Question #1

potted plantRuby56 asks: I purchased a potted hosta and a coreopsis mid-summer: both in pots. Apparently, they are both supposed to be planted in the spring. Would it be better to plant them now, in the fall, or somehow overwinter them until spring? I have had this problem before, so a more general question would be - what if you cannot plant a plant when you are supposed to???

carrielamont answers: Aha! Who told you they should be planted in the spring? Most perennial plants--your two included--will be much happier waiting until the fall. (Chrysanthemums are a noteable exception, see Question #2 below) See this article for more advice. (Plant Perennials In the Fall Instead of the Spring) I think people are advised to plant in the spring for a variety of reasons which have nothing to do with the needs of perennials. Yes, annuals are most often planted in the spring in temperate climates. Yes, annual crops (tomatoes, peas, wheat, you-name-it) are often planted in the spring. Yes, established plants and trees are leafing-out. Yes, many animals and birds mate and/or bear young in the spring. Yes, the shelves are cleared of Christmas decorations and retailers need to fill them with lawn fertilizer, seeds, pansies and--you guessed it--plants for you to put in your new garden. But no, perennial plants usually do NOT need to be planted in the spring, including hosta and coreopsis. Please try to be kind to them until you plant them, and if you get a extended stretch of cool or rainy weather, you could try planting them now. (I've only visited my grandmother in PA as a little kid in the winter, and it was always cool then.) You know that most hostas like shade and coreopsis like sun, right? Good luck, and enjoy.

Melody adds: You can keep potted perennials and shrubs happy in their containers until conditions are right for planting by shading them from the hottest sun and watering them regularly. I have a Loropetalum that I purchased earlier this year that I've kept in its pot all summer, waiting until it was cool enough for me to prepare the planting area. I purchased 3 that day and the other two are already planted. I moved the other one where it gets bright, but filtered light and sometimes watered it twice a day during the worst of the summer heat. I'll plant it here in a week or two since the temperatures have moderated a bit. Nursery stock live several years in their containers before they're sold, so just make sure they have ample water during the dry periods and they should live through summer or winter just fine.

Question #2

mumskantzklan asks: Are there hardy mums that will come back each year in zone 5? If so, what are the names and what do I have to do to get them to come back each year...thanks

Melody answers: There are many hardy mums that will thrive in your zone 5 conditions. The key is to get them planted early enough in the year that they have time to establish a good root system before freezing conditions. Personally, if I were planning on maintaining hardy mums year-round, I'd plant them in the spring. When they start to show some growth, pinch each of the growing tips to encourage branching. Do this again around the first of July. This helps shape the plant into the familiar rounded form. You'll trim them back and mulch when a freeze cuts them down and they should return in the spring just like any other perennial plant. Be sure to maintain a pinching schedule or they will become tall and straggledy. Emperor of China, Venus, Pure Delight and Peace are all hardy mums that will live in zone 5 conditions and we have participating PlantScout vendors attached to each PlantFiles page.

Question #3

green shouldersdebflowergirl asks: I have San Marzano paste (Roma) tomatoes-huge, pointed at the ends and very meaty-- and I grow them frequently. Often however they don't ripen well on the shoulders. Any thoughts as to why? Thanks.

critterologist answers: "Green shoulders" on tomatoes usually don't have anything to do with sun/shade conditions, fertilizers, or other growing factors. Some tomato varieties simply tend to have them. If that part of the tomato is too firm or too tart for my taste, I just trim it off. I did get curious about the "why" of it, though, when I read your question. Modern "improved" hybrids don't have green shoulders, and it turns out that improving them in that way may explain some of the difference in taste between hybrids and the often yummier heirloom varieties. I came across a July 28, 2012 piece by Susan Milus on the "ScienceNews" website that quotes a June 29, 2012 article in Science by Dr. Ann L. Thomas Powell, PhD: "getting rid of... green shoulders, turns out to have sabotaged a gene called SlGLK2 that boosts sugar and other sources of flavor in the ripe tomato... For years... breeders assumed that a ripe red tomato got all of its sugars from the little photosynthetic engines known as chloroplasts in the plant leaves. It turns out, however, that a green-shouldered tomato gets about 20 percent of its sugars from its own chloroplasts. Without a functional SlGLK2 gene, the ripening tomato forms fewer and punier chloroplasts that don't deliver, Powell and her colleagues have found." For a more complete summary of this study click here.

Question #4

mandevillakountrykitten asks: I bought a beautiful Mandevilla plant and just left it in the pot as I know I have to bring it in in the winter time...I put it in a bigger pot as it was root bound. Before I did I noticed the leaves turning brown and it dying. What happened to it, it looks terrible? It's been hot here so I have been watering it.

critterologist answers: kountrykitten's mandivilla plant looks hot & dry despite being watered. My guess is that it would appreciate a bigger pot. Rootbound plants often just can't soak up the water that they need. You could try soaking it in a saucer or bucket of water for a few hours instead of top watering, or you could give it a bigger pot. Also, as hot as it's been, the black plastic of your pot might be part of the problem... even tropical plants can "cook" their roots in a black pot. Try shading the pot or insulating it somehow. And keep the plant out of full sun while it recovers.

Question #5

dahliadrapes asks: How do I feed my dinnerplate dahlia to be sure the flowers are as big (9inches] next year?

wind answers:My late cousin was an expert dahlia grower. His dahlias were the biggest and most beautiful dahlias I've ever seen. He always told me never to over feed dahlias. In addition to not over feeding them, I've learned that in order to produce the huge dinner plate size, dividing the tubers is essential. Swan Island Dahlias, a leading dahlia grower in the United States located in Canby, Oregon says dahlias are best fertilized with a low nitrogen fertilizer - like what you might use for vegetables. They recommend a high percentage of potassium and phosphorus fertilizer, such as a 5-10-10, 10-20-20, or 0-20-20. They suggest first applications within 30 days of planting, then repeated again about 3 to 4 weeks later. According to Swan Island, avoiding high nitrogen compost and highnitrogen water soluble types will help avoid weak stems, small blooms, or no blooms, and tubers that rot or shrivel in storage.
Good luck with your dahlias!

Question #6

indoor gardeningkhushi24u asks: Hi All, I am beginner in Belgium and I am searching for some one who can guide me in Indoor Gardening. I buy some herbs like mint, cilantro & basil but after some time my plants are died. I don't no why... I want to do it...

critterologist answers: I think probably the windowsill light is inadequate (a cheap fluorescent fixture might be the answer), and also it looks like the plants might be overwatered, leading to mildew & other problems. Basil & Mint like water, but they don't like soggy. I haven't had a lot of luck overwintering basil or mint inside myself; after a while the plants just seem to dwindle and give out. But the good news is that basil & mint cuttings (maybe cilantro too, not sure) are readily rooted in water, so you might be able to periodically renew your plants by taking and potting up cuttings, giving yourself a renewable source of fresh herbs indoors. Basil and cilantro can be re-started from seed, too. Specific mint varieties must be started from cuttings, but "generic" spearmint and peppermint seeds are available.

sallyg adds: I had about the same exact thoughts on the herb/windowsill thing. I've long thought how that really must not work realistically. They can't possibly thrive under windowsill conditions, and they'd have to thrive to be able to be harvested, right? I've never tried it personally. But I much doubt you'd have any success on renewing them over winter, to any great extent, unless you correct the light problem.

Remember, if you have a gardening question that you would like to suggest for this feature, post it here.
Our writers and admins will handpick a few of your questions and answer them in an upcoming Ask-a-Gardener, one of our Saturday morning features. Other questions may be moved to one of our other forums so your fellow members can help you

A big thanks to member 'DreamofSpring' for her image of the dinneplate dahlia. 'kountrykitten' and 'kushi24u' supplied their own images. The others are courtesy of Melody.