Every gardener needs to know the difference between Annuals and Perennials. So what is an annual? What is a perennial?
The short answer is:
It's the lifespan of the plant that determines if it's an annual or a perennial plant.
As Webster’s dictionary remind us, annuals live out their entire lives in about one year. Perennials, in comparison, are plants with a lifespan of two or more years.
There! That was simple wasn't it?
Of course how to use annuals and perennials in your garden is a much more nuanced question. So now for the long answer...
You probably have lots of ideas for every inch of your garden. Should you plant annuals or perennials? Okay here is the good news...
Both annuals and perennials can be suitable for all types of climate, light, drainage, and soil. You just need to choose the correct variety for your garden and region. So what does determine which is best for your space? First let's cover the different survival strategies these two groups of plants use.
Both annuals and perennials can be suitable for all types of climate, light, drainage, and soil. You just need to choose the correct variety for your garden and region.
Also, there are very expensive and very cheap ways to grow both annuals and perennials. Cost is not really a factor at the home garden scale.
So what does determine which is best for your space? First let's cover the different survival strategies these two groups of plants use.
Annuals save nothing for future years. They sprout, reproduce, and die over the course of one growing season. Annuals grow quickly, and put as much energy as they can into producing as many seeds as possible. Seeds come from flowers, which means more flowers for you!
Perennials reproduce as well, but don't put their whole effort into reproduction. They save some materials and energy for themselves to live another year. And perennials grow at a more measured pace. Perennials produce fewer offspring. But their offspring have more resources to begin their own lives with. Perennials often create clones of themselves from offshoots of their root system.
Annuals stubbornly insist on doing all they can to create seeds. They are going to die after 1 year so flowering is their only chance to survive through their offspring. If you pinch off a flower, the plant will sense the absence of that flower and start producing more flowers. That's why deadheading works so well with annuals. You can pinch off wilted flowers before they go to seed and the plant will try to grow another flower. This can give you a blooming time for a longer part of the growing season.
Perennials are not as self-sacrificing. They make an effort with flowers but they rarely keep blooming if you destroy those flowers.
Annuals fling themselves wholeheartedly into reproduction. Their own life support is not as developed as perennials. If you are on vacation perennials will dip into the reserves they have stored in their roots to survive. Annuals might not still be alive when you get home. This is especially true if you start your annuals from seed. When they are in the sprout phase, plants are extremely vulnerable to dehydration. So are you away from home a lot? It's something to consider.
Your own personality can guide your choices. With an annual flower garden, you can start something completely new every year. You can try hundreds of different varieties and combinations with little consequence.
If you like the idea of having a long relationship with plants over the years, perennials are a good fit. And here's my favorite thing about perennials... All the perennials around my home were divisions from other friends’ gardens. When I walk around my property I can think of these wonderful people in my life and how happy I am to know them.
Beautiful perennials will come back every year. They will become part of the memories you have of a particular place. When old friends return each year the sight of those flowers can give great pleasure.
The amount of work you are willing to put into a plant variety is always something to think about. It does not dictate whether you should go with annuals or perennials. You do need to plant Annuals again every year, but perennials may also need care to help them survive the winter. There are varieties of Annuals and perennials for lazy and active gardeners!
Gardeners each have their own tolerance to "plants in the wrong place". Remember annuals vs perennials have different lifespans. This complicates matters when it comes to weeds
Perennials can serve as a double edged sword when it comes to weeds. A dense group of perennials can be an attractive, non toxic barrier. They can prevent grasses and other spreading weeds from penetrating into a space. You can plant perennials under a tree, along a fence line, or around a border to form a barrier to weeds. You can even use a barrier of perennials to discourage unwanted insects from your garden.
Yet, if a weed does establish itself in a perennial bed, it can be difficult to dig out. You might end up damaging your plant in the process. It helps to know your local weeds. Fast growing annuals or dense growing perennials are your two options. Try to figure out which type will compete better than your local weeds.
In contrast, if you plant a bed only of annuals you can replace the entire bed and can remove any weeds every year.
Perennials can also become weeds by dividing quickly. If this happens they can produce a mass of roots that is difficult to remove. These are what many garden experts call “thugs.” Read between the lines of nursery labels. Look out for terms like“quick spreader,” “strong grower,” or “fills in rapidly”. These phrases should trigger alarm bells! They might suggest the plant can take over your whole garden! Roots can even penetrate under brick walks and other features! These plants are best planted in a container with a physical barrier underneath it, or left alone.
Besides taking over your own garden some plants can lead to ecological problems. Patches of garden plants can spread and grow in fragile wild habitats. This can destroy the area for native plants and birds. Cuttings from perennials and windblown seeds from annuals can both be a risk. Research invasive plants through your local cooperative extension office to avoid this. While many nurseries know and are conscientious about this problem, some are not. If you see plants for sale that are harmful species discuss this with the management.
You can have your cake and eat it too!
While it is traditional, you don't need to plant annuals and perennials in separate beds. Feel free to experiment with combinations of both plants. It can be a trick to prevent mature perennials from shading out young, growing annuals. So make that a factor in your bed design.
Garden designers suggest starting plans with shape and color before delving into specifics. Challenge yourself to try at least one color/shape combination you don’t think you will enjoy. You might be pleasantly surprised! One thing designers agree on is: go for variety. Place tall with short. Place dark with light. This creates a much more interesting garden.
When you design your garden, remember that everything is going to get bigger. The first day your transplants are in your bed, they can look a bit sparse. But, your plants will be healthier if you leave them adequate space to grow. Don't pack them in too tight.
Also, think about the greatest height of the plants you select. Will they create undesirable shade? Will they end up bumping up against railings or other features of your home?
Perennial plants are often chosen not only for their flowers but their foliage. Foliage can be attractive not only in its shape but in its patterns and colors. Flower Gardening Made Easy ’s page on foliage perennials contains terrific photographic examples.
Mixing flowers and foliage gives you a chance for artistry.
You can try planting group of cosmos, which are tall, annual plants with feathery leaves. The surround the bed with perennial ferns that echo that shape.
If you prefer contrast, try this...
Mix the sky blue flowers of Nemophila with red-foliage border plants. The contrast can be quite dramatic!
There are perennial plants with beautiful flowers. It's not that annuals have beautiful flowers and perennials don't. One widely planted and loved example is the perennial larkspur.
Larkspurs are very tall flowering plants that come in a range of colors. You'll find them in colors from pale pink to iridescent blues and purples. Larkspurs produce extremely large flowering heads with many blooms. You might start a fight between flower lovers if you ask if larkspurs are superior to peonies. It's a hotly debated topic!
Other examples of showy perennials include bleeding hearts and iris. My personal favorite is the siberian iris. Also you get all shapes and sizes of lily, including tiger lilies.
It is difficult to know where to start when recommending annual flowering plants. There are so many! I can never resist trying a little bit of everything. But if you must narrow it down, start with growing conditions and then move on to shape and color. If you do not want to stake plants, pay attention to how tall they grow. Plants that are too tall will fall over unstaked.
I have already mentioned baby blue eyes, but it is one of my favorites because of its sky blue color. I have found cosmos and calendula to be extremely easy to grow from seed, and enjoy their bright colors. Calendula has the added benefit of being edible and high in Vitamin E. Snapdragons are another beautiful choice, but I would recommend starts instead of seeds.
One more variety I would like to highlight is white alyssum. The honey-sweet smell will waft across your property. I plant it near my parking space so that the smell will welcome me home. Colored Alyssum is sometimes available at nurseries but they don't smell as sweet.
Gardeners often like to nurture local wildlife with their choices. You can choose flower varieties that will be hospitable to migrating butterflies. The Butterfly Association has a wealth of information to get you started.
Whether you choose annuals, perennials, or a mixture of both, nutrition is important. Flowering plants with more nutrients will combat weeds and pests better. But take note, fertilizers that are extremely high in nitrogen may not give you what you are looking for. You may end up with big vegetative growth, or green parts, and not as many flowers. Special fertilizers such as Morbloom contain nutrients balanced specifically towards producing more flowers. Compost is also typically well balanced.
Your garden is yours. Your first worry should be whether a particular flower variety will bring you joy. On whether you should grow annuals or perennials, the answer is likely to be… Probably both! Grow whatever makes you happy! And enjoy!
What do you think? Are you an annual gardener? Or do you love your perennials? Let us know in the comments!
Allison Sayer has a keen interest in homesteading, living with the land, and gardening. She has a degree in biology and brings her knowledge of chemical reactions and plant physiology to AskGardens.com. Tulip the dog helps too but Allison does most of the writing ))