Late summer is an important time in the perennial garden. It’s a time for the garden to prepare itself for the coming winter. The gardener can help this process along, though the help we can provide might seem counter-intuitive.
After the hot weather we’ve had, there’s a natural desire to try and use the cooler weather that seems to have finally arrived as an opportunity to “green up” and “flower up” the garden a bit – to pour on the water and see if we can get the garden really “cookin” again before winter. But for most perennials, this is exactly what they don’t need.
There are exceptions for sure, but in general, perennials need to be “hardening” themselves off for the winter now. They spent energy early in the season building themselves us, and most of them have spent energy throughout the summer flooding our gardens with blooms. Now comes the time when they need to pull their energy back into their root systems in preparation for the winter.
But if we pour water on the garden to try and “green it up”, we just confuse matters or worse. While we should still make sure the garden has sufficient water, we should be starting to cut that water back as the weather cools. That appears to be happening right now, with the highs this next week 10 or 15 degrees below what we had this last week.
For trees, it’s still OK to give them a good deep watering now and again if they’re young, but generally their system needs to go through the same process of hardening off, and reduced water helps them get there. We plant a lot of Honeylocust here along the Front Range, as they adapt so well to our climate and our soils. However, the Honeylocust can suffer tremendously from too much water late in the season. Unless you have a newly planted specimen, I generally recommend holding off on watering after September 1 for these guys. A hint on the Honeylocust is to look for “tip die-back” in the spring. If you notice that the tips of branches appear to have died over the winter, this is a sure sign of too much water in the fall and winter.
For lawns, (though I readily admit I’m not a lawn expert), it’s probably a good idea to reduce our watering schedule as well. I’ll cut my water in half starting this weekend in response to the cooler temperatures, and may cut it more than that once I see my water bill for last month…