How often should I water my tomato plants in pots?
One question that usually bugs the mind of tomato gardeners, especially the newbie gardeners, is how often they need to water their tomato plants. Whether the tomatoes are cultivated on garden beds, pots, or containers, the need to know the right time to water and how often to do it would always be something to think about.
The focus of the post, though, is about the water requirements of tomatoes planted in pots. This can be a unique challenge because potted tomatoes are more prone to drying compared to garden bed tomatoes. The main reason is down to the fact that the tomatoes grown in pots have roots that burrow deeply into the pot looking for moisture or water.
As well as looking at how often you have to water your potted tomato plants, the article would also discuss the factors that determine the watering frequency, the best time to water the tomatoes, how to determine if the plants need water, and several handy tips you’d find useful in your water management routine.
Table of Contents
How Often Should I Water My Tomato Plants in Pots?
You should know right off the bat there are no hard and fast rules when it comes to the optimal watering frequency of potted tomatoes. How often you water your plants depends on several factors we would look at later.
It is critical to keep in mind that soil in pots loses water faster compared to garden beds. This is basically because of the all-important drainage holes under the pots and the fact that relatively little water is required for each watering session.
The most important thing when it comes to the frequency of watering potted tomatoes is to ensure that the soil is constantly moist. While soil moisture is a desirable target, you’d also have to be careful not to over-water the tomatoes.
In the first place, watering too much is a waste of water since the excess water drains out through the holes. And secondly, too much water can leach the potting soil of important nutrients via the water draining out.
Generally, the recommended frequency for watering tomatoes grown in pots is twice daily during a heatwave or when the weather is hot and humid. The first time should be at the break of dawn and again later in the evening.
But this could be more, or even less. Again, whether you need to water more often or less depends on factors we would discuss in a bit. But the major determinant of how often to water the plants is the state of the soil in terms of moisture levels.
How to Check Soil Moisture of Potted Tomatoes
Knowing how much water the soil needs and how often to water the tomato plants often boils down to how moist the soil is. Research shows that tomatoes grown in pots or containers don’t do well if the soil is dry even if other growing conditions are optimal.
The ‘Finger test’ is the easiest way to check if soil moisture is enough to support plant growth. The test requires sticking the finger into the soil to a depth of about 2 – 3 inches. If the soil feels dry at about 1″, it is pretty safe to assume the tomatoes need water.
Another way to test for soil moisture is to get a soil hygrometer known as soil moisture meter. There are different types for sale made by a host of manufacturers with varying levels of complexity.
No matter the design of the soil hygrometer, the basic operation involves gently inserting the probe section of the device into the soil up to about four-fifths of its length. The dial or meter would indicate the soil moisture level after about 1 minute. This is a more accurate means of determining whether your potting mix is dry and needs watering or not.
The vital takeaway from all this is that the tomatoes might not necessarily need water if the surface of the soil looks dry. Sometimes, the surface might be dry but very moist at less than an inch below the surface.
How often is the soil test necessary? The rule of thumb is to err on the side of caution and do it every day especially during long spells of dry, hot, windy, and humid weather.
Factors Affecting How Often to Water Tomato Plants in Pots
The pot
The type of pot used can affect how fast the soil loses moisture and invariably the water needs of the tomatoes. For instance, clay pots are known to wick moisture out of the soil causing it to dry a lot faster compared to plastic and other types of pots.
The color of the pot also affects how fast the soil loses moisture. Black or dark-coloured pots would lose water faster than light-coloured pots. Because dark pots get hotter faster, this raises the soil’s temperature leading to lost water through evaporation when compared to light-coloured pots.
Weather
How the prevailing weather conditions affect how often tomatoes grown in pots are watered is pretty straightforward.
The hotter the weather the higher the water demands of the soil. During spells of high daily temperatures, you’d have to check the soil moisture at least twice a day to ensure it is not dry.
When the weather is mild though, early spring and late fall, for instance, checking the soil can be done once a day. And because temperatures are low, you won’t have to water the plants as often. Watering once every other day would be adequate in most instances.
That said, you want to mitigate the negative effects of high temperatures (midday sun) on the plants by moving them to a shaded area. If left in the sun, apart from accelerating soil moisture loss, the tomatoes can suffer from sunscald, discolouration, wilting, and some fungal diseases.
Potting soil quality
If the soil is very porous, water drains out easily while the increased airflow in the soil means the soil will dry out faster. The tomatoes would require frequent watering in this case compared to the heavier soils that retain water better and therefore remain moist longer.
The best potting soil for growing tomatoes in pots should contain adequate organic materials such as compost and peat moss. This helps water retention while ensuring that the soil isn’t waterlogged.
Location of pots
Where you put your tomato pots is also very critical. If the pots get the full blast of the sun, that would lead to faster drying of the soil and water loss via evaporation and leaves.
Also, you’d want to be careful how windy the location is if you don’t want to water your plants too frequently because winds promote faster soil drying.
Pro Tips on How often to Water Tomatoes in Pots
– Reducing the frequency and quantity of water when the fruits are almost ripe would improve fruit flavour
– Practice mulching to help retain soil moisture
– If your tomatoes show persistent wilting even with regular and adequate watering, the problem may lie elsewhere.
– Drooping tomato plants around mid-day isn’t always a sign of inadequate water. This is sometimes a defensive mechanism by the plant to reduce the loss of water. But if the condition persists after sunset, it’s most likely the soil is parched and needs water.
– To prevent your potting soil from draining out with the water, line the bottom of the pot with linen or polypropylene weed block fabric or coffee filters over drainage holes.
