difficulty to grow: moderate, not too good in cold.
Perrenial or annual:there is a few types of alfalfa, annual i believe. Then there is non dormant, semi dormant, and dormant alfalfa. The more tropical you are you want the non dormant full perennial, the further north you go you want to get into the semi and dormant alfalfa. Which go dormant in the fall and winter.
invasive or not:possible, if you let it go to seed.
when to harvest:you could harvest sprouts( and eat them), wait till they are mid age or right when they flower for highest nutrients.
soil conditions: light, well drained deep soil, but ive seen people grow it in pots many times but you loose the benefits of alfalfas deep roots.
when to plant:spring-summer outdoors, all year indoors.
info:alfalfa is a great plant, one reason is its available everywhere, and its cheap, and it works awesome. Alfalfa is one of the more commonly known plants that are used as a fertilizer. You can get it at most animal feed stores for very cheap, its 12$ for 50lb bag here. Given how you use it that could last well over a year specially if you use it with your own homegrown fertilizer as well as along with your free compost and others. As some people know there is a secret ingredient in alfalfa, its Triacontanol, and from my notes ive collected we have this explanation. Triacontanol is a straight-chained alcohol that has growth stimulant properties... From notes "Triacontanol has had good results as a bating-agent, when added to soil and most of all: as a foliar spray. For a long time it was unknown what caused the growth-improving effect of triacontanol. The latest researches suggest that triacontanol directly activates the genes that control photosynthesis. These genes in turn activate the enzymes controlling the chemistry of photosynthesis." take into account the amount of N available at the same time and you get great growth and overall plant health. I like to use this along with nettles. Alfalfa is a great plant to grow, it's roots go deep, sometimes 20ft deep. This breaks up any hard spots and or hard layers, in the mean time they are fixing nitrogen into the soil with the help of microbes on the root. And when the roots die and decompose after you chop they create air pathways in the soil, highways for worms, and easy pathways for your next crops roots to get use of all the nice new aerated nitrogen rich soil. So when that is happening you will be either composting the top greens, drying some for use for months to come, or making liquid extract to use when the nitrogen fixed gets used up. I would suggest to always save some for drying, you can use the dried leaf as a soil amendment, compost tea, liquid extract, compost, mulch.
what to do with it:
----soil building: grow alfalfa in your soil( best to be in ground) you can apply a nitrogen fixing bacteria inoculant if you want, but i dont and it works fine, nature does her job. So now over the season on your soil, the bacteria and plants will fix nitrogen into the soil ( take it from the air, and put it in the soil) as well as shooting roots deep aerating your soil and making it lighter and not as compact. When the plants are beginning to flower you might want to let them flower for a little bit, as it will bring nativebees and wasps and beneficial insects such as hoverflies.
-----soil amendment: so now the growth of alfalfa is over, its going to go into making seed soon, now is the time you want to chop chop. If your going to make a soil amendment you will want to dry it first, try not to just lay it in the harsh sun and roast it. I like to leave it in the spotted shade/sun of under a tree. Im pretty sure you could also hang dry it upside down like a herb plant if you wanted. Just do what works best for you. Now that its dry, take a bucket or a trashcan. Put alfalfa in and smash with a 2x4 to almost a powder. Then take that and make sure its dry, then put in storage. To use just mix into the soil at about a tablespoon per gallon or less, for lighter feeding plants.
-----compost: after you first harvest, and the plants are fresh. This is the best time to make compost with alfalfa. Its still got all the juices inside the leaf. Get your pile layer some browns, top it with a couple inches alfalfa, and keep layering like that. And watch the heat rise! Apply the quick return compost activator to speed things up even more. And remember compost owns all!!! The best freee fert and alfalfa helps add to the goodness.
-----liquid extract:this is going to be your quick fix with alfalfa, you take all the nutrients ( well most to be technical) all the water soluble nutrients i should say. And we all know plants uptake water soluble nutes no problem, even without a microbe population, thats why we have hydroponics and soluble fertilizers. So you would do basically the same thing as nettles, yarrow and dandelion. Take a bucket, add alfalfa, let sit( the longer it sits and the more you add the stronger it will be you CAN burn plants with alfalfa so dont think you cant) strain add the wet stuff to the compost and watch the heat rise, dilute the liquid, dilute it more for the longer it has sat. Say 1 cup per gallon that sat a week or so, id dilute 1:10-1:20. But i dont measure.
caution: the longer it sits, the stronger the smell. It can get bad. But once applied and watered in its
------cover crop: this is the old school way, the way most people know alfalfa is used. Grow alfalfa, when it gets about a little over a foot tall. Mulch it into the soil( roto tiller works, but goes against the no till rules, but will still work your not going to kill all the microbes lol thats impossible) then cover with mulch or some finished compost. Let sit for a few months or over winter and then plant in spring.
----foliar spray: take some of the liquid extract, dilute a lot. Foliars work best when in very very very dilute amounts. So dilute sometimes you would think its pointless.
where to get it: of course this beats growing your own ferts, BUT......you can buy this at most all animal feed stores. I was recently passing by the animal feed store and checked it out, they it was a 50lb bag, and it cost 9$. Enough to last a long time. But this kind of defeats the purpose of growing your own ferts. But for those that cant it is an option.