The question “What is an Annual Plant?” comes up quite frequently mainly in gardening lessons and workshops, but at design meetings too. The confusion is understandable in those with little gardening experience.
Now you may be thinking the answer is elementary. But for those who are feeling a dash confused at why they saw their annual summer bedding plants also sold as small perennials an explanation could be useful. As we may know to our cost, plants and gardening are not always as simple as they first appear!
What is an Annual Plant?
The two key points that help define annuals are that they: –
- can only be propagated by seed
- grow, flower, possibly produce edible crop and seed, then die – all within the space of one growing season, sometimes referred to as one year
Also note that
- some annuals can be sown as seed in the autumn prior to the spring and summer in which they’ll flower. For example, sweet peas are often sown in autumn to produce earlier flowers.
- both edible plants and ornamentals can be annuals
Gardeners, growers and garden centres often refer to plants as being annual when they are treated as such in the garden or allotment. However, not all plants colloquially called annual are actually annual in their growth habit. They may be ephemeral, biennials or tender perennials. Let’s explore definitions for those types of plants.
Ephemeral plants
Unlike annuals, ephemerals produce many generations of plants during the course of one growing season. Many ‘annual’ weeds are actually ephemeral plants, for example, common groundsel, Senecio vulgaris. It’s seen here at a Gardening Lesson, where we’re checking the soil pH.
Being able to produce multiple generations in short time is a great survival technique. Although as gardeners we may be less enthusiastic at their prolific tendencies!
Biennial plants
Biennials, sometimes written as bi-ennials, may also be mistaken for annuals, especially when the plants are used in bedding displays. But as you may have guessed from their name, these plants have a two year life cycle.
In their first year they develop a basal clump of foliage and a tap root. This tap root is a storage organ which provides energy for the flowers or crop produced in the second year. Also in the second year, the plant sets seed, ready to begin the cycle again.
Humans have made use of this storage ability of certain biennials and developed useful edible crops. For example, root crops such as carrots are grown as annual vegetables, as we eat the tap root which the plant produces in year one.
Tender Annuals
A phrase sometimes used in seed catalogues. Generally speaking, plants referred to as tender annuals are actually tender perennials.
These are perennial plants that cannot withstand the cold, wet winters of the Northern hemisphere as they originate from warmer climes. They include many popular plants used as summer bedding. For example, Pelargoniums, aka pot geraniums, brighten up window sills and borders in summer but can be overwintered in frost free sheds and greenhouses to flower year after year.
Types of Annual Plant
The explanation for what is an annual plant continues with looking at their ability to withstand low or frosty temperatures. In ‘common parlance’, we’re referring to the plant, but botanically frost hardiness can also refer to the seeds. Which may explain why we’ve all had a no-show with some early sown seeds!
Hardy Annual
These seeds can be sown directly outside. This could be in a seed bed for later transplanting, or in the flower border or vegetable patch where the plant is to grow. Hardy annuals are frost hardy, so the seeds can be sown in early spring, as soon as the soil is workable. Or indeed, sown the autumn before to generate an earlier crop or flower. Some may need frost protection but some won’t.
Half-hardy Annual
When sown earlier in the year, these seeds need to be sown under protection, ie in a greenhouse or cold frame, or on a windowsill. Second sowings later in the season can be made directly outside once the frosts are finished.
Many of the plants we call half-hardy annuals originally come from warmer climates, or those with a longer outdoor growing season. Interestingly, a considerable number of these seeds will tolerate temperatures down to -5 degrees.
Tender Annual
See tender perennial! Despite the confusing description many of these are useful garden plants. For example, we grow tomatoes as tender annuals when they are tender perennial plants
Bedding Plants
These may be any of the above – and even hardy perennial plants such as Coleus and Begonia. See blog links below for more.
Why do we Grow Annual Plants?
On first glance it seems like a lot of work to grow annuals when you could just plant shrubs and be done. However, there’s a lot of border preparation needed for larger perennial plants as they stay in those positions in that soil for years, potentially tens of years, so it needs to be got right in the beginning. However annual plants, although I would always recommend some soil prep, have different needs. Because they’re in the ground for a comparatively short time, 3 – 6 months, they can survive with plenty of liquid feeding. What other benefits are there?
Annual flowers can be very useful in the garden. For example they –
- Can quickly fill up flower borders whilst perennial planting establishes
- Make a floral display you can change every year
- Wild flowers thrive on a poor soil so could be a good stop-gap measure while you decide what to do with a new garden
- Many annuals self-seed easily, so you may only have to buy a packet once
- Annual flowers can be easy maintenance, especially hardy annuals
- If you’re renting a property, it’s a cheap way to have flowers in the garden
- Are great for a mini cutting garden to give you floral displays in the house
And not forgetting the annual plants which we can eat, vegetables, fruit and herbs. Of course they have an obvious, culinary use, but they can also be decorative – think potager, a pretty kitchen garden. These will require a bit more planning than scattering seeds on soil, but check out other Plews blogs for the ‘how to grow’ both annual and perennial edible plants.
Hardy Annual Flowers
- Love-in-a-mist, Nigella damascena
- Pot Marigold, Calendula officinalis
- Shirley Poppy, Papaver rhoeas
- Sunflower, Helianthus annuus
- Sweet pea, Lathyrus odoratus
Half-hardy Annual Flowers
- Black-eye Susan, Rudbeckia hirta
- Cosmos
- Nasturtium, Tropaeolum majus
- Petunia
- Marigold, Tagetes
Annual Edible Plants
But there’s more to annual plants than just a pretty flower or decorative seedhead. Cereal crops such as oats and wheat are annual, although you’re not likely to grow these in most gardens! It is often trickier to work out whether a vegetable is an annual or a tender perennial, and to be honest, its not critical except in knowing whether you sow the seed under cover or straight outside.
But it is worth remembering that some of the annual flowering plants have edible parts. Calendula petals for example.
Veggies
- Cucumber Cucumis sativus
- Squash, pumpkin, Cucurbita
- Sweetcorn, Zea mays
Herbs
- Basil, Basilicum ocimum
- Dill, Anethum graveolens
- Summer Savory, Satureja hortensis
Annual Weeds
Easier to deal with than ephemerals and perennials, but, one feels, in the minority. But then when are weeds helpful? Although, some are edible and others can be turned in to compost…check out the ‘Weeds’ category for more!
- Cleavers, Gallium aparine
- Wall speedwell, Veronica arvensis
- Petty spurge, Euphorbia peplus
And finally…have I helped resolve the “What is an Annual Plant?” conundrum?
To a certain degree, it may not matter to you whether the plant in question is an annual, biennial or tender perennial if it fulfils the purpose that you’re growing it for. But it may explain why you found carrots on the allotment a couple of years after they ran to seed…
For more on gardening with annuals, check ou the blogs below and do get in touch for an easy maintenance planting design that’s filled to the brim from year one with annual plants and perennials.
Or why not ask about our bespoke Gardening Lessons, where your classroom is actually your own garden? You could learn how to grow an orchard of citrus fruits in your conservatory. We can help with both gardening basics and more ‘expert tasks’, carry out worm and other experiments and for example, also show you how to plan a vegetable plot. Have a read through this pdf download for info. And if you prefer company, there are small group Gardening Workshops to come to.
For further gardening advice and inspiration, check out Plews Potting Shed blogs, including the selection below Plus we have a monthly Tipsheet You could come and find us on Instagram Pinterest and Facebook too.
Feeling nosey? You can have a peek at the progress of my garden renovation, Spitfires and Slow Worms, on Instagram and Facebook
You’ll get to see it in person if you come to the Plews Gardening Workshops Although later dates and topics still need to be finalised, there are current ones on Eventbrite for you to book into. Follow for updates on topics and dates on Instagram, Eventbrite, Facebook
Related Gardening articles you may enjoy from our Award Winning Blog
9 Blue Hardy Annual Flowers for Bees
10 Hardy Annual Flowers to Grow from Seed
9 Edible Annual Flowers to Grow in Your Garden
Growing Calendula officinalis, Marigold
How Many Types of Basil are there?
Sunflowers and the Summer Solstice
Gardening Tips and Ideas
How to use the Three Sisters Cultivation Method
Planting ideas for Summer Bedding
Summer Bedding Plants – Questions and Answers
