Also, the sheer number of plants we own made commercial solutions too expensive. I considered building a system with tubing, but my husband worried that it might spring a leak while no one was home.
So I came up with the following dirt-cheap, easy, and fairly leak-proof solution: You just need resealable plastic bag full of water with a wick in it to pull the water out at steady rate.
This Instructable will show you how to do that, but all you really need to know is that the size of the needle you use to thread the wick determines how fast the water drains out of the bag.
Caveat: Not all plants will be happy with this method of watering, which keeps the soil continuously damp. Ivy, for example, likes to dry out before being re-watered.
Step 1: What You'll Need:
1) Thread. Most types will work, but cotton thread is probably best for wicking purposes. If you're going away for a very long time, polyester might be better to ensure the thread doesn't rot.
2) Scissors for snipping thread.
3) Re-sealable plastic bags. The size depends on how large a reservoir of water you need, which will depend on how much water you want to deliver to the plant every day, and for how many days.
4) A very fine needle. The ideal is probably a #10 needle, which is about 0.5mm = 0.02" thick. However, any needle in the #8 - #12 range should work fine.
NOTE: A "regular" needle is usually about a #6 and TOO LARGE. The size of the needle is what determines how fast the water will drain, so you must find a very thin one. It's easy to add more threads to one bag to increase the drainage rate, or to add several small bags to one plant's pot, but you can't throttle the water flow from a hole that is too large.
Step 2: What You'll Need to Think About in Advance:
1) How much water does each of your plants need?
What you want to determine is how much water you want draining into the plant per day. The way to work this out is to think about how much water you normally give that plant and how often.
For example if you usually give your plant two cups of water once a week, then you want your bag to deliver (2 cups / 7 days) ~ 0.29 cups of water to the plant every day.
2) How large a plastic bag are you going to need to hold enough water to last your entire trip?
For example, if your plant needs 0.29 cups of water per day, and you're going to be gone for 20 days, then you want a bag that will hold (0.29 cups per day) x (20 days) = 5.8 cups of water.
On our last trip, I only used "snack" and "medium" sized Ziploc bags, so I can give you the water volume of those:
- "Snack" sized Ziploc bags (4" x 6.5"): 1 cup of water
- "Medium" sized Ziploc bags (7" x 9"): slightly less than 6 cups of water
3) How fast are your bags actually draining?
Obviously you're going to need to actually create a bag to determine this, but you should test how much water drains out of the bag over a given time period. This will depend on the size of needle you use.
To test your drainage rate, create a bag with one wick, then fill it with water and prop it on the top of a measuring cup with the wick pointing downward. Wait an hour, then see how much water has dripped into the cup. Multiply this by 24 hours to find out how much water the bag will deliver in one day.
If it isn't enough, then you can add more wicks to the bag. As long as you use the same needle, you can double, triple, etc., the flow rate in a very consistent manner.
Step 3: Preparing Your Water-wick
Tie the two ends of the thread together with a fairly large knot (i.e. knot it two or three times in the same location.) The bag's plastic is quite soft, and small knots sometimes slip right through the hole that the needle makes.
Step 4: Adding the Wick to the Water Reservoir
Note that the thread is NOT optional; the flow rate of the water becomes very inconsistent if you don't have a wick holding the hole open.
I like to put the wick near the bottom of the bag, centred, but also going through one of the flat sides of the bag. That way, I can lie the wick directly against the plant's soil when the bag is full of water.
It's important you don't poke extra holes in the bag by accident as you're moving the needle down to the bottom, so I recommend pressing the tip of the needle flat against your finger (as shown in the first photo) before moving your hand into the bag.
Once you get the needle to the place where you want to place the wick, push the needle through the bag, then snip the thread.
And that's it! You're ready to use the bag.
Step 5: Preparing to Use the Magical Plant-watering Leaky Baggie
Hold the bag open and dip it into the water, then lift it slightly to let gravity fill it. To get the maximum amount of water into the bag, I find it's easiest to seal it with the bag still mostly underwater.
Because the bag is now actively leaking, transfer it into a pan or bowl so you can take it to your plant without dripping on the floor.
Step 7: Water Your Plants!
If you need to deliver more water to a particular plant, you can either add more wicks to one bag, or add more bags to that plant's pot.
Large bags may need to be propped up via kebab skewers or chopsticks to ensure the bag doesn't flop over the edge of the pot as it deflates, isolating some of the water in a pocket that can't drain.
When you get home from your trip, empty the bags, let them dry out, then roll them up and store them for your next vacation. They take up very little space.