Watering plants growing in containers is a key task to take care of in summer. This guide to watering your container garden will cover watering tips for outdoor potted plants such as veggies, fruit, herbs and flowers.
So how do you ensure that containers get enough water during the hot, dry summer months? By picking the right containers, the right soil, checking daily if you need to water and watering consistently, even when you’re busy or away on vacation.
Why plants in containers need to be watered
Growing veggies in containers or planters is a great way for many food growers who might not have the space or ability to have large raised or in-ground veggie garden beds.
However these container plants need consistent watering, because with less soil that a garden bed, they will dry out quickly in hot, dry summer weather.
This is especially true for hanging baskets which are more exposed to drying wind.
Plants that don’t get enough water will be stressed, meaning they won’t grow much, set fruit and will be more susceptible to disease and pest damage.
Picking the right containers for dry, hot summer weather
One key step to keeping your planters or containers well hydrated in summer is to pick the right containers in the first place.
Unglazed terracotta can dry out quickly as it’s porous, so it may not be the best choice if you have consistent hot, dry summers. Especially smaller terracotta pots will dry out in a matter of hours in the hot sun, which means you’d need to water multiple times a day.
Metal containers can also not only dry out quickly but can get so hot they can damage plant roots and bake the soil.
The best materials for growing veggies in containers are plastic, resin and wood. These have some insulating capabilities to keep the hot sun from baking the soil and your plants.
Another tip when shopping for new containers: consider getting self-watering containers that have a special water reservoir that helps keep soil moist even in very dry conditions. They are more expensive but will save you time and effort and your plants!
If you don’t want to spend the money on self-watering containers, placing a deep drip tray underneath your containers will help. When you water you can let the drip trays fill up with the overflow. Just be careful during wet, cooler weather that the drip trays don’t stay full for days as then your plants’ roots could rot.
Picking the right soil for containers that won’t dry out as quickly
The other preparation step you should take is to pick the right soil for your planters or containers.
Regular garden soil will dry up and be hard as a brick, especially if it contains clay. That won’t give your plants’ roots much chance to develop.
The best soil to fill containers is a good quality organic potting soil. Most contain ingredients that retain moisture and keep the soil fluffy and well aerated.
The most popular material for this is peat moss, although coconut coir is being used increasingly more, because of its better environmental footprint.
This is a good potting soil mix for containers that helps to retain moisture:
Other moisture-holding materials are perlite and vermiculite. There are also some soils that contain a polymer that holds onto water and slowly releases it, but it’s not a natural material and usually is not safe to be used for any edible plants.
Adding a good quality sterilized compost can also help with water retention. And it will help feed your plants as well.
Once you’ve planted everything, topping off the soil surface with a moisture holding mulch will also help. Mulches you can use in containers include compost, leaf mulch, fine wood chips and straw.
How to tell if you need to water your container veggie garden
So what are the signs that you’re under watering your plants in containers?
You’ve probably had the experience of checking up on your plants after a hot day and seen the signs that your plants need water. Usually that is wilting of the plant foliage.
However wilting during heat of day is normal but not in the cooler morning or evening. Wilting is a way for plants to conserve moisture during the hottest part of the day so may not be a good indication of lack of water.
There are better ways to tell when a plant needs water.
The best way to know when to water plants is with the finger test. Insert your finger into the container about an inch (2.5 cm) and see if the soil is moist. If it’s dry, time to water.
You can also purchase moisture meters that you just stick in the soil and a dial will show you the moisture level. This is a simple one from Amazon that will do the trick:
The other indication is if the planter is light in weight. This only of course works for small to medium-sized containers. Try lifting the container and if it feels light compared to when it’s well-watered it’s time to water the container.
Your plants will also tell you if they need water. If you start seeing leaves turning brown and crispy, this could be a result of under-watering. If you have partially developed fruit falling off (such as tomatoes or peppers) that can indicate the plant is trying to conserve moisture and shedding excess fruit to survive. Most plants will also simply stop growing.
Severely underwater containers will also have the soil in the container pull away from the sides, leaving a gap. In those cases, you’ll need to water a little bit at a time to slowly saturate the soil otherwise water will just go past the soil on the sides. It helps to also take a trowel or your fingers and push the soil back so it touches the sides again.
How to tell if your plants have been overwatered
On the other end of the spectrum is overwatering. That’s harder to do with containers with drain holes as they do drain any excess water. But if you’re using self-watering containers or drip trays or containers without holes, your plants could get waterlogged.
Signs that your plants have too much water include yellow or brown limp leaves (not dry). If the base of the plant starts looking mushy or the soil smells a bit rotten, that’s also a sign that you’ve overwatered your container plants.
Mold, algae or mushrooms growing on the surface of the soil also indicates over-watering but it could also be a lack of airflow around your containers. It’s always a good idea to keep containers a little bit apart for better air circulation around them.
How often should you water your outdoor container vegetable garden
The weather has the greatest effect on when you should water container plants.
Containers can dry out quickly in the hot sun, even if the outdoor temperature may not be that hot.
Hanging baskets are prone to drying out from wind as well even if it might not be that sunny or hot.
So ideally you want to water your container veggie garden at least once a day during dry, hot weather, possibly even twice a day if needed. Water until some water comes out of the drain holes. Always make sure that you don’t have anything underneath your containers that can’t get wet or use large drain trays to guard against that.
Newly sprouted or transplanted young plants need lots of water to establish themselves as they don’t have the extensive root structure to find water at the bottom of your containers. So you may need to water them more than twice a day. It can also help to put them in a shady location, as long as they get enough sunlight.
It’s best if you can avoid the hottest part of the day when watering. Try to water your containers first thing in the morning before heading off to work and then check on them again in the afternoon when you return home to see if they need more.
In cool, damp weather you may not have to water at all. But keep in mind any containers under an overhang or under dense trees might not get much rain.
But keep in mind your individual plants’ watering needs. Veggie plants that produce green leaves, need more water to keep those leaves well hydrated. Whereas plants that grow roots typically need less and too much water could actually rot the roots. Fruit usually requires more water, especially stone fruit, citrus and berries as they are made up of over 80% water.
How to keep your container garden watered using automated watering if you don’t have much time (or might forget!)
Busy families might find it difficult to find time to water their container garden every day. Or they might forget.
So they’re looking for a way to water potted plants automatically.
There are lots of automatic watering system for potted plants. You can buy a complete drip irrigation watering kit for containers and hanging baskets that includes drip irrigation emitters for pots. You just connect it to an existing outdoor water faucet.
There are even kits designed to connect to a rainwater collection barrel.
This is a popular kit on Amazon that’s quite versatile for different container garden layouts and can be added to over time.
Other ways you can automatically water your plants include using water bottles upside down with small holes poked in the lid, using strips of cloth wicks in a large water bottle that go to multiple containers and using drip trays as bottom watering reservoirs. I cover these three options in the following video:
And of course the aforementioned self-watering containers. Here are the links again to some popular ones on Amazon:
How do you keep potted plants watered while on vacation?
If you’re going on vacation, ideally you’d want someone to water your plants. But that’s not always possible.
So some tips on how to keep your container plants from drying out when you’re away:
- Move what containers you can into a shadier area, out of the hot sun. Even better if you can move them to a spot where they will get water from an automatic watering system. Key is to keep them cool. Or erect some kind of shade such as an outdoor patio umbrella, shade cloth or even an old bedsheet, securely fastened against wind. This should normally be okay for most plants if the time you’re away is short (a week or less). Remember to move them to their original location or remove the shade materials when you are back and can resume regular watering.
- This may contradict the above tip, but if rain is expected while you’re away, move the containers from underneath any overhangs from your house, a porch, etc. so that the containers will get the benefit of the rain
- Employ some self-watering hacks such as the ones in this video [link to video]
- Use drip-irrigation on a timer. You can find links to these in my Watering Essentials kit [kit.co link]
- Use a thick mulch on top of the soil such as wood chips, straw, compost or leaf mulch – make sure to water the containers well so both the mulch and soil underneath is well saturated
- Avoid using terracotta as this can dry out more quickly. Plastic, resin or wooden containers are best and the larger the containers, the slower they’ll dry out
I have more tips in this article including how to arrange for someone to take care of your plants while you are away on vacation:
So with these container garden watering tips you should be able to keep your outdoor planters watered the whole summer!
And remember to hydrate yourself as well and stay cool!
If you enjoyed this article, have something to add or have any questions, please leave a comment below.
Wishing you all the best!
Tranquil Urban Homestead, Victoria, BC