Gardeners use the term “volunteer” to describe the seedling of a desirable plant that appears in a garden without having been planted. They can be the offspring of trees and shrubs, but they’re most often the result of seeds dropped by annuals or perennials grown previously.
One of the tricks for using volunteers in your garden is the ability to distinguish the seedlings or young plants of desirable ornamentals from unwanted weeds. Some books on growing plants from seeds include pictures of what the seedlings look like. You can also become familiar with the seedling stage of many annuals and perennials by growing them from seed yourself and observing them closely.
Keep in mind that any plant growing where it is unwanted can be considered a weed. Even volunteers of the colorful, fragrant four o’clock may be weeds if they grow in the middle of your rose garden or if there are too many. Live oak seedlings come up all the time, but you don’t want them growing in your flower beds. The art of using volunteers is not simply to allow every volunteer that pops up to grow. You must take into account the space needed by other plants growing in the area, flower colors, plant heights and the overall design of the garden.
On the other hand, volunteers can offer unimagined combinations. Using volunteers can add an element of surprise and a delightful, informal look to the garden. Sometimes these chance combinations turn out more beautiful than anything you had planned. In my garden, the chance appearance of Kingwood Gold Jewels of Opar (Talinum paniculatum Kingwood Gold), with its large, oval, chartreuse leaves, among a planting of yellow columbines and blue forget-me-nots created a far more beautiful combination than I had originally planned.
If you want to encourage volunteers in your garden, you must allow seeds to form and mature on the plants you want to self-seed. Keep old flowers picked off early in the season to keep your plants attractive and encourage more flowers. But towards the end of the season, allow the flowers to go to seed and let the seed mature. Then, either harvest the seeds and scatter them around or simply let nature take its course and allow them to fall where they will.
Two other factors will affect the number of volunteers you see in your garden. Efforts to control weeds will also prevent volunteer seeds from germinating – using mulches and herbicides can limit or eliminate volunteers. Although I rarely use herbicides in my garden beds, I do mulch. Even so, I still see determined volunteers coming up here and there every year.
Not all garden plants produce viable seed. And of those that do, many just don’t come up well under garden conditions. But many others are very adept at producing new generations in the garden. Even if you put a plant in your garden that reliably self-seeds, things still may not work out. Sometimes a plant that self-seeds with abandon in one gardener’s beds self-seeds little or not at all in another garden under similar conditions. Such is life.
Garden volunteers come up in the most unexpected places. Cracks in paving, flower pots and along the edges of beds are some typical spots. And it’s often necessary to either pull them out or transplant them to a more desirable location. If moved when very young, most volunteers can be transplanted with great success. You can even put them into small pots or cell packs filled with potting soil, grow them until they are larger, and then plant them into the garden where you want them to grow.
The following lists include some plants I have found to be reliable self-seeders in our area, But there are many more. The warm-season growers should be planted next spring. Plant the cool-season growers in October or November. Also, check with your gardening friends. They may have extras of plants that self-seed and would be happy to share them with you.
Abelmoschus, amaranthus, ornamental peppers, periwinkle, celosia, cleome, cosmos, balsam, marigolds, impatiens, salvia coccinea, purslane, torenia, melampodium, rudbeckia, Mexican heather, jewels of Opar, four o’clock, asparagus ferns, knot weed, cypress vine, moonflower vine, cardinal vine, true ferns, basil, chocolate plant, garlic chives, perilla, ruellia, dahlberg daisy.
Larkspur, sweet alyssum, nasturtium, cornflower (bachelor buttons), poppy, johnny-jump-up, dill, borage, coriander, parsley, viola, annual phlox, sweet pea.
Dan Gill is a horticulturist with the LSU AgCenter. He can be reached at DGill@agcenter.lsu.edu