Winter in the grassland is not a time of waiting. This is when the year is actively formed. To collect the water you will need in the spring, you need to start now. First, you need a rock, then you need to place it at the right angle. Then you can plant stuff on its southern and western faces. That’s it!
Your first option is to make a small glacier by installing a vertical face to catch the winter sun directly as it comes in nearly flat from the southwest in the afternoon, capped with a sloping face angle away from it. As you can see from the example above, the warmth of the sun on the vertical face will slowly melt the snow that catches above. It won’t melt all at once, but little by little it will trickle down the stone, reaching the soil shortly before sunset, when the sun’s power to evaporate it away is fading and it has the best chance of reaching the soil or lingering long enough to feed lichens. The image below shows a second option.
In this case, a slope gouged in linked channels, with one face of each cut directed towards the afternoon sun will create a stream channel that can melt enough snow, slowly, to create a winter wetland at its base, effectively concentrating the water of a large area into a small one before the air can take it away again, as it does in the grasslands. In contrast, a spring flood would just flow away. Now’s the time to plan for spring! That’s because it is spring.
You can produce usable nitrogen from lichens, if you plant shady thickets uphill of where you need the nitrogen. The lichens will produce it on warm days (and there are many) all winter. A big spring melt will wash it to the lower edge of the thicket, just like the big boulder did above. Of course, the damp on your boulder should produce lichens on all its wet faces, which can then work like a thicket. That’s the rule: grasslands include fantastical glacial environments. Some of the glaciers aren’t even made of ice, yet do what glaciers do. Look what happens if you do it the other way around, using clay to stop the flow from a wetland, so you can plant grapes.
You get muck.
Only the continual application of herbicides will prevent that from becoming a wetland in the end. The Earth is not to be messed with. Imagine if those grapes had been planted, each with a stone instead of a pumped water system, and this water had been invited into the soil instead of repelled and eventually lost to the dry air. Now’s the time to start planning these technologies, for when we need them desperately. For guidance in our planning, we need look no farther than Big Sage. Here you can see dark, dead old sagebrush wood absorbing water and feeding the plants below a south-facing cut through a crop of lichens. If this were a currant bush, we could have a crop of currants for every crop of grapes. The currant, in turn, will need a rock to water it.
We can do this, but we should start now. It will take ten years for the watering system to mature. There’s no time to waste, only water to lose.