Planting Annual Flowers

Getting flowers off to a good start

By: Sandy Feather 2007
Penn State Extension

Q. I planted some annuals in my front yard - mostly geraniums (Pelargonium spp.), nasturtium (Tropaeolum spp.), and dusty miller (Senecio cineraria) in the sun and impatiens (Impatiens spp.) where there is more shade. They looked great when I purchased them at the greenhouse. Now the impatiens and dusty miller are fine, but the geraniums and the nasturtiums look like they are drying up. I have been watering carefully, so I am at a loss to explain what happened to them. Do you have any ideas?

A. Since the other plants are doing well, I believe you are watering properly. It is likely that your geraniums and nasturtiums are suffering from heat stress and possibly sunburn because they were exposed to a full sun situation abruptly rather than given an opportunity to acclimate gradually. The impatiens are in the shade, so sun is not as much of an issue for them, and dusty miller's gray leaves are not as sensitive as those of the nasturtiums and geraniums. Our above average temperatures and unusually sunny weather have not been kind to tender transplants.

Establishing Annual Flowers

They have not had a chance to establish much of a root system, which makes it hard for them to absorb enough water to compensate for the hot, windy weather we have had lately. Rainy, cloudy days give new plants a chance to become more established, and we have had precious few of those since 2007's spring planting season arrived.


Watch the Young Plants on Sunny Days

Just as people can get sunburned or experience heat-related illness on those first sunny days in spring, plants can experience heat stress, and even have their leaves sunburn when taken from a protected greenhouse to a sunny flowerbed. Greenhouse glass reduces the sun's intensity, and plants in those structures are protected from the wind.

red salvia

And just as we are less likely to burn once our skin tans, plant tissue hardens and develops a thicker cuticle and is less likely to burn once it gets acclimated to the stronger sun intensity outdoors.

While you cannot put sunscreen on your plants, you can protect them by gradually exposing them to more sun every day over a seven to ten day period. This process is known as hardening off, and it can benefit the plants you purchase from greenhouses or those grown from seed indoors.

Transitioning New Plants to Flower Beds

Start by moving your plants to an area where they receive an hour or two of morning sun, then shade from the hot afternoon sun. Protection from wind is important, too. The wind will suck the moisture from tender leaves that are not hardened to life outside. The next day, leave them in the sun for three hours, the following day for four hours, etc., until they are out in the sun all day. Then you can plant them safely in their permanent spot for the summer.

blue salvia

Your plants may not look good right now, but most of them should recover and bloom normally for you. They will lose the badly sunburned leaves, but new leaves better adapted to the sun will replace those If possible, transplant seedlings on cloudy days or in the evening. If that is not possible, create tents of newspaper or cardboard to place over seedlings transplanted on a sunny, hot day if you know they have not been hardened off beforehand. Many greenhouses and garden centers do not have the luxury of hardening them off before sale. Oftentimes, they purchase plant material in to keep up with demand in the spring, and they do not keep it long enough to harden it off.


Outstanding annual flowers

Annual flower ratings

Storing seeds from your garden


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