Plants need approximately the same wavebands of light that we humans see in; from violet to deep red, and on into the non-visible near infra-red (380 to 720ish nanometres - nm).
Normal incandescent bulbs deliver much of this, although special bulbs for plant growth are better - different spectra affect different aspects of plan growth, e.g. blue light can affect stem growth.
LEDs by contrast only emit light at very narrow peaks, and normal plant growth often needs a wider spectrum. At a push plants can get by on red LEDs emitting at 690nm with some supplementary light in the blue around 450nm, which can be supplied by some white LEDs. Many white LEDs emit in the approx. range around 450 to 550nm, which will not be enough alone to enable plant growth.
Check the image: the green lines are where you want your plant to be, so you can see that by relying only on white LEDs you won't be growing good berries. Supplementing with a few red LEDs (sorry I don't know how many you'd need, but look at the paper "Design and fabrication of adjustable red-green-blue LED light arrays for plant research" for information), and it will help a bit.