Watering Seedlings: Best Techniques & How Often to Water

Hey all! Real Farmer Jeff here.

Caring for little seedings sometimes feels like taking care of a baby because they can also be fragile and hard to read. Too much water can drown the seedling’s roots or cause disease, while too little can stunt their growth or cause wilting.

It is crucial that you learn good watering techniques so that your seedlings have the best chance for prolific growth!

Below I outline how I water my seedlings, the best techniques, how often you should water, and common mistakes to avoid so you can give your young plants the best possible start.

Pay special attention to the pros and cons of top watering vs. bottom watering! This will ensure you the best results for your seedlings.

Let’s get started!

Frequency of Watering

Seedlings need consistent moisture, so check on them once a day and water as needed. Alternatively, you can give a heavier watering so that you only have to water every couple of days. I personally like to water daily to build the habit, so I don’t forget.

Seedlings should not sit in soggy soil, but the top of the soil should feel slightly damp. If the soil feels dry an inch below the surface, it’s time to water.

In a warm, dry environment (e.g., in direct sunlight), you may need to water twice a day. Additionally, if you have an oscillating fan on your seedlings to promote root growth, this will also cause the soil to dry out more quickly.

In cooler or more humid conditions, you might only need to water every other day.

How to Check Soil Moisture

Touch Test: Stick your finger about 1 inch (2.5 cm) into the soil. If it feels dry, then it’s time to water. If it’s still moist, then wait until it dries slightly before watering. The goal is to have the soil moist and not dry or soaking wet.
Seed Tray Observation: Since the liners of my seed trays are clear I will sometimes lift them up to see how the soil looks. It is usually pretty easy to visibly see how dry the soil is.

Recommended Seed Trays

Watering Techniques

Top Watering: This method involves watering seedlings from above, either by using a watering can or spray bottle (pictured).

Pros:

Easier: Requires no extra setup; just pour water over the soil.
Helps wash away salts: Prevents salt buildup from fertilizers by flushing them out of the soil.
Mimics natural rainfall: Provides a more natural watering approach, which can be beneficial for plant growth.
Adds humidity: Can slightly raise the humidity around the seedlings, which some plants benefit from.

Cons:

Risk of overwatering: It’s easy to drench the seedlings, leading to soggy soil and root rot.
Can disturb the soil: A strong flow of water may displace seeds or compact the soil.
Increases disease risk: Leaves and stems staying wet for too long can encourage fungal diseases like damping-off.
Uneven moisture distribution: Some areas of the soil might dry out faster than others.

Bottom Watering: This method involves placing seed trays or pots in a shallow tray of water, allowing the soil to absorb moisture through the drainage holes. With my seed trays, I remove the inserts (pictured), fill the bottom tray with about an inch of water, then place the insert back.

This method works especially well if you use a seed starting mix that absorbs water well and can wick the water upward. Common seed-starting components that retain water well are vermiculite (this also prevents fungal diseases!) coco coir, and peat moss.

Pros:

Encourages strong root growth: Roots grow deeper as they search for water, making seedlings more resilient.
Prevents damping-off: Since water isn’t sitting on the leaves or stems, there’s a lower risk of fungal diseases.
Even moisture distribution: Ensures that the entire soil profile is consistently moist.
Reduces soil disturbance: No risk of washing away seeds or compacting soil.

Cons:

Takes longer: The absorption process is slower.
Can lead to salt buildup: Since water isn’t flushing from the top, minerals from fertilizers may accumulate in the soil.
Requires proper drainage: If the potting mix doesn’t drain well, it can lead to stagnant water and root rot.
Extra setup needed: Requires trays or containers to hold water.

Which Method is Better?

It depends on your setup and plant needs:

Use top watering if you’re regularly monitoring moisture levels and need to flush salts.

Use bottom watering if you want to encourage strong root development and reduce disease risk.

Best approach? A combination of both! Start with top watering when seedlings are very small, then switch to bottom watering as they establish. Occasionally top water to rinse the soil.

Signs of Underwatering or Overwatering

Underwatering: Wilting, dry, brittle leaves, soil that’s completely dry to the touch.
Overwatering: Yellowing leaves, wilting despite wet soil, mold or fungus growing on the soil surface, or seedlings that are “drowned” in soggy soil.

Learning how to water seedlings is easy! Fortunately, seedlings can tolerate a fairly wide moisture range, reducing the risk of killing them. However, watering the right amount can help your plants to stretch their roots to find water and can contribute to healthier plants down the road.

Best of luck taking care of your seedlings this year! If you enjoyed this blog post, be sure to check out my other gardening blog posts:

realfarmerjeff

Jeff has a deep passion for gardening. Each year, he cultivates hundreds of pounds of vegetables—along with the occasional fruit—turning his garden into a thriving and productive space. Combined with Kyrié’s cooking, together, they create exciting meals using Jeff’s harvest.