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Frequently Asked Questions (FAQs)

Do roses need lime?

"Do rose plants need lime?" is a simple question with a not-so-simple answer, or at least not a short complete answer. First, the rose plant does not "need" lime; that is, lime is not a nutrient or other chemical used by the plant. Rather, lime is a soil modifier that is used to make soils less acidic.

A common phrase you may hear in reference to the use of lime is, "raise the pH" of the soil. The relative acidity or alkalinity (the "pH") of soil is measured on a scale of 0 to 14, with 7 being neutral (neither acidic or alkaline). Lime is alkaline, so adding it to soil can make the soil more alkaline (therefore, less acidic), thus "raising the pH".  An example would be: if your soil pH measured 6.0, you might add lime to raise the pH to 6.5, thus making the soil less acidic.

Rose and other plant roots are able to efficiently extract nutrients from soil when the soil's pH is within a certain range. This ideal range varies depending on the type of plant. The further the pH varies from the ideal range, the less the plant is able to gather its needed nutrients, and the poorer the plant's growth will be. The ideal soil pH for roses is between 6.5 and 6.8, but good rose growth can occur between 6.1 and 7.1. Adding organic matter (such as compost) to soil can make nutrients more available to plants in a wider range of pH.

Before adding lime, you should have your soil tested to determine its current pH. Changing the pH of your soil with lime is a slow process. You should wait a year after applying lime before doing another pH test to determine is additional lime is necessary.

Further information is available in an article on the Articles on Rose Growing page. Click on Roses in Alaska: Soils, pH, and Digging the Rose Hole to view this article.
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Rugosa Rose Hips Not Developing

I planted a rugosa rose about three years ago that has light pink blooms and is supposed to produce a lot of hips. So far I have only gotten a few full ones and the other seem to dry up and fall off or just stay small on the plant. Any ideas on why this is happening would be greatly appreciated. [August 2003]

There are several things that affect the production of hips on a rugosa. 

First, not all rugosas are heavy hip producers. One of the light pink rugosas is 'Frau Dagmar Hartopp'. This lovely, fragrant rose has a reputation for good hip production, but not all hips fully develop; the ones that do develop are very large. 

If you have a rugosa that is expected to produce an abundance of hips, then there are three possible explanations for less than expected production. First, it may be a result of lack of pollination. Second, it may be a lack of water sufficient to plump all hips, and the plant will selectively drop some hips. Third, it might be a lack of an element in your soil. Some rose growers use Epsom salts to great advantage. Applied sparingly in the early spring (about a quarter-cup sprinkled around the root zone of the rose), gently agitated into the surface soil, and then watered in, it has produced remarkably improved vigor in roses. 

Chemically, Epsom salts is hydrated magnesium sulfate (about 10 percent magnesium and 13 percent sulfur). Magnesium is critical for seed germination and the production of chlorophyll, fruit, and nuts. Magnesium helps strengthen cell walls and improves plants' uptake of nitrogen, phosphorus, and sulfur. So, this additive improves not only the vigor of the overall plant, but also aids in the production of hips.

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Planting Rose Seeds

My rose plant grew a hip and I would like to plant the seeds but don't know how. I can't find anything about it in my internet search. [July 2003]

Two articles about seed germination are available on the Articles on Rose Growing page. Click on the links to Seed Germination of Wild and Cultivated Roses and Starting Roses from Seed to view these articles.

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Rooting Rose Cuttings

What is the most successful way to propogate a rose from a cutting. In soil?? in water??? if soil what mixture?? any helpful hints!!! Thank You!! [June 2002]

Not sure how to propagate roses from cuttings? Step-by-step, here’s how:

1. Prepare the cuttings by cutting stems into pieces with four leaf nodes; remove the two bottom leaves, leaving the two leaves intact at the top end of the cutting.

2. Dip the bottom cut in rooting hormone, if available. This is optional for most roses.

3. Carefully insert the cutting into moist, sterile potting mix. The two bottom leaf nodes should be completely covered.

4. Cover the container(s) with a clear plastic “tent” to create a moisture-retentive greenhouse. A recycled aquarium, inverted over the container or tray, works well.

5. Keep the cuttings under light for 12-16 hours per day in a cool room. Keep the potting mix moist, but not wet-you want the cuttings to root, not rot.

6. When the cuttings begin to produce new leaves in late winter, gradually remove the plastic covering. By May they should be ready to pot up, harden off, and plant out for the summer growing season.

If you prefer to try rooting your cuttings in the garden during the summer, follow steps 1 & 2, then "plant" the cutting in a lightly shaded area of your garden and water it well. Cut the bottom from a green, plastic 2-liter soft drink bottle and use the top portion of the bottle as a miniature greenhouse. Keep the soil evenly moist and leave the bottle over the cutting until the following spring. If the attempt is successful, the cutting should leaf out at the same time as other roses in your garden -- carefully transplant the rooted cutting to a permanent location.

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Fertilizing Shrub Roses

I have just planted a variety of English, Buck, and some Canadian Explorer roses, along with a 'Hansa'. When, with what, and how much should I fertilize these new plants? [May 2001]

The roses you mention (English, Buck & Canadian, as well as the Hansa) are all shrub-type roses. Typically, you want them to grow fairly slowly and "bushy" -- this means very little fertilizer is needed. Organically, an occasional (yearly) mulching with compost or well-rotted manure is usually sufficient. If you prefer chemicals, a one-half dose of a balanced granular fertilizer in the spring is sufficient.

Avoid fertilizer for the first year – the roses will find plenty of nutrients in the soil for their first year's growth – any additional will tend to "burn" their new roots and could actually slow their growth.

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Fertilizing Hybrid Tea Roses

When, with what, and how much should I fertilize hybrid teas that I have planted in containers? [May 2001]

Hybrid tea roses are heavy feeders due to their desired rapid growth. As you annually prune them, you are removing a great percentage of their previous year's growth. They will need sufficient nutrients as they replace this growth during the growing season. 

Hybrid teas can be fed with liquid or granular fertilizer. Wait until they are actively growing before feeding the first time. Use the amounts and frequencies recommended by the manufacturer on the label. 

If you intend to winter over container-grown hybrid teas, do not feed them after the first of August. If you are growing them as annuals and intend to discard them at the end of the summer, you can continue to feed them until frost. To winter over, you want the canes to “harden” and become woody – new growth is not woody and will not survive the winter. Hybrid teas will continue to produce new growth as long as they are well fed and have the summer sun and warmth. Stop feeding by August 1 and hopefully most of the canes will be woody by the time they freeze.

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Scattered Brown Spots on Rugosa Leaves

We planted our first Rugosa rose this May (bare-root) and it was looking great until this past week. It has now developed small, scattered brown spots on many of its leaves. It doesn’t look dry, and has gotten plenty of water. It’s in a well drained location, we’ve given a bit of fertilizer, haven’t seen any bugs. We’re in zone 2 in Anchorage. Any suggestions? [July 2001]

From your description, I suspect your rose has been sprinkled with a chemical (fertilizer or pesticide). Continue to water the bush – but don’t drown it – give it time and it will recover. The brown spots will not go away. In fact, some of the leaves may turn totally brown and drop off. However, your bush should continue to grow and should be “back to normal” next spring – provided it does not receive future sprayings of chemicals.

Rugosa roses are very disease-resistant and are usually not bothered by insects. You may occasionally notice some aphids, but the Rugosa roses don’t mind them. Indeed, they prefer the aphids to any treatment you may apply – and that brings us to the brown spots on the leaves.

Rugosas do not tolerate chemicals – fertilizers or pesticides – especially when applied to their leaves. They will usually drop all their leaves if they are sprayed with water-soluble fertilizer (foliar feeding) or if sprayed with an insecticide. A very light sprinkling of chemicals will often result in scattered brown spots on the leaves. Such a sprinkling could be from a breeze blowing some mist when a nearby plant or lawn was sprayed – even from a neighbor’s garden.

When it comes to fertilizer for Rugosas, less is best. Heavy, or even normal (as recommended on the label) amounts of fertilizers applied to the soil around the plant (root feeding) can result in the leaves “burning”. This usually shows up as the leaf edges slightly curl, then the leaves become dry and crisp, and usually turn yellow or brown. Rugosas usually do not need fertilizer the first year. In subsequent years, the best approach is a light (half-strength) application of fertilizer (around the plant’s base, not on the leaves) in the spring when the bush leafs out. If you really want to pamper them, their favorite treat is an inch or two of well-rotted compost spread around their base each spring instead of commercial fertilizers.

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Planting Container-Grown Roses in the Garden

I have two hardy roses – a 'John Davis' and a 'Sir Thomas Lipton' – that have thrived in containers on my deck. I would like to plant them in my garden, but should I do this now or in the spring? Suggestions on how to plant them and/or how to overwinter them inside? I live in Anchorage, zone 2. Thanks! [September 2001]

Now is an excellent time to plant your roses into your garden. Just be careful, when you remove them from their pots, to keep the rootball intact to avoid disturbing their roots. Water them well when you plant them, and be sure they are well watered before winter sets in.

Both of these roses are quite hardy in Anchorage, but may appreciate a winter mulch for their first winter. Either a mound of soil or compost, or a thick layer of clean (no seeds or weeds) straw will help protect their crowns. While not absolutely required, such protection is usually beneficial the first winter – especially it we have a late snowfall (like last winter), but is usually not needed in subsequent years.

If you do decide to mulch with straw, wait until the ground has begun to freeze and use a course straw with no seeds. If the straw has seeds, it may attract mice or voles that could then damage (and possibly kill) the roses.

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Last modified: April 18, 2004