Red Rubin basil brings purple foliage to a sunny herb bed while remaining useful in the kitchen. Start it in warmth, give plants room and judge health by growth as well as color. The darkest leaves are not a reason to ignore the usual basil needs for water, drainage and regular harvest.
Planting at a glance
- Crop
- Red Rubin basil
- Life cycle
- Frost-tender annual in most U.S. gardens
- Sowing depth
- ¼ inch
- Germination
- 7–14 days in favorable conditions
- Spacing
- 12–18 inches
- Harvest estimate
- About 65–75 days, conditions permitting
Use local frost dates and growing conditions to adjust planting and harvest timing.
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Know your Red Rubin basil
Red Rubin is a purple-leaved basil selection, grown for culinary use and foliage color. It is distinct from the separately named Dark Opal packet. Both belong in the purple basil group, but they should not be treated as identical cultivars.
Keep young plants labeled, especially when growing several purple basil varieties. Leaf color varies with growth and conditions, so not every leaf will have exactly the same purple intensity. Give the plant room to branch and evaluate the healthy new growth as it develops.
Plan the planting around your harvest
A sunny position makes the purple foliage easy to appreciate against green herbs. Leave enough space that surrounding plants do not shade it as summer growth fills the bed. In a decorative container, pair it only with plants whose water and light needs are compatible, or use a pot of its own.
If you want the plant to remain an attractive specimen, take smaller harvests from several shoots. A major cutting may be useful for the kitchen but temporarily changes its appearance. A second plant lets you separate those goals.
Our basil harvesting guide shows how to choose the next cut while leaving room for regrowth.
Sow in warmth and provide early light
Start seeds indoors about four to six weeks before the date you expect to plant outside. In a short season, an earlier protected start can help, but avoid raising large root-bound plants long before warm weather arrives. Direct sowing is also possible after frost danger has passed and soil has warmed.
Sow about a quarter inch deep in clean seed-starting mix, keep evenly moist and provide warmth around 70–75°F. Once seedlings appear, remove any cover and give bright light. Thin extras so each young plant has room. Cold, wet mix is a poor substitute for a warm seed-starting position.
Transplant and keep roots growing steadily
Harden indoor seedlings gradually for about a week, then plant at their original depth in well-drained soil. Wait for reliably warm conditions, not just a date on the calendar. Basil is sensitive to cold even without a hard freeze. Choose a position with roughly six to eight hours of sun and room for air movement.
Check below the soil surface before watering. Keep the root zone evenly moist but not waterlogged, and aim water at the soil. Use a soil test to guide bed amendments. Containers may need modest feeding according to their mix and fertilizer labels, but extra fertilizer cannot compensate for weak light or damaged roots.
Harvest for the next flush of leaves
Once the plant has several pairs of true leaves and is growing well, cut a shoot above a leaf pair. Leave plenty of healthy, functioning foliage below the cut. New shoots need time to develop before the next heavy cut.
Red Rubin can be used fresh as a colored garnish or in basil dishes, with flavor judged to your taste. Cooking and preservation can change the appearance of purple leaves, so do not expect a pesto or dried herb to keep the exact fresh color. Try a small batch first if presentation matters.
Read the leaves and stems
Some greener leaves or variation in purple intensity do not by themselves identify a disease. Check light, the age of the leaf and whether the whole shoot differs. If a seedling is consistently an unwanted green off-type, you can remove it while preserving the plants you prefer.
Purple basil is not automatically immune to downy mildew. Look for abnormal yellowing, collapse or downy growth on leaf undersides. Improve airflow and remove confirmed diseased plants. Fertilizer will not correct a pathogen problem or turn every variable leaf into a uniform color.
Grow a useful container plant
For a patio plant, choose a pot with drainage holes and enough volume to avoid constant drying. A container about twelve inches across is a useful starting point for one regularly harvested plant, with a larger pot for a bigger specimen. Use potting mix and allow runoff to drain freely.
Indoors, supply strong light rather than relying on a dim windowsill. Start new plants when older ones become woody or decline. Before autumn cold arrives, take the useful harvest and decide whether a new indoor sowing under lights fits your space. A warm room alone will not keep an annual basil productive forever.
Our guide to growing herbs indoors with lights explains how to plan an indoor growing space.
Growing questions
Can I eat Red Rubin basil?
Yes, it is a culinary basil. Use healthy leaves from correctly identified plants and taste before substituting it in a recipe.
Is Red Rubin the same as Dark Opal?
No. They are separately named purple basil selections.
Why are some leaves greener?
Color can vary with plant genetics and growing conditions. Check light and overall health before treating it as a deficiency.
Ready for another planting? See Red Rubin Basil Seeds for the current packet options.
Sources and photo credits
Prepared with AI assistance using Gardeners Basics product information and horticultural references. This guide does not describe a Gardeners Basics growing trial. Research and license links open in a new tab.
Growing references
- Penn State: Basil.
- University of Minnesota: Growing Basil.
- University of Minnesota: Basil downy mildew.
Photo credits
Photographs illustrate the crop or growing stage. They are not photographs of a Gardeners Basics growing trial; a specific cultivar is identified only where the source documents it.
- Cover: Purple Basil.jpg, Megalibrarygirl. CC BY-SA 3.0. Resized for display. The Pinterest graphic crops the cover photograph; its photo retains the stated license.
- Article photo 1: -2020-07-10 Purple basil (Ocimum basilicum) seedlings, Trimingham.JPG, Kolforn ( Kolforn ) I'd appreciate if you could mail me (Kolforn@gmail.com) if you want to use this picture out of the Wikimedia project scope. This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. You are free: to share – to copy, distribute and transmit the work to remix – to adapt the work Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original. https://creativecommons.org/licenses/by-sa/4.0 CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 true true. CC BY-SA 4.0. Resized for display. The Pinterest graphic crops the cover photograph; its photo retains the stated license.
