Self Watering Planters
Self watering planters cut watering frequency by 50–75% and prevent overwatering that kills container plants. Here's how they work and which to buy.
Key takeaways
- Self watering planters use a water reservoir below the growing zone — plants draw water up through capillary action from roots downward to the wet zone
- Most models need to be filled every 5–10 days instead of daily, depending on plant size, season, and heat — roughly 50–75% less frequent than conventional pots
- The reservoir prevents the boom-and-bust wet-dry cycle of hand watering, producing healthier roots and higher yield in vegetables
- Do not fill the reservoir in winter for outdoor containers — standing water in a freeze-thaw cycle cracks most reservoir designs
- Self watering planters work best for vegetables, herbs, and annuals — they're less ideal for succulents and cacti that need dramatic dry-out periods
How self watering planters work
A self watering planter has a water reservoir built into the base below the main growing zone. Plants draw water upward from the reservoir through capillary action — the same mechanism that makes paper towels absorb water. Roots sense moisture and grow toward it, accessing water on demand rather than waiting for the next watering cycle.
The design eliminates two problems that affect most container plants:
- Overwatering: hand-watered containers are often kept too wet, leading to root rot
- Underwatering: plants that miss a day of watering during heat experience drought stress that causes blossom drop, bitterness, and reduced yield
Sub-irrigation keeps the growing medium at consistent moisture throughout the root zone — neither wet at the top nor bone-dry between hand-waterings.
Most self watering planters include a water level indicator (a float or sight tube) that shows when the reservoir needs refilling. The fill point is typically a tube on the side of the planter that lets you add water directly to the reservoir without disturbing the roots above.
Types of self watering planters
| Type | Best for | Average cost | Notes |
|---|---|---|---|
| Window box (self watering) | Herbs, trailing flowers, lettuce | $25–60 | Common for railings and windowsills |
| Round pot (6–14 inch) | Single tomatoes, peppers, houseplants | $20–50 | Most common type |
| Large trough (24+ inch) | Multiple vegetables; bush tomatoes | $60–150 | Good for balcony food production |
| Fabric raised bed with reservoir | Multiple vegetables; heavier production | $80–200 | Lightweight; combines raised bed with sub-irrigation |
| Earth Boxes and clones | Tomatoes, heavy vegetable production | $60–100 | Long-track record; 5-gallon equivalent |
| Hanging basket (self watering) | Petunias, trailing plants | $20–40 | Good for outdoor color; needs frequent reservoir fill in heat |
What to grow in self watering planters
Self watering planters excel for moisture-loving plants that need consistent soil moisture.
Excellent choices:
- Tomatoes (especially determinate types like Celebrity or Patio)
- Peppers and bell peppers
- Lettuce and salad greens
- Herbs (basil, parsley, cilantro, chives)
- Cucumbers (compact/bush varieties)
- Strawberries
- Petunias, impatiens, and most container annuals
- Houseplants (tropical types like pothos, philodendron, ferns)
Poor choices:
- Succulents and cacti (need complete dry-out between waterings)
- Mediterranean herbs like rosemary, lavender, and thyme (need dry conditions)
- Root vegetables (carrots, beets) that need deep, consistently uniform soil for proper root formation
For growing tomatoes in self watering containers specifically, our how to grow tomatoes in pots guide covers variety selection and soil setup for the best results.
Choosing the right size self watering planter
Planter size determines root volume and therefore maximum plant size and yield.
| Plant | Minimum reservoir size | Recommended size |
|---|---|---|
| Cherry tomato | 5 gallon | 10 gallon |
| Full-size tomato | 10 gallon | 15–20 gallon |
| Bell pepper | 5 gallon | 7–10 gallon |
| Lettuce (single) | 1 gallon | 2 gallon |
| Basil | 1 gallon | 2–3 gallon |
| Cucumber (bush) | 5 gallon | 10 gallon |
| Strawberry | 1 gallon per plant | Strawberry tower |
The most common mistake is choosing too small a container. A tomato plant in a 5-gallon self watering planter produces significantly less than the same variety in a 15-gallon container.
How to set up a self watering planter
Fill the growing zone with potting mix — not garden soil — that has good wicking ability. Then fill the reservoir from the fill tube, not from the top of the soil.
Step-by-step setup:
- Add potting mix to the growing zone, filling to 1–2 inches below the rim
- If there’s a soil column or wicking basket that connects the grow zone to the reservoir, fill it with damp potting mix
- Plant seedlings or seeds in the growing zone as normal
- Water from the top for the first 7–14 days to help roots establish in the growing zone and begin making contact with the wicker/wick mechanism
- After the first 2 weeks, switch to filling only the reservoir via the fill tube
- Check the water level indicator and refill when it reads low or empty
First fill timing: don’t fill the reservoir until roots have grown down into the lower growing zone. Filling too early (in the first week) doesn’t help plants that haven’t grown roots down to the wick yet.
Soil choice for self watering planters
Use a light, high-quality potting mix with good capillary action. Heavier mixes wick poorly; mixes with good perlite or coir content wick more effectively.
Recommended mixes:
- FoxFarm Ocean Forest: well-balanced; good wicking; nutrient-rich base
- Miracle-Gro Moisture Control: formulated for container water retention; widely available at US garden centers
- Custom mix: 60% standard potting mix + 30% perlite + 10% vermiculite — excellent wicking and drainage
Avoid: garden soil (too dense, doesn’t wick), straight perlite (no nutrition), or mixes with excessive bark (bark floats and disrupts wicking in wet conditions).
Fertilizing self watering planter plants
Plants in self watering containers need regular fertilizing — the reservoir only delivers water, not nutrients.
Fertilizing schedule:
- At setup: incorporate a slow-release granular fertilizer (like Osmocote 14-14-14) into the potting mix
- Every 2–4 weeks in growing season: add water-soluble fertilizer to the reservoir or to the growing zone surface
- For vegetables: use a tomato fertilizer or vegetable-specific formula during fruiting
- For flowers: switch to a bloom-booster formula (lower nitrogen, higher phosphorus/potassium) once buds form
Do not over-fertilize — with consistent moisture, plants in self watering containers grow vigorously and can show fertilizer burn at rates that conventional pots handle without problem.
Self watering planters for balconies and small spaces
Self watering planters are particularly valuable for balcony gardening because:
- Reduced watering frequency reduces the need to be home daily in summer
- Less water dripping from planters (water is absorbed from below, not poured from above)
- Higher yields per square foot compared to conventional containers
- Weight can be managed by choosing lightweight potting mix and resin containers
Weight considerations: a 10-gallon self watering planter with moist potting mix weighs 35–50 lbs. Check the load rating of your balcony (typically 40–60 lbs per square foot for US residential construction) and stay within safe limits.
For full guidance on setting up a small-space food garden using containers and self-watering planters, our container gardening small spaces guide covers layout, plant selection, and soil mix for balconies and patios.
Seasonal care and winterizing
In winter, drain the reservoir completely before freezing temperatures arrive. Most self watering planter reservoirs are plastic and will crack when standing water freezes. A cracked reservoir cannot be repaired — prevention is essential.
Winterizing steps:
- Remove plants from the planter in fall before the first hard frost
- Empty the reservoir by inverting the planter, using the drain plug, or removing the wick/wicker
- Store the empty planter indoors or in a garage for winter
- Clean the reservoir interior with a diluted bleach solution (1 tablespoon bleach per gallon water) to prevent algae and mineral buildup
For outdoor use in Zone 9–11 where soil doesn’t freeze, self watering planters can remain active year-round. In Zone 7–8, drain before the average first hard freeze (typically November).
Top self watering planter brands available in the US
- Lechuza: German-engineered; high quality; 15+ styles; available at US garden centers and online
- Earth Box: long-track record for vegetable production; high-yield design; sold at major US retailers
- Self Watering Planter by Classic Home and Garden: good value; widely available on Amazon
- Window boxes by Bloem: window-box style; good for herbs and lettuce; widely available
- Fabric-reservoir beds by Root Pouch: combines raised bed and sub-irrigation
For US purchasers, most of these are available through Amazon, Home Depot online, or specialty garden retailers. Prices range from $25 for a small pot to $150+ for large fabric-reservoir systems.
Sarah Mitchell is a Master Gardener and garden writer based in the Pacific Northwest. She has been growing food and flowers for over 15 years across USDA zones 7 and 8.