Roses and grape vines are often grown together in home gardens for several reasons. First of all, both plants look fabulous, they can be very decorative and are easily grown even by inexperienced gardener. Second, any issue with the diseases will be visible on the roses, first. That is why roses are often grown on the edges of vineyards...
In home gardens, roses are grown almost exclusively for their decorative flowers and leaves. Grape vines can be very decorative plants, too, but they are commonly grown for the shade and grapes.
Requirements of the roses and grape vines are very similar, and although they do compete for the water, nutrients and sun, if you like them, feel free to grow them together.
Soil Types for Roses and Grape Vines
There are many types of soil, but generally, they are clay and silt soils, loamy soils and sandy soils. All these soils have their pros and sons.
The best soil for growing roses and grape vines is sandy loam soil, rich in organic matter, with pH around 6.2 - 6.5. Both roses and grape vines tolerate pH between 5.5 and 7.0, but this also depends on the rose/grape vine variety and, of course, rootstock plants. For short, keep pH around 6.2 - 6.5 and your plants will be happy.
Sandy loam soil also drains well, preventing excess water around the roots, which could lead to root rot and other root issues. Such soil also holds nutrients well.
When preparing the soil for roses and grape vines, check pH and nutrient level using home garden test kits - they are cheap and rather reliable.
If you want to increase pH, use lime, and if you want to decrease pH, use sulfur. Amounts depend on current and desired pH and soil volume (not just area).
When growing plants next to the new concrete walls, keep in mind that such walls leach lime over time and increase pH slowly. Old concrete walls (30+ years) also leach lime, but negligible.
Adding aged or dehydrated manure, compost, humus, and even mineral fertilizers, helps the soil to be fertile, well aerated with good drainage and keeps the soil slightly acidic.
During summer, adding mulch prevent water loss, but also decomposing mulch feeds the plants.
During vegetation period, both roses and grape vines require plenty of moisture and nutrients, but grape vines grow happily even in not so ideal conditions. Nonetheless, in good conditions, roses bloom often and grape vines grow vigorously, bearing plenty of grapes. Just don't add to much nitrogen - too much nitrogen can make plants grow fast and big, but those plants are actually weak and prone to diseases and pests.
Depending on the local climate and temperature, roses require at least 1 inch (~2.5 cm) of water, per week. High oscillations in soil moisture and nutrient levels should be avoided, thus, water plants more often with lower amounts of water. Similarly, add fertilizers every month - spread them over the area and gently dig them into the soil.
Note: personally, I never water grape vines, but the roses growing next to them, I water regularly. Similar is with keeping the soil fertile - twice a year, I add aged or dehydrated manure and some compost/humus and I try to add some balanced NPK fertilizer in small amounts on a monthly basis - regular digging in the fertilizers, keep the soil in excellent condition. IMHO, of course.
Growing Positions for Roses and Grape Vines
Both roses and grape vines need at least 4 to 6 hours of direct sun every day, preferably much more.
Growing grape vines on trellis and/or fences, provides sunny positions for roses next to the grape vines. When growing grape vines for shade (and for grapes, of course), roses can be grown in partial shade, especially during hot summer days, when some shade is actually beneficial to roses.
Both plants prefer southern positions, protected from strong wind.
Some rose and grape vine varieties are very hardy and can tolerate very low temperatures - check with your local garden center which varieties are recommended in your area.
Bare Soil, Mulch or Grass
Many gardeners wonder should they leave the top soil bare, add mulch or grow grass.
Personally, for elevated surfaces, I prefer bare soil or mulch, and for all other areas, I prefer grass.
Bare soil - water loss is the greatest, but any weed or debris is clearly visible and can be removed right away. Also, digging in the fertilizers or compost/humus can be done within seconds. Note that regular tilling/hoeing decrease the water loss.
Mulch - mulch prevent water loss, especially during hot summer days. Also, mulch prevents (up to the point) weeds and as mulch decomposes, it feeds the plants. However, if you want to add some, for example, NPK fertilizer, you have to remove the mulch, spread and dig in the NPK fertilizer and then again cover the soil with mulch.
Grass - growing grass around roses and grape vines (or other plants) makes the garden very decorative, but grass requires water and nutrients, too. But, grass can be mowed with lawn mowers quickly and easily, just be careful when mowing right next to the roses and grape vines. When growing grass in the shades of the grape vines, keep in mind that amount of direct sunlight is lower, so choose the grass mix accordingly. Also, regular watering of the grass, can lead to elevated moisture around the leaves and increased danger of some diseases.
Personally - some of my grape vines are 10 feet (~3m) above the grass, with plenty of air circulating between the grape vines and the grass - I have never noticed any additional problems with diseases on such high grape vine's leaves and grapes.
Pests and Diseases
For a long time, roses were used as alarm to prevent problems with grape vines.
These days, commercial grape vine growers plant roses purely for decorative purposes - just like small gardeners.
Most common diseases are various types of mildews. There are two main kinds of mildews:
- Powdery mildew (Oidium) - Oidium likes a warm and shady environment and does not require a damp conditions.
- Downy mildew - unlike Oidium, Downy mildew likes damp conditions.
They both develops on various parts of the plants, preventing photosynthesis, destroying fruits etc.
Both roses and grape vines should be treated with the mixture of sulfur and copper compounds - just spray the mixture evenly all over the plants, leaving no surface unsprayed.
Note: when using such chemicals, be sure to read and understand the instructions fully.
Pests' infestations should be treated using organic mixtures - they are less toxic (if at all) to plants and to humans and pets and they do their job well.
In order to prevent pests and diseases, keep your roses and grape vines healthy and strong and if possible, grow few more plants next to them, like hyssop (Hyssopus), basil (Ocimum basilicum), oregano (Origanum vulgare), chives (Allium schoenoprasum) etc.
These plants keep insects away by producing repelling scents and can be very beneficial in the whole garden, not only next to roses and grape vines. They are also very decorative plants, too.