is needed. Add more soil to fill that gap if necessary.
Put your finger in the soil, down to the first or second knuckle. Water only when this top layer (1-2 inches) of soil is dry.
If the soil is too dry to hold water, put a tray under the pot to catch run-off water; it will be reabsorbed through the drainage holes.
Do not water at night (unless the plant is desperate for water) as this invites disease. Also, be sure to water the soil—NOT the leaves!
Again, don’t set a schedule. When plants are small in the spring, they may need less water than they do when plants get bigger and the weather gets hotter. Adjust accordingly!
How Much to Water Flower Pots
When you water, it’s important to keep watering until the water comes out of the pot’s drainage holes.
Of course, your pot must have draining holes or the roots will get overwatered (waterlogged). At least one drainage hole is usually fine.
That said, do not let your container sit in water. Make sure the water drains out.
It can take a surprising amount of water to thoroughly water a pot! A 10 to 12 inch pot may need up to a gallon of water. However, it’s very important that you are fully watering the root ball of the plant so that it can keep putting out roots and thrive.
If you water fully, you will also find you may not need to water quite as often. Of course, this completely depends on your weather and the size and type of container.
The hay rack container with coir liner (bottom) is going to dry out faster the the plastic planter on the top railing.
Flower Pot Dehydration
If your plant and soil has become dehydrated (wilted plant, dried-out soil), you may find the water just runs over the sides of the container. To re-hydrate, there are two methods:
Immerse the entire pot in a tub or bigger container of water. This works for smaller pots
Water fully (as described above). Wait 30 minutes. Keep watering every 30 minutes until the water starts to get absorbed by the soil. This extra TLC may take several rounds.
Watering In-Ground Flower Beds
Since flowers (and vegetables) planted in the ground have a larger area for their roots to run, they are a little more self-sufficient than those confined to containers.
How Much to Water Flowers in the Ground
The rule of thumb is 1 inch of water a week during the growing season, but we all know that some thirsty plants require more than that, while deeply-rooted perennials and xeric plants are just fine with less.
What is 1 inch of water? This means a one-inch deep layer of water over the entire soil surface that needs watering. The formula is essentially 1 inch of water per 1 square foot = 0.62 gallon. If you wish to get a sense of how much water that is, place 4 or 5 tuna cans (straight-sided) around the garden during a rainfall. When 1 inch of water from rain has collected in the containers, that indicates that 1 inch of water was applied to the soil.
The easiest way to measure soil wetness is to buy a soil moisture meter; you can find them online for less than $10.
But nothing beats the finger test. Stick your finger into the soil about 2 inches down and if it’s dry, it’s time to drag out the hose.
Paving around this flower bed adds even more heat during the hottest part of the day so these plants will require more water than those in other beds.
How Much Water Do Flower Beds Need?
Don’t be too alarmed if your plants wilt during the hottest part of the day. Wilting is a natural survival mechanism for many broad-leafed annuals. Once the sun gets lower, they should perk up again.
Watering After Planting
When planting flowering plants, make sure the rootball is wet and the ground is moist. Plant after a rain if possible.
Give the plants a good drink to settle the soil around their roots to lessen the shock of being transplanted. Plants that have a good start will perform better than ones that have to struggle early on.
How to Conserve Water (and Water Less Often)
In many parts of the country, water is at a premium and using it for gardens and landscaping is at least limited if not totally banned. What’s a gardener to do?
To encourage your plants to develop deep roots, when plants need watering thoroughly soak the ground once rather than applying many shallow waterings.
To reach the roots, the water has to go about 6 inches down into the soil. To test how far your water went, dig down after watering. You’ll be surprised! In a dry season, it can still be powdery.
Again, be sure to water the soil and not the leaves. A gentle flow at the base of the plant will do more good than an overhead sprinkler that wets everything in its path. Soil splashing up onto the leaves can also spread disease. Sprinklers also waste a lot of water, losing it to evaporation. Drip irrigation or soaker hoses will deliver the water right where it is needed and can be set with timers to turn on and off, making your job easier.
Try to water in the early morning or late afternoon rather than during the heat of the day when a lot of the moisture will quickly evaporate.
There are plenty of plants that don’t require huge amounts of water to thrive. Look for succulents or ones labelled as drought resistant. Avoid plants that are water hogs (e.g., Elephant Ears, Hydrangea). See best flowers for containers.
Look at your soil. Different soil types hold water better than others. If yours is too sandy, mix in compost, shredded leaves, coconut coir, well-rotted sawdust, or aged manure to increase its ability to absorb moisture.
Mulch, mulch, mulch. After planting, adding a layer of straw, shredded leaves, bark mulch, or pine needles will keep soil moisture from evaporating quickly.
Be mindful of micro-climates. Some areas of your yard will be hotter and drier than others, while there may be spots where the ground stays moist longer. Try to take advantage of these natural conditions.