How to Keep Container Plants From Drying Out Too Fast

If it seems like your potted plants keep drying out no matter how much you water them, this post is for you.

Container gardens have their advantages over in-ground gardens—you can site them where they get the best light, get the soil just right for the type of plant, or take them with you when you move—but where they come up short is in moisture control.

Plants in containers simply dry out too fast.

And it usually has nothing to do with the amount of water you give them. The soil may already feel dry to the touch by late afternoon, even if you watered plenty in the morning.

So the simplest fix is to upgrade your container size and give your plants (particularly perennials and quick-growing vegetables) more space than you think they need. Those little 6-inch pots are cute for outdoor succulents or indoor houseplants, but far too small for most plants that grow outdoors.

I see this problem most often with shrubs and vegetables: Many people underestimate how big their plants will get over the season.

While lettuce and arugula are shallow-rooted and don’t need much soil to thrive, other crops like tomatoes and zucchini are happiest in a minimum 10-gallon container or half-barrel planter. You can get away with 5-gallon containers for dwarf or “patio” types, but for most varieties, 20 gallons will buy you some time between watering sessions and help those deep-rooted vegetables live their best life.

(Bookmark my root depth chart here to find out which plants are shallow- or deep-rooted. You might be surprised!)

Although most of us choose pots based on looks, we really need to be looking at the material and color.

Unglazed terracotta and fabric grow bags dry out faster because of their porous and breathable materials. We might love them in March to keep roots from being waterlogged during cool, wet springs, but regret that decision in July when they’re not only wicking water out the top, but also out the sides of the pot.

Plastic pots and metal planters, on the other hand, tend to be thin and heat up fast in the sun, causing moisture to evaporate more quickly. And if your container garden aesthetic leans black and minimal, your plants may overheat as their roots bake against the sides of the pots on a hot summer day.

Bagged indoor potting mixes are often soilless and designed to be lightweight and highly aerated to prevent root rot in controlled environments (aka your home). In contrast, bagged outdoor potting soils are usually denser and contain organic matter like compost or manure to help retain moisture.

Both types of bagged media share a few common ingredients (peat moss, perlite, vermiculite, and others) but they differ in their ratios of these ingredients and the “extras” added to their blends (like biochar, worm castings, or mycorrhizae).

You shouldn’t use indoor potting mixes outside because they drain far too quickly. The opposite is also true: heavy, outdoor potting soils can suffocate houseplant roots and harbor pests and soil-borne diseases that get worse in indoor settings (simply because your home lacks the biodiverse ecosystem of your yard).

So don’t make this simple mistake at the store!

Read the label on the bag and make sure you buy a high-quality potting soil that’s formulated for outdoor containers. Avoid using garden soil, topsoil, or pure compost. A potting soil labeled as “all purpose” should be okay if it specifically calls out outdoor containers.

Disclosure: If you shop from my article or make a purchase through one of my links, I may receive commissions on some of the products I recommend.

Should you use inorganic moisture-retaining soil additives like hydrogels or plant crystals? Generally, I don’t recommend it.

Although these superabsorbent polymers can reduce the need for frequent watering, you do have to be sure your plants can tolerate consistently moist soil. Polymers hold moisture and release it slowly over time, which thirsty annuals might love but drought-tolerant perennials don’t need.

So, that hanging flower basket lined with sphagnum peat moss? Perfect place to use moisture-retaining polymers. But your potted Mediterranean herbs like rosemary and lavender just need a bigger pot to thrive.

To mitigate this, I’m a fan of grouping potted plants together in the yard. Not only does it create an attractive display, it makes watering easier and forms a sort of microclimate where the plants shelter each other (from sun and wind) and slightly raise the ambient humidity.

If you can’t cluster your containers, place them near existing structures that offer a bit of protection from the elements, like under a covered porch, against a building or fence, or next to trees with wide canopies.

Peat moss is notorious for being difficult to rehydrate once it’s dried out, so water tends to bead up on top of dusty soil. This is why it’s important to 1) use the correct outdoor potting soil, but also 2) never let the soil dry out completely and 3) water slowly, allowing the water to seep into the soil before you water some more.

Mulching your potted plants can absolutely help with this problem. I often just use a thin layer of straw, but if that feels a bit too rustic for your garden, you can go with more decorative materials like stones, tumbled lava, or bark mulch.

If your potting soil is already very dry though, the best way to saturate it thoroughly is by bottom watering the hydrophobic soil (rather than trying to water from the top).

This isn’t feasible for everyday watering, but if you need to revive a dried-out container plant or give your plants a thorough watering during a heat wave, a simple trick is to use a plastic kiddie pool.

Place all your pots in the kiddie pool and fill with a couple inches of water. Let the pots wick up all the moisture they need via capillary action. This may take anywhere from 30 minutes to a couple hours—the larger the pot and drier the soil, the longer it takes to bottom water.

(I’ve accidentally left my potted plants sitting in tubs of water overnight, and they were fine the next morning. So don’t worry if you forget to take them out right away!)

Once your plants are nicely hydrated, keep them that way by monitoring their moisture levels during long, hot periods. Your finger is the best “moisture meter” here; stick it in the soil a couple inches to gauge how moist it is at different times of day.

Try to water container plants early in the morning so the roots have time to absorb moisture before the day’s heat speeds up evaporation. If you need to, drench your containers a second time in the late afternoon to evening.

While it’s pretty easy to water containers by hand, it’s even easier to automate that watering with a combination of drip emitters connected to a timer.

Irrigate for however long it takes for the water to drain out the bottom of the largest pot, then let the soil dry out slightly before watering again.

Smaller pots will dry out sooner than larger pots in a drip irrigation system, but there’s no real solution to that unless you put them on different zones. So if your container garden is a mix of different sizes, be prepared to supplement with hand watering as needed.

If thinking through a drip system feels overwhelming, DripWorks (one of my longtime partners, though this post isn’t sponsored by them) offers complete “Deck Garden Irrigation Kits” that include all the parts you need to set up a drip irrigation system for your pots and planter boxes. I do recommend upgrading to the timer kits so you can make the system truly hands-free.

I used a couple of these kits when I started my container garden in California, and now I just buy the individual parts I need for my container plants in Oregon (they all use standard-sized fittings, which makes it easy to change things up).

For example, I added this small sprayer (that sprays down instead of up) to a strawberry pot with a narrow neck:

In my experience, it’s very hard to overwater containers in peak summer as long as they have drainage holes and good soil. So err on the side of giving more water in the beginning, especially if your plants are super parched, then adjust as needed.