Bottom watering is an alternative method of watering plants that delivers water directly to the roots from below, rather than pouring water onto the top of the soil. This technique has several benefits for plant health and growth.
What is Bottom Watering?
Bottom watering involves placing the pot in a tray or dish of water and allowing the soil to soak up the moisture from below. The water is absorbed through drainage holes in the bottom of the pot. This allows the water to thoroughly saturate the soil without overflowing the pot or spilling over.
Some key things to know about bottom watering:
- It is sometimes called reverse watering or sub-irrigation.
- The plant pot must have drainage holes for the water to soak upwards.
- The plant is placed in a dish or tray with enough water to partially submerge the pot.
- Water is drawn up into the soil through capillary action and saturates the root zone.
- The plant is allowed to soak for a period before removing from the water.
Why Bottom Water Your Plants?
Bottom watering has several advantages that can promote healthier, more vigorous plants:
Encourages Deep Root Growth
By saturating the entire soil area, bottom watering encourages plants to grow deep, sturdy root systems that can better access water and nutrients. Shallow watering from the top often results in shallow root growth.
Avoids Foliage Wetness
Watering from below prevents moisture from collecting on leaves and stems. This helps reduce foliar diseases and pests like powdery mildew, which thrive on damp leaves.
No Runoff or Evaporation
Bottom watering delivers water directly to the roots, minimizing water loss through runoff or evaporation from the soil surface. This helps conserve water.
Oxygenates Soil
As the previously dry upper layers of soil absorb the rising water, air pockets open up, oxygenating the root zone. Plant roots need oxygen!
Less Transplant Shock
Soaking transplants by bottom watering before planting helps sustain moisture in the root ball, reducing transplant shock.
Minimizes Mineral Buildup
Water wicked up from below leaves mineral salts behind in the drainage tray. This prevents fertilizer and mineral accumulation on the soil surface.
Promotes Strong Starts
Bottom watering keeps surface soil dry, preventing crusting. This helps seedlings emerge successfully.
How to Bottom Water Your Plants
Bottom watering takes a little practice but is easy once you get the hang of it. Follow these steps:
Choose an Appropriate Container
The plant must be in a pot with drainage holes to allow water uptake. Plastic and ceramic pots work well. Avoid pots without holes like terracotta.
Fill Reservoirs with Water
Place pots in sinks, buckets, tubs, or trays filled with adequate water to submerge the bottom inch or two of potting soil. Don’t let pots sit in excessive water.
Allow Time for Absorption
Let the pots sit for 20-30 minutes to fully saturate. Lift occasionally to check water absorption progress. Soak time depends on soil porosity.
Remove & Drain
Once the top of the soil is moist, remove the pots and allow excess water to drain completely before returning the plants to their spots.
Water When Soil Dries
Let the soil dry out nearly completely before bottom watering again. The top inch can feel dry while soil below remains moist.
Adjust Amount of Water
For the next soaking, adjust water amount – increase if soil took a long time to get wet, decrease if soil became fully saturated quickly.
Tips for Bottom Watering Success
Follow these tips to get the most out of this method:
- Water early in the day to allow pots to drain before nighttime.
- Soak new transplants by bottom watering to establish without shocking.
- Try soaking seed flats by bottom watering to sprout seeds.
- Water pots on water-absorbing mats to pull moisture up from underneath.
- Use trays or dishes that hold just enough water to partially submerge pots.
- If soil floats up, break up surface tension by stirring water before placing pots.
- For houseplants, put pebbles or stones in cache pots before adding water.
When Bottom Watering Works Best
While suitable for most plants, bottom watering is especially beneficial for:
- Root crops – Like carrots, beets, and radishes. Produces straight, unbranched roots.
- Vegetables prone to foliar diseases – Keeps moisture off leaves of squash, cucumbers, melons.
- Seedlings and transplants – Encourages extensive root growth right from the start.
- Potted plants – Efficiently hydrates container plants while minimizing diseases.
- Succulents – Saturates soil thoroughly despite sporadic deep watering.
- Drought-tolerant plants – Allows dry surface while roots access moisture.
Potential Drawbacks to Bottom Watering
Bottom watering has many advantages but may not be ideal for all situations:
- May take longer than top watering for large-scale watering.
- Requires plants to be in drainage pots and ability to move them.
- Not practical for raised beds and in-ground plants.
- Can leave salt residue in drainage saucers of potted plants.
- Excess watering can saturate soil for too long.
- Plants like cacti and succulents may prefer less frequent soakings.
The Takeaway
When used properly, bottom watering is an excellent way to provide complete moisture to plants without compromising foliage health. The thorough hydration encourages expansive roots and stronger plants. This simple shift in watering method can make a big difference for many types of potted plants!
Frequently Asked Questions About Bottom Watering
Bottom watering is an alternative irrigation technique that offers some unique benefits. Here are answers to some commonly asked questions about bottom watering houseplants and garden plants.
What types of plants can I bottom water?
Most plants can be bottom watered, including vegetables, herbs, perennials, annuals, and container plants. It works especially well for potted houseplants and transplanted seedlings. Plants with very fine, shallow roots may not be good candidates.
How often should I bottom water my plants?
Bottom water whenever the soil is mostly dry. For potted plants, check the moisture level about 1-2 inches below the surface before watering again. The frequency depends on factors like plant size, climate, and season.
Is it okay to bottom water succulents and cacti?
Yes, bottom watering is a great technique for succulents and cacti. It allows you to provide a thorough soak while still allowing the soil surface to dry out quickly. Just make sure to allow extra time between waterings.
How long should I leave my plant to soak?
Most plants only need about 20-30 minutes to uptake adequate water from bottom watering. Lift the pots periodically to check soil moisture. Remove promptly once the top few inches of soil are wet. Extended soaking can saturate soil excessively.
Can I bottom water houseplants while they’re still in decorative pots?
Yes! Just place the entire decorative pot in a container of water, allowing the soil to absorb moisture through the drainage holes in the nursery pot. Monitor water levels carefully to avoid overflow.
Should I fertilize when bottom watering?
Bottom watering can help prevent buildup of fertilizer salts. You can add diluted liquid fertilizer to the watering vessel, allowing plants to uptake nutrients from below. Otherwise fertilize as normal.
Is bottom watering good for seed starting?
Bottom watering is an excellent way to keep seed starting mix evenly moist without disturbing seeds. Use shallow trays and wick moisture up from below. Just make sure mixes drain well.
Can bottom watering prevent transplant shock?
Yes! Gently bottom watering transplants right after planting helps sustain moisture in the root ball, preventing excessive wilting. It establishes young roots without shocking plants.
What kind of container should I use to bottom water?
Use any water-tight vessel that allows you to partially submerge the pot, like buckets, tubs, trays, sinks, or pans. Make sure pots have drainage holes for water intake and that plants sit above excess water.
Conclusion
Bottom watering is a simple yet highly effective way to thoroughly hydrate plants by saturating the soil from below. Allowing moisture to wick upwards encourages deep root growth, oxygenates soil, and reduces disease risk compared to traditional top watering. While not suitable for all situations, bottom watering excels at establishing transplants, container plants, vegetables, and many other plant types with minimal effort. With proper technique, the benefits of bottom watering are considerable for plant health and vigor. Paying attention to factors like soil absorption rates, water amounts, and timing is key to success. But once mastered, this upside down watering approach often proves to be a game changer for indoor and outdoor growers alike.