Coleus...help!

katsu(z5IL)March 14, 2004

I love coleus...just can't grow them! I've tried for several years (potted and in the ground) and I'm starting to think I don't have the right kind of lighting conditions.

Basically, in full shade they just sit there and show minimal growth. Sunnier areas result in dull, faded coloration. Even dappled sun/shade hasn't produced the spectacular coleus I see in photos.

I'm not new to gardening and successfully grow hostas, perennials, grasses, etc. So this brown thumb with coleus is bugging me to no end! Can some of you help?!! I'd appreciate hearing how yours thrive: planting mix for containers, light preferences, fertilizer, water....any suggestions are welcome. I refuse to give up on these beautiful plants!

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maineman(z5a ME)

Katsu,

"I'd appreciate hearing how yours thrive: planting mix for containers, light preferences, fertilizer, water..."

This year I have started several kinds of coleus under overdriven fluorescent lights on Premier Pro-Mix BX with a light covering of milled sphagnum moss (to help prevent damping-off.) I pre-moisten the planting medium, using melted snow water, which is equivalent to distilled water, but free here during this season in Maine. I place the tiny seeds individually with a moistened toothpick. I don't attempt to cover them, but I do make sure they are in good contact with the moss by nudging them with the toothpick if necessary.

I germinate them under light, with my timer set for 8 hours of dark and 16 hours of light. I cover the flat with plastic until the tiny green cotyledons begin to show and then remove the plastic so they don't get leggy and susceptible to damping-off. I water them with one-quarter strength urea-free soluble fertilizer with trace elements; one quarter teaspoon per gallon of snow water.

I have made several plantings and my more mature trays now have leaves about one inch long. So they are still quite small, but showing their colors and beginning to accelerate in growth rate.

About Memorial Day I will harden most of them off and plant them out in a few shady spots. This will be our first experience with coleus in Maine, so I can't brag how well they may do in our landscape. The deer may think they are delicious. Outside I can fertilize them with formulas that contain urea. I may keep a few choice specimens for indoor plants. I have had previous success growing coleus to maturity under fluorescent lights. I would like to learn to adjust their day length/night length to prevent them from flowering and trying to go to seed.

-- Burton --

    Bookmark   March 17, 2004 at 12:48AM
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shade_tolerant

Katsu I grow lots of coleus from seed, cuttings and buy plants online and at garden centers. They are my favorite plant along with hostas. They are also easy! I carry over cuttings through winter and then grow them outdoors in pots on the deck and in my backyard. Mine don't get any full sun as there isn't any in my yard. They love water and I have to water them every day in summer. I feed them with Miracle-Gro about once a week in the growing season. You can pinch the ends if you want them bushier. I pot mine in regular potting soil, I used Scotts last year and also don't give them too big a pot so they are forced to put out more leaf growth than roots. You really shouldn't have any problem getting good coloring from your coleus, maybe you might want to pick the more intense colorful varieties. I don't know if you've checked out coleusfinder.org, it's a great site. These are two pics of ones I grew last year, Glennis and Dipt in Wine.

Glennis

Dipt in Wine

    Bookmark   April 1, 2004 at 11:42AM
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kdjoergensen

Coleus like aerated soil but which stay consistently moist. The soil must not dry out or the leaves fall off.

Initally, as seedling, they require very little water, but once larger, their requirements for water is huge.

The best way is to loosen the soil thoroughly and deeply. Mix in plenty of organic matter, such as compost. I like to add a handfull or more of hydrated watering crystals (e.g. hydrate the crystals first with water in a bucket, mix into bottom of planting hole with compost and then plant on top of this mix).

During the first 2-3 weeks make sure you keep the plants watered at least twice per week or as needed. Mulching around the plants will help with dehydration.

Avoid planting in cool soil. Planting coleus outdoors takes patiens especially in zone5. It is better to air on the side of waiting a bit longer, than plugning them into the cold soil and watching them die within days.

In early June after a few nice hot days, mix in plenty of compost as above and then plant the coleus. Water well once to settle the soil and then keep an eye on it for next week or two.

- soil must be well draining. standing water or heavy compacted clay is equal to death of the plant. dig deep, mix in plenty of compost, and use watering crystals (already hydrated) in the bottom
- plant in warm soil. better to wait two weeks extra
(better water with tepid water until fully established)
- never let the plant dry out once outdoors.

Coleus benefit tremendously from being pinched back, e.g. having the growing tip removed. Do this several times during the growing season, especially in shade where the coleus tend to grow tall. Do not crowd with too many plants close by. Give them room to expand a bit.

    Bookmark   April 2, 2004 at 4:40PM
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katsu(z5IL)

Thanks for the infomation!

Hi Shade!...Imagine bumping into you here :-) So glad to read your response. As always, your plants are wonderfully lush and so beautiful! I am DETERMINED to grow some pretty coleus this year. Kenneth, I especially love your details! It's helped me evaluate what might have caused poor results. I tended to plant them eariler and failed to add compost...kept the soil too wet. Most of my attempts were in pots with a couple of leftover (from the pack) in the ground. Thinking also the "potting soil" was too heavy and not a good quality light mix. Thanks again for the tips!

    Bookmark   April 3, 2004 at 11:36AM
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kdjoergensen

Thanks for the nice words, katsu
If I had to summerize the three most important things for coleus based on many years of killing them year after year:

- do not be in a hurry to plant them out (let soil warm up)
- perfect drainage is crucial (pudles of standing water even for a short time = death)
- never, ever let them dry out (consistently moist)

    Bookmark   April 5, 2004 at 1:28PM
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enshalla_hotmail_com

Hi
Sorry to hear you're having troubles with the coleus. I can see also nobody's answering your question ! I've started 10 coleus seeds, kong series on the 1 september. they germinated september 6 and now on october 16 (about 6 weeks later) only 1 set of true leaves have appeared, only 1/2 inch long but are coloured. rate of germination was 80%. I guess they're slow growers from seed ! light conditions i'm providing is a window facing south and a temperature of 18C. The package says you can grow any time of the year. hope this helps. I'll update in another 6 weeks

    Bookmark   October 16, 2008 at 5:41PM
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tree_gent(z8b SC)

Because this is related to some comments here, I thought I'd avoid starting a new thread. Hope this isn't a threadjack. In answer to the original question, I would say make sure you have sun-tolerant coleus (Dark Star, Plum Parfait, etc) and plant in at least half-sun once things are completely warm.

My question: Is there some special treatment that coleus seeds need for rapid germination? Last fall I collected seeds from several of my plants, stored them in an envelope indoors with no special care. Planted them this June (sprinkled on potting mix in a container, then watered). No germination seen after a couple weeks, so I figured I'd mis-handled them. But in September a few started sprouting, and in October there were dozens of seedlings. I'll have to dig them up and baby them through the winter if I want to keep them. I must say that the ones that sprouted earliest have grown to very nice size in only two months. Any suggestions to improve things next time?

    Bookmark   November 2, 2008 at 7:20PM
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