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How Often to Water Seedlings

A big part of growing a successful garden is knowing how often to water seedlings. At their young stage, seedlings need water to create energy to grow. If you’re not careful, it can be easy to under or overwater seedlings.

Keep reading to learn about how often to water seedlings. We’ll also go over the best ways to keep your seedlings hydrated. Let’s dive in!

Closeup of watering seedlings. Knowing how often to water seedlings is critical for healthy plants.

How Often to Water Seedlings

There is no definite answer on how often to water seedlings. Although, I recommend always checking on your seedlings once per day.

For one gardener, watering every other day might work. But, that may be too often or not enough for another gardener.

It all depends on the seedling’s environment. You’ll need to look at the temperature of your seed starting setup. You’ll also need to consider your seed starting mix and whether or not you’re using a heat mat.

First, let’s talk about temperature. Seeds can be started anywhere in your home as long as they have sufficient lighting. You may be using a spare room or your garage/basement.

Starting seeds indoors under grow lights.

When using a spare room, seedlings are usually kept around 70 degrees. They will probably dry out quicker than seedlings kept in a chilly garage or basement. In this case, you need to water seedlings at least once daily.

No matter where you keep your seedlings, they will dry out quickly when you use a heat mat. That’s because heat mats warm the soil to mimic ideal outdoor temperatures. If you have a heat mat, check your seedlings for dryness and water one to two times per day.

Lastly, if you have a well-draining seed starting mix, seeds will dry out quicker than a heavy potting mix. Check well-drained seedlings once per day for dryness.

How to Check for Dry Seedlings

Now that you know how often to water seedlings, let’s go over how to inspect for dry seedlings.

Feel the Soil

Woman checking the soil moisture for a seedling.

The surest way to detect dry soil is by feeling the top half-inch of soil or seed starting mix. If the soil is dry and easily movable, your seedlings need water!

If the soil feels wet and dense, your seedlings are good for now. You should check back later that night or in the morning.

Observe the Color

Closeup of a newly sprouted seedling in moist seed starting mix.

If you are simply glancing over your seedlings, you can detect dryness by observing the color of the soil. Dry soil is light brown and fluffy, while wet soil will be dark brown and compacted.

If your soil is wet every time you visit your seedlings, you have drainage issues. Avoid using heavy potting soil for starting seeds. And, make sure there are holes for drainage in your seed starting trays.

Tips on Watering Seedlings

Water from Underneath

The best method for watering seedlings is by watering them from underneath. This ensures that the entire root system is being hydrated.

When watering seedlings from above, you could potentially only hydrate the top layer of soil. And, you may not even notice it since the top of the seedlings appears wet.

Watering from underneath allows seedlings to soak up water like a wick. As they sit in the water, the seedlings absorb as much water as they need.

Once you remove the seed starting trays from the bottom tray, excess water will drain. So, you’re avoiding overwatering, as well!

A bottom tray for a seed starting tray.
A bottom tray for seed starting trays.

To water seedlings from underneath, you’ll need a bottom tray with no holes. Fill the bottom tray with at least one inch of water. Set your seed starting trays in the bottom tray, and set your timer for 30 minutes to an hour.

Once the time is up, remove the seed starting trays, and drain the remaining water from the bottom tray. Once you’ve drained the tray, you can return the seed starting trays to the bottom tray for a brief time. This allows them to shed excess water.

Use a Narrow Spout

If you don’t have access to a bottom tray, you can still water your seedlings from above. Use a watering can that has a narrow spout.

I recommend searching for a watering can made for houseplants. These are often small, and the spouts are made to fit into tight spaces.

Person using a houseplant watering can to water seedlings.

A slender spout will allow you to water the seed starting mix at the surface. Since seedling leaves are often weak, they cannot withstand damage from water droplets.

Water the seed starting mix a little at a time. The mix will need to soak in the water before you apply more. If you apply too much water at once, the seed starting mix may run out of the tray.

Like watering seedlings from underneath, you may want to put a pan under the trays to catch any excess water.

How to Keep Seedlings Adequately Hydrated

If you feel you are watering seedlings too frequently, there are a few ways to help keep seedlings hydrated.

Thin Out Seedlings

A starter tray of broccoli seedlings.

If you haven’t thinned out your seedlings, you could have several seedlings competing for water in one cell.

The more seedlings per cell, the more complicated the root system. The roots will quickly soak up more water to provide hydration to all the existing seedlings.

If your seedlings have already developed a true set of leaves, you can begin thinning them out. The true leaves are the second set of leaves that come after germination. They will resemble the leaves of a mature version of that vegetable or flower.

Choose the seedling that appears the healthiest, and thin out the rest. You should keep one seedling per cell.

You can thin seedlings by cutting them at the soil’s surface with narrow pruning shears. Or, you can remove them by hand if the roots are not too entangled.

To learn more about thinning seedlings, read our blog post, When to Thin Seedlings.

Adjust Your Grow Lights

Seedlings under a grow light.

If your grow lights are too close to your plants, seedlings may dry out quicker than they should.

Depending on the bulb you’re using, some grow lights get warm when left on all day. This has the same effect as a heat mat and can warm up and dry the soil quickly.

Adjust grow lights to stay at least six inches above seedlings. Using LED lights will also help as they are prone to stay cooler than incandescent bulbs.

Watch the Temperature

Whether you’ve been cranking up the thermostat or are experiencing a warm spring, temperature plays a big part in seedling hydration.

Make sure to keep seedlings at 60 to 70 degrees for ideal conditions. This will lessen how often to water seedlings.

If you cannot reduce the temperature, running a small fan will help. Just make sure to point the wind flow from blowing directly onto seedlings. This could dry them out quicker than high temperatures.

Closeup of an electric fan.

Have Proper Drainage

Having proper drainage will prevent waterlogged seedlings. If you’re only watering seedlings once a week, you probably have a drainage problem. This can be caused by a lack of drainage holes or improper seed starting mix.

All seed starting trays should contain drainage holes at the bottom. This lets seedlings easily drain off any excess water.

If your seedlings have drainage holes but aren’t draining, you may need to poke a pencil in the hole. It could be blocked by a large piece of bark or compost.

A seed starter tray and a bottom tray.

If seed starting trays don’t contain holes, you should only water them once the top layer of soil is dry.

Improper drainage can also be caused by not using seed starting mix. The ideal seed starting mix is made from soil-less ingredients known for their draining properties. Examples include peat moss, perlite, and vermiculite.

Use one of these best seed starting mixes, or save money and create your own.

Avoid using potting soil or soil mixes made for your flower bed. These often contain heavier ingredients and don’t drain as well as seed starting mix.

FAQs on Watering Seedlings

Watering seedlings in pots.

1. Can I save overwatered seedlings?

Yes, you can save overwatered seedlings. Whether you’ve been watering seedlings too frequently or can’t get them to drain, you’re not out of luck yet.

As soon as you detect waterlogged seedlings, you will need to change the conditions of the seedling’s environment.

Move the seedlings to a warmer area with plenty of airflow. This will help them dry out.

It could be helpful to sit your seedlings outdoors on a warmer day for 30 minutes to an hour. Or, temporarily move them to your living room, and run a fan.

You will also need to create drainage if you don’t already have it. Poke holes in your seed starting trays, or clear out any large debris blocking drainage holes.

2. Can I save underwatered seedlings?

Saving underwatered seedlings is possible if the seedling is not already on its way out. If the seedling is completely wilted and turning colors, you can safely assume it’s time to sow new seeds.

If the seedling still looks mostly healthy, you will need to soak the seedling in water. Sit the seed starting tray in a bottom tray or pan. Fill the tray with one inch of water and let the seedling soak up water for up to an hour.

Keep an eye on the seedling. You may need to repeat this process a couple of times per day.

Wrapping Up How Often to Water Seedlings

Watering seedlings with a small watering can.

Knowing how often to water seedlings can save you from some headaches down the road. Assess the temperature and heat being applied to seedlings, and check on seedlings frequently. You’ll be ready to transplant your seedlings to the garden before you know it!

For more helpful information on starting seeds successfully, visit our Seed Starting Page. We’ll help you get a jump start on this year’s garden. And, we’ll let you know which products are the best to use.