Tips can help get iris, tomatoes to blossom

posted June 25, 2018 8:21 a.m. (CDT)
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by / Bev Carney | Gardening Columnist

My iris plants didn’t produce all that many flowers this year. A friend tells me it is time to divide them. Is this true? If so, how do I go about it?

Iris rhizomes multiply and over the span of three to four years will produce enough new rhizome branches that the plants get crowded and produce fewer and fewer flowers. At this point, they need to be dug and divided. The optimal time for this is just after the bloom fades because that gives them plenty of time to re-establish themselves before winter sets in.

Iris are super hardy and you can divide them up until early fall if necessary. The process is fairly simple: First cut the leaves back to 3 to 6 inches. This makes the plants easier to handle and also cuts down moisture loss from the plant. Then dig up the mass of roots. This can be a difficult physical job if your plants haven’t been divided in ages. Since you will be cutting the rhizome mass anyway, you can certainly dig down and cut off a portion of the plants and work with small sections at a time. Do not worry if you don’t get all of the “roots.” Cut your freshly dug rhizomes into 3 to 4 inch sections and replant with enough space between these clumps to allow for expansion over the next few years. Iris prefer a shallow bed so set the rhizome so that it is barely covered with soil and then water it in and then mulch it. You should see lots more blooms next year.

I set out my tomato plants in late May but I don’t yet have any fruit. I don’t expect to have ripe tomatoes this early in the season, but I think I should have some small little tomatoes. Is there something wrong?

Temperature extremes can cause blossoms to drop from the plant before they develop into tiny tomatoes. Nighttime temperatures below 55 degrees or hot days with temperatures in the 90s and nights in the 70s can stop fruit production. This year our temperatures have ranged rather dramatically from cold to hot and back again. So it could just be a temperature issue. While you can wrap tomato cages in a row cover to concentrate heat, it is hard to cool them down during a heat wave. With luck, our temperatures will soon stabilize to lovely summer temperatures without extremes.

Just as heat or cold can stress the plants, too much or too little water can also cause the plant to go into survival mode, dropping the energy-absorbing blossoms. Likewise, too much nitrogen fertilizer, whether organic or chemical, can produce a bounty of leaves at the expense of the blossoms.

You might want to check the varieties you are growing. Some types do better in hot conditions, some do better in cold and others have proven to be good producers despite the weather. My all-time favorite hybrid is Big Beef, which seems to come through for us regardless. Some varieties produce fruit more quickly than other types, so check the maturity date for your plants and see how long it takes. Your plants could simply be very slow growers with fruit not expected until late summer.

You could also have pollination issues. While tomato plants are usually pollinated by the wind causing the plant to quiver, insects do their job too. You could enhance pollination by providing flowers in the tomato patch to attract insects, shaking the plant periodically to scatter pollen or even try hand-pollinating the plants. For more information on that, see ​​edible/​vegetables/​tomato/​pollinate-tomatoes.htm.

Beverly Carney can be reached at

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