Watering your plants properly is crucial for their health and growth. While there are general rules of thumb, how much water your plants need can vary based on the pot size, growth stage, environment, and more. In this comprehensive guide, we’ll walk through the key factors in determining the right watering approach and amount per pot size for your plants.
The Importance of Proper Watering
Before jumping into amounts, it’s worth covering why proper watering matters in the first place. If you under-water your plants, they can become stressed, stop growing, and potentially die. Over-watering has similar risks – the roots can rot leading to poor health.
Additionally, inconsistent watering causes fluctuation in moisture levels, which stresses plants out. They thrive on consistency.
Getting the right balance takes consideration of pot size, soil type, plant type, temps humidity and growth stage. Once dialed in, it allows the plant to uptake just the right amount of water and oxygen through the roots.
General Rules of Thumb for Water Amounts
While specific amounts will vary there are some general rules of thumb to use as starting points
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Seedlings – Water lightly, just 1-2 tablespoons as needed to keep soil moist. Avoid saturating.
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Small pots (<1 gallon) – Water when top inch of soil is dry. Add enough water for it to seep out drainage holes.
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Medium pots (1-5 gallons) – Water when top few inches are dry. Add water until it drains from the bottom.
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Large pots (>5 gallons) – Water when several inches deep feel dry. Add water until at least 20% drains out.
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Adjust amounts based on plant/environment. Larger, thirstier plants need more water more frequently. Hot, dry, or windy conditions increase water needs.
These are just general guidelines, but help provide a starting point for dialing in amounts. Next we’ll cover all the factors that determine exact watering needs.
Key Factors That Determine Watering Amounts
There are several key variables that affect precisely how much water your plants need per pot size:
Pot Size
Perhaps the most obvious factor is the pot size itself. The more soil volume, the more water needed to thoroughly moisten the entire root zone. Here are some starting points per pot size:
- Seedlings or propogations – 1-2 tablespoons
- 2″ seed starting pots – ~1/4 cup
- 4″ nursery pots – 1/2 to 3/4 cup
- 1 gallon pots – 1-1.5 cups
- 3 gallon pots – 3 cups
- 5 gallon pots – 4-6 cups
- 7+ gallon pots – 6-8+ cups
These volumes allow for roughly 10-20% runoff, indicating thorough watering.
Plant Type
Certain plant types are naturally more thirsty than others. Warm season annuals like tomatoes, peppers, zucchini, and cucumbers need frequent watering. Quick growing leafy greens also want consistent moisture.
Succulents, cacti, and desert-adapted plants need far less frequent watering. Over-watering these kills them quickly. Know your plant’s preferences.
Growth Stage
Younger plants need less but more frequent watering. Their small root systems absorb water quickly. At the same time, over-saturating can lead to damping off disease. Add small amounts often.
Mature, fruiting plants need the most water to support peak growth. Their large root systems allow for infrequent deep soakings.
Environment
Hot, dry, windy conditions cause moisture to evaporate faster from soil and plant leaves. This leads to quicker drying and increased needs. Cool, humid environments reduce evaporation and frequency of watering.
Likewise, full sun exposure compared to shade changes moisture loss. Watch your plants and soil closely to see impacts.
Soil Type
Soil composition affects its ability to hold and release moisture. Sandy and rocky soils won’t retain water well and drain quickly. They need more frequent watering with high-drainage plants.
Loamy soils with lots of organic material hold the most moisture. They can go longer between thorough waterings. Know your soil!
Signs It’s Time to Water Based on Pot Size
Rather than sticking to a rigid schedule, observe the visual signs it’s time to water based on pot size:
- Seedlings & small pots – Surface is dry and cracked
- 1-3 gallon pots – Surface 2″ deep is dry
- 5-7 gallon pots – Surface 4-5″ deep is dry
- 10+ gallon pots – Surface 6″+ down is dry
Additionally for larger pots, the weight provides clues. Pick up the pot to feel its weight when fully watered. When it feels much lighter, it’s time to water again.
The leaves themselves will provide clues too. If they start to droop, curl, or turn color then the plant is likely needing water. Pay close attention when temperatures rise.
Best Practices for Watering Different Pot Sizes
Beyond how much water, technique is also important:
Seedlings & Small Pots
- Water gently to avoid splashing
- Ensure even coverage without washing out soil
- Stop before saturated to prevent damping off
1-5 Gallon Pots
- Add water until it flows from drainage holes
- Allow to fully soak in, then repeat until thoroughly moist
- Lift to ensure no dry pockets remain
7-15+ Gallon Pots
- Water until 20-30% flows from the bottom
- Soak the entire root ball and center of soil
- Repeat watering in 10-15 minutes
All Pots
- Water in mornings to prevent overnight moisture
- Add moisture meters to help gauge dryness
- Adjust amounts based on seasonality
Following these best practices ensures your plants get adequate moisture without risk of under or over-watering.
Recap – Determining Water Needs Per Pot Size
Properly watering plants requires considering many factors:
- Pot size – Smaller needs less, bigger needs more
- Plant type – Some naturally more thirsty
- Growth stage – Younger vs. mature
- Climate – Hot/dry increases needs
- Soil type – Sandy drains faster than loamy
- Visual signs – Leaves, soil, weight
While general guidelines provide starting amounts, observation and adjusting as needed is key. Aim to create consistently moist yet well-drained conditions optimized to your plants’ needs.
Over time, you will dial in the ideal amounts and frequencies. Proper watering is crucial for helping plants thrive, so listen closely to what they need!
Easy Way To Calculate Your Flower Pots Volume – Measuring Your Flower Pot Size in Litres & Gallons
How much water do potted plants need?
In extreme heat, potted plants may need up to twice as much water compared with cooler weather conditions. It can be difficult to decide how much water plants in containers need since there are so many variables involved.
Do pot plants need a lot of water?
Temperature plays an important role in successful pot plant watering. When the ambient temperature is higher, plants will require more frequent watering so they are not damaged by thirst. On the flip side, when temperatures are cooler, plants need less frequent watering as their intake and use of water slows down.
How often should you water a plant in a pot?
“So a plant that’s in a 20-inch pot may only need water once every three to four weeks, whereas that same exact plan in a six-inch pot, might need water every one to two weeks. So that’s where the size of your plant and how much soil comes into play.”
How much water should you give a plant a week?
The standard rule of thumb is to give your flowers and vegetables the equivalent of 1 inch of water per week (and as much as double that amount in the peak of summer). “Stop (watering) when the soil is moist but not waterlogged,” Pappas adds. 3. DO water plants at soil level.