Cactus & Succulents: Top or Bottom?

Of course! This is an excellent question and a key technique for successfully growing cacti and succulents.

“Top of bottom watering” isn’t a standard term, but it refers to the highly effective method of Bottom Watering. This is often considered the best practice for these plants.

Here’s a complete breakdown of what it is, why it’s great, and how to do it properly.

What is Bottom Watering?

Bottom watering, sometimes called the “soak and dry” method, involves placing your potted plant in a container of water and allowing the soil to absorb moisture from the bottom up through the drainage holes, rather than pouring water over the top of the soil.

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Why Bottom Watering is Perfect for Cacti & Succulents

1. Prevents Root Rot: The most common killer of cacti and succulents is overwatering. Top watering can sometimes leave the top inch of soil wet while the root ball remains dry. Bottom watering ensures the entire root system gets evenly and thoroughly hydrated, encouraging deep, strong roots.
2. Avoids Water on Leaves and Stems: Many cacti and succulents (like Echeveria) are prone to rot if water pools in their crown or on their leaves. Bottom watering keeps the plant itself completely dry.
3. Prevents Soil Compaction: Top watering can pound down the soil over time, reducing aeration. Bottom watering allows the soil to wick up water gently without disturbing its structure.
4. Flushes Out Salts: As water moves up through the soil, it helps push excess mineral salts (from tap water and fertilizer) toward the surface, where you can see them as a white crust. You can then scrape this crust away, preventing root burn.

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How to Bottom Water Correctly: A Step-by-Step Guide

What You’ll Need:

• Your plant in a pot with a drainage hole (this is non-negotiable).
• A sink, tub, or tray larger than your plant’s pot.
• Water (room temperature is best).

Steps:

1. Check the Soil: First, always check if the plant actually needs water. Stick your finger or a wooden skewer into the soil. If it’s completely dry all the way to the bottom, it’s time to water.
2. Prepare the Water: Fill your sink, tub, or tray with enough water to reach about 1/3 to 1/2 the height of your pot.
3. Place the Pot In: Set the plant pot directly into the water. Do not pour water into the top of the pot.
4. Wait: Let the pot sit in the water for 15 to 30 minutes. You’ll see the water level go down as the soil absorbs it. For a very dry, peat-based soil mix, it might take longer. The top surface of the soil will become visibly moist.
5. Remove and Drain: Once the topsoil is moist, take the pot out of the water. This is crucial—let it drain completely in the sink or on a rack until no more water drips out from the bottom. Do not let it sit in the runoff water.
6. Return to its Home: Once fully drained, place your plant back in its sunny spot.

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When to Use Top Watering (The Exceptions)

While bottom watering is ideal, there are times when top watering is necessary or useful:

• To Flush Soil: If you see a large buildup of white mineral salts on the soil surface, it’s a good idea to occasionally water thoroughly from the top to help flush those salts out through the drainage holes.
• For Very Large, Heavy Pots: It can be impractical to move a large, heavy pot into a tub for bottom watering.
• If the Soil Has Become Hydrophobic: If the soil is so dry that it repels water, bottom watering might not work. In this case, you may need to water gently from the top first to break the surface tension, or submerge the entire pot for a longer period.

Key Takeaway

For the health of your cacti and succulents, adopt the “Soak and Dry” method using bottom watering.

1. Soak thoroughly (from the bottom).
2. Let it Drain completely.
3. Let it Dry out completely before you even think about watering again.

This cycle mimics the natural desert rains these plants are adapted to, leading to a much healthier and happier plant.