Each type of garden plant needs some sort of attention the end of the season. Summer vegetables should be picked clean and pulled up, and perennials often get cut back. Annual flowers such as cosmos and zinnias are also on the fall clean up list, and fortunately, dealing with them at the end of the season is a straightforward task.
Cut back or pull out old annual flowers at the end of the season since they won’t grow back next spring. Remove spent annuals from flower pots and save the soil to refresh for next year. The dead annual plants can be composted or thrown away.
Coming up are some tips to help you decide if you should remove the annuals from the garden or leave them behind to serve another purpose.
If you’re a podcast lover like me, check out this episode of my podcast, Organic Gardening For Beginners, to learn even more about the end of the flower season.
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What to do with annual flowers at the end of the season
You have a few options for dealing with your annuals at the end of the season, depending on what your agenda is for your garden. You can pull the plants up after they’re done blooming, or you can leave them in the garden through the winter and remove them in the spring.
If you’re looking for annuals that will bloom as long as possible into the fall, be sure to check out this post for some ideas: 11 Fall Flowers That Will Bloom Beyond A Frost (With Pictures).
Pull out plants after they’re done blooming in the fall
If you like to have everything straightened up and tidy by the fall, then pull up the old plants and compost them or toss the dead plants in the garbage. Since annuals will only grow and bloom in one season, leaving them in the ground will not result in new growth or blooms next spring.
To remove the annuals, cut the stems off at soil level, leaving the roots in the ground, or pull the plants out completely.
If you choose to leave the root ball in the ground then worms, soil bacteria and fungi, and time itself will break it down over the winter. You might find some roots in the spring, but they won’t stop new plants from establishing themselves and growing well.
Leaving the roots in the soil is a great way to practice one element of no-till gardening. When you avoid pulling roots and dirt out of the ground you leave the soil undisturbed and all the soil structure that has built up over the season remains. Soil structure is important for soil health, water retention, aeration, and more.
If you don’t want to leave the roots in the ground, that’s okay, too. After all, this is a small are we’re talking about, and pulling up the roots and dirt won’t create any damage to your garden.
Simply pull the plants out with a strong pull, or use a shovel to help pry them out if the plants resist. Shake off the excess dirt by banging the root ball against the ground, then toss the whole thing into the garbage or the compost pile.
Flowers can easily be composted along with other garden debris. Fresh leaves and stems are the “green,” nitrogen-heavy part of a compost pile, while the dead annuals and roots make up the carbon-heavy “brown” portion of the pile. For quicker decomposition, run over the plants with a lawnmower and dump the collection bag in the compost bin.
For a clear, easy-to-use explanation of how to compost, check out this video from vegetable gardener Huw Richards:
If you don’t have a compost pile but you do have a landscaping bin for municipal composting, then use that. Just make sure to remove any ties, stakes, or labels before you put the plant in the bin.
Let some annuals reseed themselves or feed the birds
If you don’t mind having old plants remain behind, then leave them to reseed themselves or provide food for the birds. Then pull the plants out in the spring and get on with your new garden.
There are some annuals that might come back the next year by reseeding themselves. It’s not the plant that comes back, but rather the seeds that the old flower drops before you pull it out of the garden. Letting some flowers reseed is a great way to have your favorite flowers on repeat in the garden without needing to replant them yourself.
Some annual flowers that are great at reseeding themselves are cosmos, calendulas, marigolds, and nasturtiums. In order to successfully self sow, the seeds have to be left on the plant to mature and dry out. When they’re ready, the seeds will drop to the ground below and wait for ideal conditions before they sprout.
You can even break off the seed head from the stem, take it to a different area in your yard or garden, and shake the seeds onto the ground there. That way you can try to get those flowers to sprout on their own in a different area where you need some color and beauty.
Any annual plants left in the garden at the end of the season are also wonderful food for birds and habitat for overwintering beneficial insects and pollinators. Birds love to perch on dried flower stalks and eat the seeds. Bees and other pollinators hibernate in hollow sticks and stalks, so leaving those on the plant provides shelter for these essential bugs.
Once spring returns and the plants have fully done their job in the garden, go ahead and cut or pull them out. They will break down very quickly in the compost after a winter exposed to the elements, resulting in a quick batch of fresh compost for the new season.
Potted annuals need to be cleaned up, too
Potted annuals get the same treatment as annuals grown in ground.
At the end of the season, clean up annual flowers grown in flower pots by pulling the plant out completely. Compost or thow away the old plants, and set aside the pots to replant next growing season.
The reason for pulling out the rootball along with the plant is that the roots will have a difficult time decomposing in the pot. When roots are left in behind in an in-ground or raised bed garden, worms and other soil organisms can easily reach the roots to break them down.
In a pot, the access points to the soil are only the small drainage holes. Worms and other organisms will have a much harder time getting into the pot to help with the decomposition process. Of course, the soil will eventually break down on its own, but it will take a much longer time.
If you want to reuse the soil or the pots anytime soon, it’s best to remove the roots at the same time as the plant.
when should i remove annuals?
You can remove annual plants from the garden after they’re done flowering for the season, after the first frost kills them, or in the spring. If you have the space and don’t mind the look, leaving dead annuals in the garden is a great way to offer up seed heads to any birds and other wildlife that will visit your garden during the winter and early spring.
If you wait until spring to take the old plants out, wait until the weather has warmed up for at least week. Over the winter, many insects have probably made their home in the dead foliage and stems and they need warm weather to emerge from hibernation.
If you pull out an old plant and throw it away during the chill of early spring, you might be throwing away a colony of beneficial insects that would otherwise help your garden.
For a fascinating read, check out this guide from Xerses, an organization focusing on “protecting the natural world through the conservation of invertibrates and their habitats.” In the guide you’ll learn all about what you can do to provide nesting and overwinter habitat for pillinators and beneficial insects in your garden.