5 Ways To Keep Summer Annuals Beautiful

5 Ways To Keep Summer Annuals Beautiful

July 5, 2021 | C.L. Fornari |

If you’ve planted annuals in your gardens or containers, know that there are specific ways to keep them beautiful and flowering for the rest of the summer. Here are 5 tips for making sure your annuals continue to perform, and what to do if they start to fade or die.

1. Keep the watering consistent and the soil evenly moist. If your garden bed, pots or boxes dry out in between watering sessions, the flowers will brown faster and the plants might even die. Hand water containers, but use a sprinkler or soaker hoses for gardens as hand-watering flower beds is never enough. When watering pots and boxes, fill them with water well, first making sure that the sun-heated water has run out of the hose before you apply it to the plants. (Sun heated water can kill your plants or cause significant damage to flowers and leaves.) After you’ve watered all your containers once, go back and do it again. This ensures that the entire rootball in a pot or box is evenly and well watered.

If your town has specific guidelines for how and when to water, of course you will need to follow those. But in general, water gardens deeply less often. Put a rain gauge in the area and see how long your sprinkler or irrigation takes to fill the gauge at least to 3/4 inch. Note that a carton, can, pail or other container does not measure inches of rain; only a calibrated rain gauge will accurately measure rainfall. Water your flower beds for as long as it takes to deliver 3/4 of an inch every five to seven days, depending on the temperatures. When plants are watered deeply they grow deep root systems that can last several days between irrigation sessions.

Begonias can get crown rot if the soil is kept too wet. Water containers with begonias well, but feel the soil and only water again if it is dry. Also, be sure your window boxes have drainage holes so that excess water is allowed to drip out.

2. Deadhead flowers on annuals that make seeds. Deadheading is the process of clipping off the spent flowers and the developing seeds just underneath them. Since a plant’s mission is to create seeds for the future, if a plant has produced seeds it will frequently stop flowering. Common annuals that flower best when deadheaded include zinnias, ageratum, dahlias, marigolds, annual daisies (Argyranthemum), salvias, cosmos, zonal geraniums (Pelargoniums) and regular petunias. (The Superpetunias and Wave petunias do not need deadheading but do benefit from pruning – more about that below.) Scissors are useful for deadheading fine-stemmed annuals such as cosmos, but pruners are good for thicker-stemmed plants such as dahlias.

The red line under the petunia flower show where to cut to successfully deadhead this plant. Simply pulling off the wilted flowers doesn’t get rid of the developing seeds on petunias – you need to clip the stem below where the seeds are forming.
Some annuals only flower early in the summer. Batchelor buttons, annual poppies and Cape daisies (Osteospermum) are a few examples. When these plants stop flowering, immediately deadhead them or clip them down by half. Occasionally they may make more flowers later in the cooler, fall weather. The annuals in this photo that will flower more when deadheaded are the cosmos and dahlias. The perennials such as the white daisies, may not produce additional flowers when cut back but the garden will look better for it.

3. Prune the long stems regularly. Some annuals, such as the Wave petunias, Superpetunias and Scaevola produce flowers on the end of long, vine-like stems. In order to keep these more full, bushy and flower-covered, prune three stems back by half every week, starting right now. Yes, you’ll be cutting off some flowers (put them in a vase indoors) but you’ll also be stimulating new growth further back on the stems. If you don’t do this, you’ll end up with long, empty, green stems with flowers only at the end.

This is a great example of pink petunias that have NOT been pruned back a few stems every week. See how most of the flowers are at the end of the stems and there is too much green? Had three stems been cut in half every week, that (and fertilizer…read on…) would have promoted twice as much growth and more flowers. The geraniums above the petunias also benefit from removing the stems of old, dead flowers. When a flower on an annual geranium plant fades, clip off the stem stem inside of the plant so it doesn’t show.

4. Annuals need fertilizer. Since annuals flower on new growth, it’s important to stimulate that throughout the summer. You can either apply a time-release fertilizer such as Osmocote or Shake N’ Feed, or use a liquid. If you’re feeding your annuals with a liquid synthetic fertilizer, make sure you’ve watered the plants well and they’ve had some time to hydrate before fertilizing. Never fertilize a thirsty plant.

This annual garden is fertilized by applying equal parts Shake n’ Feed and Plant-tone to the surface of the soil before the plants are placed in the soil. The time-release fertilizer stimulates the growth of the plants into early August, and the organic Plant-tone feeds from early August on. If you are applying a liquid, synthetic fertilizer to flower beds, don’t mix it too strong, be sure the plants are well watered first, and avoid splashing the fertilizer on the leaves. (Note: you can add time-release fertilizers to containers and flower beds even in July.)

5. Know when it’s time to say goodbye. Whether they are in a pot, box, hanging basket or in the ground, if your annuals are no longer beautiful, it’s time to say goodbye. If there’s one annual in a container that looks bad, you might be able to just cut it out and let the other plants grow on without it. Or, you can also dig out the failed plant and replace it with a new annual. In gardens you can add annuals all summer, so don’t be discouraged by those that might have dried up or been eaten by critters. Plant something new! On Cape Cod, annuals will flower into October, so even if you replace a few flowering plants in July, they will make you smile for at least three more months.

The verbena in this pot wasn’t deadheaded, and it dried out a few times. Needless to say, the entire pot is no longer attractive. Time to empty it into the compost, fill the container with new soil, and put something that’s fresh and lovely into the pot. Yes, fresh soil will help – if you plant in the same potting mix that this verbena grew in, the new plant won’t be able to grow its roots quickly or deeply, so the new plants won’t get up and flowering as fast.
With the right combination of plants, good soil, fertilizer, deep watering and deadheading your annual flowers will be making you happy all summer and into the fall. And here’s a bonus hint: The more you cut the orange zinnias, peach dahlias, and purple ageratum and tall purple Verbena in this photo, the more flowers they will produce! Bouquets for everyone!
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