What NOT to do in late summer in the garden
Usually, I am waxing on about what to do in the garden, but this week, it is the opposite. I am going to tell you what not to do right now. Because doing some things right now actually can harm your plants for next year.
Are there are garden activities that we need to keep doing right now? Absolutely. Draw your attention to those annual flowers and vegetables. They only get one growing season to shine. And they continue to need care ‘til killing frost.
First and foremost, please, don’t follow the recent years trend of “just ripping it out to have it done with.” I see so many wonderfully producing vegetable gardens, and annual gardens obsessively ripped out just to cross it off the gardener’s list. Even if it was barely August. This year in particular. Our monarchs and other pollinators need you. So do your neighbors and food pantries.
Mother Nature has put us on the fast track horticulturally in 2024 by turning up the thermostat as far back as February. All of our plants bloomed three weeks to a month ahead, and for late-season insects, this can spell disaster. The goldenrod is already in full bloom, with the asters not far behind. What is left?
Our little state insect, the monarch, is in trouble already. Barely any spotted this year throughout the East; now, they are just starting to get the migration feeling. And flying those 3,000 miles, you get a little hungry. Monarchs relied on those late bloomers like goldenrod and asters — that used to bloom into late September, sometimes even October. But not this year. Your annual flowers are their lifeline.
Don’t clean things up just to have it done. Those monarchs and other pollinators need that nectar. Fortunately, annuals are pumping out blooms constantly — if only you continue to give them a little help. But are your petunias looking a little puny? Have your zinnias lost their zip?
There is still time to get those annuals back in shape so there is something for our insects to feed on. And the way the weather has been, they may still be blooming at Halloween. Continue to deadhead (remove spent blossoms), so the plants will continue to produce new buds and blossoms. Continue to water and fertilize those annuals to keep them going and growing — and most of all — producing nectar and pollen.
But when it comes to anything perennial, this is not the time to fertilize. Actually, you should not fertilize perennials after June 30, especially the woody ones — trees, shrubs and roses.
It is important to remember what fertilizer is: a stimulus to grow. When applied to plants, once the fertilizer migrates to the elevator circulatory system within the plant, it is “go time.” Not, “OK, I have a sandwich that I am not hungry for now but might eat later.” Plants do not have that luxury. Feed it, they have to grow, regardless of what Mother Nature has tuned up for us.
If you fertilize in late spring, and it takes the fertilizer a few weeks to get absorbed into the plants, they have to grow, regardless if it is 115 degrees in the shade in June. Put away the fertilizer ‘til late November, more on that in a bit.
The reality of woody plants is they really have two seasons during the growing season. The first starts when the soil and air temperatures warm in combination with the increase in daylight hours. This is when perennials flush growth. This continues till the end of June.
But there is a second part to woody plant growth that is essential. And this is where fertilizing too late into the growing season can waste your plant’s energy budget for next year. The second process of summer woody plants is hardening off the newly grown wood, so it is prepared for whatever winter brings.
If we continue to fertilize woodies after June 30, particularly if the later summer cools and we have some rain, our plants will continue to flush new growth. I had this happen with some roses before I knew this. And late in summer, my summer fertilized roses put on 6 to 8 feet of new growth. How exited I was!
Until the next spring, when those long, green canes were black and dead, killed by winter temperatures. Were my roses fine? Yes, after I pruned off the wasted, late, dead growth. But I wasted the energy budget of those roses. If I had just stopped fertilizing, the natural hardening off of the wood would have held the purse strings tight; not wasting growth that would be killed, instead, saving it for next spring.
What you can fertilize now, besides the annuals, is your lawn. Fall fertilizer application is recommended around Labor Day. Our turfgrasses are cool-season and will perk up again once the temps start to decline.
The other gardening chore not to do now is pruning woody plants. Similar to fertilizer, pruning can stimulate growth, and we would have more late-season green wood. Even more importantly, many homeowners have called me mid-spring, distressed that their lilac isn’t blooming.
I asked when they pruned last, and sure enough, it was the previous fall. I had to deliver the bad news that they had cut off all the flower buds for spring. Any spring flowering shrub you have now has already set the buds for next year’s flowers.
Put those pruners away until winter.