Q: I want to save seeds from my Shasta daisy. Last year I waited for the seedhead to change color, but it never did. Does a Shasta daisy not have time to make ripe seeds here?
A: There might be years when the seeds did not ripen, but Shasta daisies bloom early enough that seeds usually have time to mature before frost. Probably your seeds were ripe without your knowing it.
There are some kinds of seeds in which ripeness is not indicated by a color change. Composites, or daisy-like flowers, belong to this group, and your Shasta daisy would be one of them. With these flowers the seeds are ripe when it is easy to pull off the seedhead. If you left the Shasta daisies in the flower bed over the winter, look in the area for seedlings this year. Some of the seeds should have fallen and germinated around the parent plant. They would survive winter in good health as long as you did not clean up too much and scrape the ground bare.
If you turned your dead plants into mulch, some of the seeds are likely to germinate where you spread the mulch. In my gardens, Shasta daisy seeds have started new plants in three places where I never planted them.
Many perennials hardy in this area are quite capable of reproducing themselves without human help. If seeds are allowed to ripen, they will fall and spend the winter in the flower bed. The next spring — or, for a few varieties, the spring after the next one — the seeds will start to grow. Their inner clock will tell them to start when the soil is moist and when both soil and air temperatures have risen enough. The gardener need not collect the seeds, start them in pots, and transplant them outdoors.
With Shasta daisies you want to be sure that you are saving seeds and not just dead flowers. There are an enormous number of Shasta daisy cultivars, and quite a few of them are sterile. They simply do not make seeds. This is particularly true of the double flowers. To get new plants of these sterile varieties, simply divide them, preferably in the spring.
Q: I saw some pink and white cosmos blooming, but they were only a foot tall instead of five feet, and the plants did not sprawl over a big area. How can I get my cosmos to look like that?
A: You want to buy seeds for one of the compact varieties. The standard species of cosmos, C. bipinnata, makes huge plants. A few of the cultivated varieties have been selectively bred to grow 12 to 18 inches tall and about the same width. One of the best and easiest to find is called ‘Sonata.’ As long as it has plenty of sun and fairly good soil, it is easy to grow. Its flowers are the same size as those on its giant relatives. Another short variety is called ‘Versailles.’
Like the big cosmos, ‘Sonata’ plants will keep on blooming until frost if the faded flowers are clipped off. If they are not deadheaded, cosmos will shift from making flowers to making seeds.
The red, orange, and yellow cosmos are a different species, which came from Central America instead of Mexico. They are shorter, with double flowers. They will not bloom all summer like C. bipinnatus.
Q: My vegetable garden is infested with that weed that has thick leaves and little yellow flowers and crawls around the ground. I think that it is called purslane. I sprayed it last year, and this year it is worse than ever. Can you tell me what spray to use? Or should we stop gardening next year, cover the area with black plastic, and start again in two years?
A: You are quite correct about the name; it is purslane. Unfortunately your possible ways to get rid of it will not work. There is no herbicide available to gardeners which will kill purslane, and covering the area for a year will not eradicate it, either. A truck gardener once told me that he thought it the only plant in the world which could grow under black plastic.
Are your plants forever doomed to be overrun by purslane? No, you can get rid of it, or almost all of it, within a year or two. The only ways to do so that I know of are to mow it to the ground or to pull it. Purslane is an annual, which makes it an easy weed to exterminate. Like any annual flower, it grows from seed every year. If you prevent it from making seeds, this year’s plants are the end of the line.
There are a couple of details about purslane which you need to know. Because it is a succulent, it stores a lot of water in its leaves, enough to develop and ripen seeds from flowers even after it has been pulled out of the ground. Enough to generate a new root system from stems left on top of the ground.
In other words, if you pull purslane plants, do not drop them on the soil. Collect them in a container. If you cut them to the ground with a weedeater, watch for new growth and cut any new shoots again.
When you see purslane flowering, you know that it is time to remove it from your garden, so that its flowers will not develop seeds. In August or September, though, purslane can make seeds without those yellow flowers. You will see only barely visible flower buds. They look like yellow-green circular leaves at the branch tips. They make seeds just as the early season flowers do. Do not leave those buds in the garden.
If no purslane produces seed in your garden this summer, most of your problem will be over. Every purslane plant produces thousands of seeds, so you want to remove every single plant that you can find. It can be hard to believe how quickly you can destroy its green carpet, but you can.
There will be seeds left in the soil from previous years; they will sprout next year. But every year purslane plants will grow only from those leftovers. Although you will probably never pull the last purslane plant, you will see only a few each summer.
Has everyone noticed how few grasshoppers there are this year? Contrary to last fall’s dire prediction of hordes which would eat up the landscape this summer, this year’s population is tiny. In my area, I am seeing perhaps one percent of last year’s numbers.
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