wiring multiple led flashlights to single power source
Let's try and derive a simple answer for you, that can be understood without EE level math.
I assume that the torches you are using are White LEDs. If they are White then I would expect a forward voltage of about 3-3.5 V for the devices used.  



All diodes have a slope in the Vf characteristics such that as the current through them increases, the forward voltage drop increases (in a non-linear fashion) too. You can see from the above graph that at a current of 5 mA for a White LED, Vf is about 3 V and at a current of 27.5 mA it's about 3.5 V.   

The typical cheap Torch is powered by 3 * 1.5 V batteries, so the voltage available ranges from 4.5 V for fresh batteries to about 3 V for fully discharged batteries (1 V per cell). The brightness of the torch will drop as the batteries discharge. 
So again an assumption; you may be talking about cheap 24 LED torches such as this: 
 

If this is indeed somewhat similar to your torch, then you have the series resistor wrong. It's more likely to be 2.2 Ohms than 22 Ohms. I have a bunch of these type torches and in mine the resistor is 2.6 Ohms.

To figure out how much current is flowing in 24 parallel LEDs is a bit of heavy math lifting to be accurate, but we can derive an approximation of the current in a very simple manner using just the graph above. 

Here is the graph re-done to show the current and Vf for 24 LEDs in parallel.  Superimposed on this is the linear slope representing the current/voltage of the 2.2 Ohms limiting resistor I assume is in your torches. 



The graph depends on a couple of assumptions:


The diodes are all identical Vf curves. ....they won't be, but they will be close enough to make this work. 
Linear characterization of the Vf curve is good enough for an approximation of the total torch current. 


From the above graph you can see that when the battery voltage is 4.5 V the current (LEDs and resistor) will be approximately 660 m A, and when the battery voltage is 3.5 V the current will be approximately 240 mA. 

The power dissipation for a torch is then V * A --> 4.5 * 0.660 = 3 W. 
So each LED (if they shared the current equally) would be about 27.5 mA. This is about right as a maximum current for these small sized LEDs.   

With your 30 torches at 3 W each you now also know you need about 90 W of power in total.

If you want to run 30 torches in parallel (using say a larger power supply to provide 4.5 V), then you'd have current flows of about 0.66 * 30 = 20 A. This could be done, but I consider it impractical (size of cables and voltage drop).  

Now lets flip over to your garden situation. Most local regulations limit the voltage you can bury or expose to safety levels (typically 35-48 V AC or less). and with the prevalence of LED lighting today there are lots of good power supply options in the 12 V and 24 V DC range. 

I'd suggest a waterproof 24 V DC exterior power supply may be a good starting point for your project. I'm not suggesting this particular unit, but it will give you an idea what to search for, Uxcell waterproof LED lighting supply 1.

With a suitable 24 VDC power supply rated at 100 W or more (I'd recommend you use 150 W) you can run 5 torches in series (with a safety diode to lessen the likelihood you could blow any up with a reverse cable connection) and so have 6 cable runs to get your 30 units in total. Each torch now gets approximately 4.6 V which is right at the top of the range of our graph and shows a current per string of about 670 mA (less than 30 mA per LED, which is still within ratings).

If you want the torches to be dimmer you could run 6 torches in series per string (with 5 strings). This would result in approximately 3.8 V per torch and about 370 mA per string (about 16 mA per LED).
Note: You don't need to modify the torches at all, you simply connect 5 or 6 of them in series and they all have their own internal limiting resistor still in place. 

Even though the power supply is short circuit protected, I'd suggest you add a 5 A output fuse (you can get inline fuse units) on the 24 VDC side so if you get any shorts in the garden you are protected. I'd further add an inline 1-2 A fuse on each of the series of torch strings. 

So my suggested schematic would look like this:







simulate this circuit &ndash; Schematic created using CircuitLab

With a maximum current of about 4 A from the power supply and 0.66 A in each torch run you should be able to use any reasonable garden/exterior rated cable of at least 10 A capacity (typically 10-16 AWG equivalent wire). The voltage drop in any particular cable should be kept to the minimum, but is going to be dependent on how many runs you have and the cable size you use. This will obviously be the most expensive part of your project since 1000 ft of cable is rarely cheap.
A good place to start for resistance values is this chart.
If you use 10 AWG wire (2 mOhm/ft) for the major spine from the power supply and 16 AWG (4 mOhm/ft) for the torch runs it should be possible to minimize the voltage drop to less than 0.5 V end to end.