Thursday, October 03, 2013

Over-Wintering Herbs

1. Look for the most healthy plants to over-winter.
 
2. Rid your plants of insects and disease before bringing them in. Use Insecticidal soap or any organic product.  Make sure it is safe to use on edibles.  Isolate your plants for about 2 weeks from other houseplants before introducing them into the house to avoid spreading any insects and disease.
 
3. The best chance for success with some of the culinary herbs indoors for the winter is to start new plants from seed.  The best time to start seed is early August for herbs such as basil, chives, coriander, dill, parsley, marjoram, rosemary, sage, summer savory and thyme.  Plant in 4 inch pots using a medium of soil, sand, peat and perlite. Sink the pots into the garden up to their necks. Cover the seeds with sand or sphagnum moss.  Keep moist and fertilize with a liquid seaweed or a fish emulsion (Organique) when the sprouts are 3 inches high.  If you’ve missed the August sowing, start them any time indoors.
 
4. Other culinary herbs for indoors such as mint, oregano and French tarragon are best prepared by potting up root divisions after the harvest.  The optimum time to dig up the plants that you want to keep indoors is about a month before the first fall frost.  Bring in existing plants or make new ones by dividing them.  Capture as many of the roots as you can.  Mature plants, such as sweet marjoram, lavender and scented geraniums should be cut back by about 1/3 their full height to make them more manageable.  (You can cut them back even more drastically if the root ball is small.)  Put each one into a pot that is slightly larger than its roots.  Mint needs a lot of room so consider planting some in hanging baskets.  Fill in with a soil less growing mix.  Let the plants get settled in the pots in a lightly shaded outdoor location for a week or so.  Then move them into deeper shade for a week to get them ready to come indoors. Before frost arrives, bring tender herbs indoors to the window or light garden you’ve prepared.  
 
5. Let chives and garlic chives stay out through a month or so of cold before you bring them indoors.  They will grow much better indoors if they get a short winter to trick them into thinking it’s spring.  If conditions are right, they will re-sprout and provide you with some fragrant foliage to harvest in midwinter. 
 
6. Spearmint and tarragon will lose some leaves, but will perk up by February.  Keep them cool and dry until they re-sprout.  You can then begin to water and fertilize lightly every couple of weeks.
 
7. Other herbs to consider for inside gardening are aloe, bay tree, catnip, lavender, scented geraniums and lemon verbena.
 
8. When your herbs are grouped together indoors, they may be more susceptible to pest problems.  If you find whiteflies fluttering around the indoor herb garden, spray with Insecticidal soap or another organic product to kill mature flies and repeat until you get rid of newly hatched generations.
 
9. Red spider mites may attack because the humidity is low.  If so, use a pebble tray and fight them with insecticidal soap (Pebbles allow you to rest herb plants over – not in a tray of water.)  Avoid misting your plants to increase humidity as this will encourage insects and disease.  To discourage disease, remove dark, dead and sickly growth, and scrub your pruning shears or knife in a solution of 1 part bleach to 10 parts water between each cut.
 
10. The key to successfully growing herbs indoors is bright light.  A large window facing south is best, with an eastern exposure the next choice.  Bay, lemon balm and the other mints need only partial sun indoors and can be in east of west-facing windows.  If you cannot provide the necessary light but want herbs, consider investing in a grow-light unit.  This may be a simple fluorescent work light with 4 foot tubes, one warm and one cool-white, or two full-spectrum bulbs.  To be effective, fluorescent lights should be lit for at least 15 to 16 hours per day.
 
11. Most herbs need cool temperatures – in the 15 – 20 degree Celsius range during the day and cooler at night.  As well, good air circulation is important to reduce problems with fungus diseases.  Make sure air flows freely around the plants, but don’t put them in front of a heating vent.  It’s too hot and dry there.  Instead, invest in a small fan to gently keep the air moving.
 
12. Adjust the amount you fertilize to your light levels.  In a dark area where herbs struggle to stay alive, they may not need fertilizer at all.  In bright light where herbs are actively growing, you can fertilize every month.  Be sure to harvest fast-growing herbs often so they’ll stay compact.  You may want to replant crops that you use often so you will always have a fresh young plant to take the place of an older one.
 
13. You must also pay a bit more attention to the water and nutrient needs of your indoor plants.  Different herbs need different quantities of water when grown indoors.  Basil, parsley, mint, chervil and arugula do best if kept moist, not bone dry or soggy wet.  Let Mediterranean plants such as rosemary and lavender dry out slightly before you water again.  Too much water has probably killed more container-grown herbs than too little.  The plants shouldn’t sit in water, but instead, the water should evaporate up around them.  Because most of our homes are dry during the winter, increase the humidity around the plants by using a room or whole-house humidifier.  Alternatively, set the herbs on either commercially available trays that hold water and have raised racks for holding the pots, or on trays filled with pebbles.
 
14. When you wish spring would hurry up, spend some time nurturing your sage or lavender. 
Here is a list of plants that can thrive indoors, with recommended means of propagation.  This chart was compiled by Susan McClure and appears in her book The Herb Gardener:  A Guide for All Seasons.
 
Sow Seed Take Cuttings
 
Arugula Basil
Basil Mint
Chervil Oregano
Coriander/cilantr Pineapple sage
Dill         Rosemary
Mustard Sage
Parsley Scented Geraniums
Summer Savory Thyme
Sweet Marjoram
 
Bring in Mature Plants
 
Chives         Garlic Chives
Greek Oregano Lavender
Lemon Verbena Mint
Rosemary Sage
Scented Geraniums Summer Savory
Sweet Bay Sweet Marjoram
Thyme
 
 
Arlene Ortiz (Wheeler)
Posted by Tammy Jensen at 6:29 PM