On Tomten Farm we add various animal manures to the soil before we till. Our current favorite is llama manure which we obtain locally. Llamas' digestive systems actually break down weed seeds. When we're ready to plant we also toss in a handful of compost in each hole before setting in the young transplants. Just two of our favorite mail order suppliers.
Capricious weather is a given up here.
One of the ways we deal with that uncertainty is to start seedlings inside and let them get a head start before setting them out in the harsh reality of outdoor life. A seed is an amazing thing. Once you give it the right conditions it's hard to hold it back. We start ours in a mix of milled peat moss, vermiculite and perlite. Once the seeds have germinated the plants need lots of light or they begin to stretch toward the sun and become long, leggy and pale.