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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I planted eight arborvitaes last spring and fall and they are not growing as fast as I had hoped. I read that you recommend Miracle-Gro. Is there a particular formulation of the product that I should use? Do you suggest a spray or granules? My soil is very sandy, so it drains very quickly. The plants get a lot of sun during the day. I used fertilizer stakes earlier this year but saw that you don't like those, so I'll stay away from them next time. Any suggestions you might have for fertilization or a watering schedule to get them growing would be greatly appreciated. (Charleston, S.C.)

A: If you planted the American (eastern arborvitae), you are up against the limit for growing this species in your area. This means that the plants may never show much vigor and limp along during the hot and humid summers of your area. If you could tell me exactly what the genus and species of your arborvitaes are, I could pass more accurate information on to you. For example, if you have a Thuja orientalis (oriental arborvitae) planting, these are more adaptable to the high humidity and temperatures of your area. My suspicions are that you are struggling with the eastern arborvitae. If that is the case, you would be better off replacing this planting with a more adaptable species. Miracle-Gro and others like it are good, all-around fertilizer products that stimulate new growth. However, being as high in nitrogen as Miracle-Gro is, the stimulation may be too much in some cases. If you can locate a fertilizer on the market that has a 10-8-6 or a 10-10-10 analysis (or something close to these numbers), you would be better off using one of those products. In the long run, either granular or liquid applications are beneficial. Fertilizer should be applied in the spring prior to new growth emerging and not going into the fall of the year. Doing so now may cause growth to occur, and it would not harden off in time for winter.

Q: I have large pumpkins and a ton of buttercup squash in the garden. We will be going on vacation, so I wonder what temperatures they will tolerate in our absence. Thanks for your time. (email reference)

A: Cold damage depends on the degree of cold and its duration. It also has a lot to do with canopy protection. The first light freeze will take out the canopy foliage and leave the fruit pretty much unharmed. Ideally, it should be harvested at that time. If that isn’t possible, then hope for about a week to 10 days of balmy weather with no further freezes. Harvest the pumpkins and squash at your earliest convenience after that. I would strongly suggest getting a frost blanket and placing it over as much of your garden as possible to provide an extra layer of protection. Frost blankets are not expensive and are reusable for several years.

Q: During the drought this year, we have let our sod go dormant. At the end of July, we started watering about a 1/4 inch per week in an effort to keep the crowns of the plants alive. I suspect that this has not been enough water for the sod on the south side of the house that bakes in full sun each day. How soon after a soaking rain, which hopefully will come soon, should I expect the sod to green up again? What is the best way to handle reseeding in the areas that don't rebound? Is it best to do this in fall or spring? (Moorhead, Minn.)

A: The 1/4-inch weekly watering just might have kept most of the crowns alive. However, as you said, the grass with the southern exposure in hot sun all day may just have kicked the bucket. A good soaking rain (more than an inch delivered during a 24-hour period to minimize runoff) would result in the grass showing recovery in a week or less. Reseeding is best done in the fall because the competition from weed seed would be at a minimum. Also, the soil still is warm enough to facilitate good germination. If the soaking rains do show up and the turfgrass responds by regreening, it would be a good time to give the grass a shot of winterizing fertilizer. It also would be a good time to wipe out any broadleaf weeds that may have moved in and languished in your dry, noncompetitive turfgrass this summer. Again, there are plenty of products available on the market to do a good job.

Q: A lady I know has patio blueberries and wants to know how to winterize them. Should they be moved indoors? Thank you. (email reference)

A: Don’t bring them inside. Plant them adjacent to the house foundation, pot and all, after a good killing frost. Water the plants well and then cover them with leaves held down with chicken wire or a Styrofoam cone. Unless we have a brutal, open winter this coming season, the plants should survive.

Q: We have three types of grapes on our vines. We checked the Brix numbers (sugar content) and one group measures 18.5, another 19 and the other 21.5. With the cool mornings, we are wondering when to pick the grapes for making wine. Does an early freeze affect the grapes? After the harvest, do we store the grapes in the freezer for later use or should we start the process of making wine? Also, do we need to prune the vines after we harvest the grapes? (email reference)

A: It is best to harvest grapes before a hard freeze. The first light freeze will take care of the foliar cover. Make sure it is a light freeze where the temperature just touches 31 to 32 degrees, not down into the mid-20s. Then harvest and start the winemaking process. The best time to prune is mid-March while the plants are still dormant but not under the threat of extremely low winter temperatures. Enjoy the harvest!

Q: I took cuttings from a creeping juniper more than two months ago. I applied hormone rooting powder and planted the cuttings in clay soil. I have watered the cuttings every few days. Some of the plants have small berries but the leaves are brown and there is no sign of new leaf growth. It’s starting to get cold in my region. What are the chances that these have rooted and will survive? Thanks in advance for your response. (email reference)

A: Typically, junipers are easy to root. I’d give them a tug to see what is going on. Because I don’t know where you live and that they were planted in clay soil, I can’t give you an accurate estimate of the chances that they have rooted. The normal procedure for rooting is to provide a media that is well-aerated, such as a 50/50 sand/peat mixture or sticking them in straight vermiculite or perlite, and then keeping the media moist until rooting is accomplished. Based on your description of the cuttings, my best guess is that they are dead. The berries that were set were done as a last gasp of species survival.

Q: How do you winterize raised strawberry and raspberry beds? Do you have any recommendations? (email reference)

A: Pile raked leaves on top of the beds and then cover the beds with frost blankets. Also, be sure the plants are well-hydrated before freeze-up. The ice will protect them from damage caused by extremely low temperatures. This all assumes that you planted a regionally hardy variety of strawberries.

Q: I acquired a dwarf green schefflera back in March. The plant was very healthy and it grew well the first part of the year. However, the last few months, it has not grown very much. I think it is because it is overcrowded in the pot. Should I take it out of its pot, shake off all soil and separate it into individual stems? I then would plant each of the stems in its own pot. Would that help the new plants grow faster and better? Thank you. (email reference)

A: There might be some sacrificial plants involved in this separation. However, if you are willing to take the risk, go for it. Pick the plantlets that you want to survive and then separate/prune all other roots away from that plant’s primary root system. Given the previous environment it was setting in, your separation and replanting efforts should pay off with about a 90 percent level of success.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or email

For answers to general horticultural questions, go to

NDSU Agriculture Communication – Sept. 26, 2012

Source:Ron Smith, (701) 231-7971,
Editor:Rich Mattern, (701) 231-6136,
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