I'm trying to grow the following indoors:
Lambs lettuce
Purple Coneflower
Thyme
Dill
Bergamot
I'm having a hard time getting things to grow with fertilized soil and sunlight by windows, I'm wondering if any type of LED would help or am I missing something else all together?
If you have limited light this time of the year and want to add additional light to help your seedlings to be more success you can add grow lights. There are many types grow lights on the market. Unfortunately many of the LED lights have claims that are not backed up. The ads often use language to bring attentions to certain specification that their light offers. All to often these specifications have nothing to do with if it is a good light for your plants.
If you are looking for some good supplemental light you can buy a fluorescent grow light. These have been on the market for many years. They are simple. The are often the same shape and length of two plant flats. If you are using flats it is easy to have them fit under one of these lights. The are the micro fluorescent that are the size of one flat if you only have a few plants. That is six 6 packs, 32 2" or 18 4" pots. These are reliable lights for starting seeds.
If you want to save money on energy you can go with LED. If you want LED you want to make sure you buy a light that is Full Spectrum White Light. Avoid any coloured lights, even if they call them Full Spectrum. If you are just starting some seedlings a 50-100Watts should be enough.
You can buy them fairly inexpensive if you only want to shine light on a few plants. The larger the unit the more the price. If you are only using them for a short period of time, like just in the spring to get some seeds going then your cost will be more expensive overall compared to fluorescent. If you want to grow the plant from seedling to harvest under a light you will have to pay more for the unit, but you will save more money in the long run with LED.
It's the temperatures and light intensity as well as duration of light that need to be monitored.
Remember seeds are looking for moisture and warmth some look for light they don't need fertiliser until after the first true leaves appear usually after at least a week or 2 after germination
Don't use tap water in London it's too hard for most plants And they add chloramin(made from pee) which doesn't evaporate and will buildup in the soil leading to future problems that will be misdiagnosed on this site.
I only use bottled water that is at a PH level of 6.2 and 70 parts per million in the water. I started using a TDS meter to measure the parts per million And a PH meter but not ant more as bottles water is quite reliable when it comes to the ph and ppm I only fertilise the plants rarely to give the soil microbes a chance to establish them selves.
I grow thyme, lavender, strawberries, mint, cilantro, parsley, basil, spring onions, garlic ....
All indoors inside window box with the aid of an LED system that is dimmed down to minimum at 46w !
Notice how the strawberries and some of the mints prefer the sunlight over the LED radiation I think it's due to the intensity I will experiment when the plants are bigger
