February "In The Grow" - Indiana Yard and Garden - Purdue Consumer Horticulture

February “In The Grow”

Q. I am wondering what happened to my tomato plants this past year. Early in the season, they started getting yellow leaves at the base of the plant. Then, the leaves dried up; the complete plant almost turned that way. I have them caged, and they grew way above the cages. The tomatoes seemed to be good, but the plants were terrible. Hope you have an answer. – Mrs. Otis Rupright

A. Fusarium and Verticillium wilts are common wilt diseases of tomatoes. The first symptom is a yellowing of the lower leaves, which then progresses upward through the plant. These two diseases are very difficult to distinguish from each other. No chemical control is available. Destroy infected plants as soon as possible. In the future, choose resistant cultivars to help prevent diseases from starting. Cultivars with resistance are noted as such by the letters V or F following the cultivar name.

Walnut toxicity also causes the same yellowing of foliage. Tomato plants are particularly susceptible to juglone, a chemical given off by walnut trees. Black walnut leaves, bark and wood chips should not be used as mulch or compost in the garden.

Q. I was wondering if you could tell me why my cactus is not blooming. I have had it for two years and it still hasn’t bloomed. The person I got it from said it used to bloom every year. I have repotted it and have it sitting in a lighted area. I just moved six months ago, and before I moved, it wasn’t

completely in the sun, although it had plenty. If you could let me know what I am doing wrong, I would appreciate it. Thank you. – Submitted via e-mail

A. Most cacti require bright, sunny conditions and should be in a southern or western window. Interior lighting probably is not adequate. Moving and transplanting both can throw the flowering cycle off track. The plant has to adapt to its new soil and site and that can mean a lack of flower production. Give it bright light, make sure you don’t overwater and fertilize with a houseplant food once every three months during the growing season.

Q. Another reader mentioned the pinching of mums up until July 4; however, I’m wondering what I need to do to prepare my hardy fall mums for the winter. This is the first fall that I’ve planted mums, and I am at total loss as to what type of care they need to survive the winter. Any tips you can give me will be most welcome. Thanks! – Jo Zimmermann

A. Florists’ mums generally are not hardy at all. Even hardy fall mums (typically purchased at a garden center) should have the word “hardy” in quotation marks in my experience! Typically, about one-third of the plants return each year. Now, before all of you with 10-year-old mums write me, let me add that it depends upon the site, soil, recent weather conditions and mum cultivar.

A southern exposure against a foundation provides warmer soil and increased overwintering success. To increase the chance of overwintering, apply a one-half inch layer of mulch in the fall after the ground has frozen. Consider planting Dendranthemum (they have been reclassified from the Chrysanthemum genus) ‘Mei Kyo’ or ‘Clara Curtis.’ They are among the hardiest mums available.

Q. I have some questions about peonies, irises and rhubarb. Peonies: When do I transplant and how do I divide? Irises: When do I transplant and how do I divide? Rhubarb: Our rhubarb patch has been in the same spot for years and has grown quite large, but the last two years the stalks have become small and spindly. Help! What do we do? – Phyllis Heinrich

A. Peonies can be divided in late summer, but I prefer to tackle it in early spring when the shoots are only about 1-inch tall. I may sacrifice the blooms for that season, but it’s easy to handle the divisions and the plant recovers quickly. Dig the plants with a spading fork and lift as much of the roots as possible. Then, use a sharp knife to cut the larger roots into smaller pieces. Each new piece should have both roots and shoots. Replant the pieces at the proper depth. For peonies, this is surprisingly shallow. Set peony roots so that the buds, or eyes, are only 1-2 inches below the surface of the soil. Each root piece should have at least three good buds.

Divide iris every three to five years to ensure continuous blooming. In late summer, lift the clumps with a spade or fork. Divide with a sharp knife so each rhizome has a green shoot coming from it. Cut the leaves back to a fan about 4 inches high. Discard the old unproductive rhizomes from the center of the clump and any rhizomes that are soft or rotted. Plant the iris 18-24 inches apart, just along the surface of the ground. Spread the roots underneath the rhizome and cover them with soil. Leave the surface of the rhizome exposed to the sun’s rays.

Rhubarb stalks can become thin and small for several reasons, including lack of fertilization, overcrowding, crown rot and poor soil drainage. If your plants appear healthy, they probably need to be divided. Plant the divisions so the buds are no deeper than 2 inches. Fertilize annually after harvest with one-third pound of ammonium nitrate per 100 square feet

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