Gardening with Gary

Gardening Advice from an Expert

Zinnias

Remember the gardens of the '40s and '50s where the big attraction were those huge flowers of the Zinnia? I remember my Grandmothers' bouquets as big as a table (!) during the summer.

Now, there are old-style and wonderful new colored and bi-colored zinnias to choose from. They are so easy to start from seed, right in the garden bed.

You'll find a wide variety of seeds available in most any seed catalog, local nursery or garden center. Plant them outside when the soil and air temperature has warmed to about 60 degrees F.

You will have blooms in 2 to 3 months, with enough to cut and also leave in the beds for show. Remove when the flower dries to prevent seed from forming and encourage more blooming. Zinnias will also attract butterflies.

Karen writes~
Could you send me some information on zinnias? I have a lot of seeds from last year which I want to plant this year. Any advice on when, where, and how would be welcome. I also kept marigold seeds. Will they come back if I plant them?

A. Both your seed types will be very good for growing new plants this spring. Now is the time to start the germination! Tip out some seed compost or fine, sterilized potting mix [available from nurseries or garden centers, for seed propagation] from its bag on to your potting bench [or polythene-covered kitchen table!], fluff it up and make sure it is moist but not soggy. Ensure that the pots for seed sowing are clean and gather together everything else you will need: clingfilm or glass, a watering can with a fine-holed spout, labels and marker pen, and a presser as a pot, if desired.

Start by filling pots about half a dozen at a time. Fill each pot loosely to the brim, wipe off the surplus level with the rim of the pot then tap the pot on the bench to settle the compost; finally, firm very gently to level the surface. The surface of the compost should be about 1/4 in (6 mm) below the rim of the pot. Now the seed must be sown thinly and evenly over the surface of the compost.

For all but the largest seed, I find that the best method is as follows:

Place the seed on a piece if white paper, creased down the middle. Tap the edge of the paper with index finger to encourage the seed to roll off the edge and on to the compost. This way you can see exactly how much seed is falling on to the compost, and by moving the paper back and forth as the seed falls, the surface can be covered evenly. Larger seeds such as your marigolds and zinnias need less careful sowing and can be redistributed over the surface of the compost after sowing by moving them with the point of a pencil.

Very small seeds like those of lobelias, petunias and begonias can be tricky, but the method I have described will distribute the seed evenly, although this is less easy if your eyesight is poor! The old trick of adding a small amount of very dry sand to the seed, mixing thoroughly and sowing the highly visible mixture, works well. Large seeds can be sown in individual pots, thinned to one as they develop and then potted on before planting out.

After sowing, most seed needs a covering of compost, although plants with small seeds like begonias and petunias can simply be pressed gently into the surface of the compost. Over the years I have found that this gentle pressing is very useful, reducing the amount of fine compost for sifting over the seeds to a covering as deep as the seed itself. Some gardeners use an old kitchen sieve for this purpose. Vermiculite can also be used as a seed covering but is less easy to manage than compost. Immediately after sowing, write the label giving the name, source of seed and date of sowing.

Once a few pots have been sown, they need watering. I prefer to water gently with a fine rose on a watering can, tipping the can to get the water flowing before moving the spray over the pots, then moving it away before stopping - this avoids huge drips disturbing the seeds. Some gardeners prefer to stand their seed pots in a bowl of water so that water is soaked up from below until the surface darkens; but when the pots are removed, peat-based composts tend to shrink away from the sides of the pots.

In either case, it pays to add a copper fungicide to the water to help prevent 'damping off'. Most seeds do not need any more darkness to encourage germination than is provided by their covering of compost. If large seed trays have been used, a rectangle of glass and a piece of paper can cover each tray. On a small scale, this is more difficult. Fine, uncovered seed is in particular danger of drying out and here a piece of clingfilm stretched over the pot is useful. Some gardeners use rounds of glass or rigid plastic, some use larger sheets of glass to cover a number of pots.

Seeds should be checked twice a day as some, like marigolds and dahlias, germinate very quickly. As soon as they appear, any glass or clingfilm should be removed. At this stage the pots are moved to a slightly cooler temperature where the seedlings can grow on until the seed leaves have expanded. Watering should be checked regularly, and a copper fungicide added to the water as a precaution against damping off. Before long, they will be ready for transplanting into your garden beds, after your last frost date.

Assistance from: discoveringannuals.com

Isleman writes~
I am cutting the last of summer zinnias and enjoying them in the house. When they wither in the water, I cut off the heads and lay them out to dry. I want to save the seeds to plant next summer. Will this work, or what is better?

A. It may or may not work this way. First, you are not allowing the seed to develop on the plant. If one cuts a flower off when it is fresh, the viability of the seed is very much in question. Many, if not all, the seeds inside will be immature and will not sprout next year.

Follow Mother Nature and allow the flowers to dry and drop petals as is, on the plant, outside. Then, come in and cut those flower heads off, lay on dry newspapers inside where is warm and dry and allow to lay there undisturbed.

After about 2 weeks, go in and remove the dead debris as petals and sepal [shell] parts around the seed capsule. Inside will be a bunch of large, black to brown seeds and these you may then place in a paper envelope, label as to what they are, and store a ll winter in a drawer away from any interference.

In the spring, you can sow these seeds in the garden beds just as you do the ones you purchase. Or, you can start them early inside in flats under lights and transplant the seedlings outdoors after the last threat of frost.

Enjoy! It is a super way to learn about horticulture.