I bought those same strips, and thought the same thing.
They're less than 2 weeks old, and telling me my PH is under 5.6.
If you want to trust it, then your water is WAY too hard. (unless you have cichlids, in which case I doubt you'd have plants.)
Also, maybe the swords were grown emersed or need more time to settle into your tank? If your PH or other parameter is drastically different from what they were in, many plants take a long time to adjust. (My java fern took two months before it stopped dying and grew at all.
If your aquarium is stocked properly, the one thing I've learned here is there's no need for CO2.
You have to learn about the "holy trinity" of plants, and get the lighting, ferts, and CO2 in perfect harmony.
BTW, the wpg rule was accurate when there was only one kind of flourescent tube.
(no CFL's). Since then, it has gone out the window. I think thats why now people with .3 WPG etc, have flourishing plants-
their .3 watts puts out as many lumens as an antique bulb puts out per-watt.
Good luck with your plants...
Also, whats your nitrite and nitrate according to those strips? (nitrate and ammonia are ferts for plants. If nitrite is over zero, then you have some ammonia derivitive in the tank (really a bad thing for fish, but good for plants.)
Also for root ferts they were reccomending fert sticks in the substrate. Liquid ferts, even injected into the substrate, will just diffuse into the tank.
(If your use something like flourite in the substrate, you won't need root sticks I believe.)