Starting Spring Herb Plants

The Growers Exchange greenhouse staff is busy starting all the herb plants needed for our customer’s gardens this spring. Different plants are started by 3 different methods. Annual, biennial, and some perennial are easy to grow from seed. Basil, cilantro, arugala are examples of some herbs that grow quickly from seed. Italian parsley is slow, up to 3 weeks to germinate and another 4 weeks to grow to transplant size. This herb takes a long time grow from a seed, but there is no other way to obtain new plants. Anise Hyssop, Catnip, and Bergamot are examples of perennial herb plants that may take several weeks to germinate, but are still considered easy to grow from seed. A germination chamber is used to force seeds to sprout before their designated time; parsley goes from 21 to 5 days in the chamber. Seed flats must be taken out immediately after germination, as seedlings quickly die in the high humidity. Technically germination begins with the emergence of the radical. This is the first little white shoot tip to penetrate the seed shell, then germination is over and seedling growth begins. It doesn’t sound like much, if you think about it; emergence of the radical is one of the magic moments in nature. No one can fully explain or replicate a hard little thing that turns into a plant when water is added. Sowing seeds does leave the mind time to wander. And wonder!

Herbs that grow as a shrub, such as rosemary, lavender, and germander could be grown from seed, but would not produce a transplant for 1 or 2 years. To avoid the long seedling stage, Stem cuttings are kept under mist and have a heat source below keeping the root zone warm. The stems soon grow roots and a miniature version of the parent plant is soon ready to transplant. Other herbs such as Costmary defy these methods. Bible leaf plants grow from a rhizome which is divided into new plants by cutting a piece of root with a leaf bud. These divisions also grow a clone of the parent plant.

All these herb plants are on a schedule with someone’s garden. We time our plants to be ready for their new home early this spring.

Growing Herb Plants in Winter

We get many calls from people concerned about the foliage of their herb plants. Each herb is different as has different growing requirements and characteristics. Overall, it is safe to say almost all herb plants prefer full sun all day long as well drained soil. Meeting these two basic requirements will eliminate most problems growing herb plants.

The amount of sun needed for growth cannot be met in a window during winter months. The declining number of daylight each day signals that it is time for the plant to go dormant. Each plant has its own type of dormancy. Some die back to the ground and have no green showing at all until spring.

Lemon Balm, mints, and lovage are examples of herb plants that die to the ground in winter. Shrubby plants like rosemary, lavender, sage and thymes are green in winter, but growth is stopped until spring. Leafy plants such as parsley and cutting celery must be grown large enough before fall to sustain winter cutting. Keeping herbs in a sunny window in winter keeps them close by for cutting as needed; make sure to have enough plants to last until spring.

Watering herb plants is simple. Water your herbs as little as possible. Wet soil will cause root rotting fungus to grow; never let herb plants stand in a saucer of water; water logging will drown the roots. When the soil is dry all the way to the bottom; water sparingly – just enough to dampen the soil.

Propagating Sweet Grass

Sweet grass (Hierochloe odorata) is a Native American grass used in prayer and purifying ceremonies. It is one of the four herbs sacred to Native Americans. Growing Sweet Grass is not difficult once you have a plant, but obtaining that first plant can be difficult. The seed does not store well, or maybe not at all. Purchased seeds come many times with a guarantee of only ten percent germination. From my experience purchasing Sweet grass seed, zero germination is more accurate.

If you have a Sweet Grass plant that is thriving, there are two ways to increase your number of plants. The easiest way is to sow fresh seeds harvested from your plant. I keep an open flat of potting soil next to potted sweet grass. As seeds mature and turn brown, I gently cut the stalk and then strip it of seeds over the soil. Spread the seeds evenly over the surface and gently water. Sometimes the stem holding the seed is still green, but make sure the seeds are completely brown before harvesting. Germination will begin in one to two weeks; allow the seedlings to grow a few inches before transplanting to pots. The seeds ripen over time, so you may have to leave the flat with the plants and harvest ripe seeds as they mature.

Division is the next best way to obtain more sweet grass plants. This is best done in fall or winter to plants that are dormant. Sweet grass spreads in clumps with rhizomes. These shoots can be separated from the mother plant once they have formed new roots. To protect the mother plant, remove side shoots and leave the main clump together. This method can only produce a few new plants at a time and requires some plant skills The fresh seeds of Sweet Grass germinate readily and the plants produce plenty of seed, so this is the easiest method to increase Sweet Grass.

Over Wintering Your Herbs

I am published in Fine Gardening magazine…

It all started with questions I was getting from customers about growing outdoor herbs in the winter. Because we strive to provide an exchange of information for all types of growers, I was more than happy to help. Fine Gardening was getting the same questions from their readers that we were getting from our customers, so they picked up my article and used it in their December 2012 edition to help reach more growers who were having the same questions.


A Strategy for Maintaining Fresh Herbs in Winter

Here are a few tips to help you winter over your favorite herbs:

3 reasons to bring your herbs indoors:

  1. Keep the herbs alive to get more months of enjoyment
  2. Enjoy fresh flavor for all of your hearty winter dishes.
  3. To keep tender plants over-winter for spring planting

When to bring herbs indoors: Two weeks before the first hard frost, typically mid-Sept to mid-October


How to repot:

  • Choose the healthiest plants and compost the others.
  • Clean soil of debris and weeds
  • Dig plants carefully, saving a generous root ball.
  • Repot into containers 2” wider and deeper than the root ball using fresh potting soil
  • Thoroughly water newly potted plants
  • Leave plants outside for a few days to acclimate to their new containers.

Indoor Care Tips:

  • Choose a sunny location with 6-8 hours of direct sun.
  • Consider temperature and humidity. Don’t place them where they will dry out quickly or be in a cold, drafty spot.
  • Typically herbs don’t need a lot of water. Check soil by sticking your finger about a half inch in to test for moisture.
  • Room temp should not go below 50 degrees
  • Let the plants rest before harvesting
  • Don’t be alarmed if your herb plants lose their lower leaves as this is the plant’s way of dealing with the change and getting rid of leaves that no longer produce enough food. Lemon Verbena is especially likely to do this.

Which herbs will work best indoors?

  • Tender perennials: Bay, Lemon Verbena, Lemon Grass
  • Biennial herbs: parsley
  • Annual herbs: cilantro, arugula,

Dormancy requirements make some plants better choices.

  • Unless you want to add grow lights, avoid plants that go dormant like mint
  • Hardy perennials are best left outdoors. Rosemary, Lavender, Mint

6 plants to keep for winter then return to garden in spring:

6 plants that are used for extended harvest.

Replanting your herbs for Spring:

After the last frost, usually late April or early May, start placing potted herbs outside during the day so they get accustomed to a new climate. Keep an eye on night temperatures. Begin to leave them out when night temperatures are above 50F.

  • Plants should have been pruned in winter. Trim stray stems to keep plants bushy
  • Replant in mid-May








Growing White Sage

There is nothing easy about growing white sage; beginning with its seeds.  White sage seeds are tested to a germination rate of twenty percent. Seed with this low of a germination rate are considered too old to use! Being a desert plant, white sage seeds will germinate in a few weeks or 80% will wait for six months to a year, maybe many years. This adaptation insures some white sage seeds will be ready for the next rain, even if ten years away!

This survival strategy is great for the desert, but makes germination uncertain in a greenhouse.  Our cell trays are not a help, because we end up with dead cells or ones with too many seedlings. To insure a strong crop of white sage for the spring 2013 season, we resorted to an old fashion method of sowing seed.  This means each and every seedling must be carefully transplanted to a cell. Being a species plant, there is wide variation in seedling size.

We carefully plant like sizes together.  Watering is always the issue with white sage, well drained potting soil or garden soil with sand added are necessary. Wet soil can cause root rot quickly, never let white sage stay in wet soil!


A Good Seed is Hard to Find

Growing herb plants presents many challenges. Almost all are species plants and have their own requirements for germination, growth, and peaceful establishment in someone’s garden. When The Growers Exchange decided to grow only herb plants, we quickly found ourselves pretty much all alone in our commercial greenhouse community. When growing more common plants, we could always call around and find extra plants when needed.

  Not so with many herb plants! Finding fresh seed for basil, cilantro, parsley, and all the popular culinary herbs is easy. But if we run out of plants, our neighboring greenhouses will be full with geraniums and other flowering plants. If we run out, then we are out! But this inconvenience is small compared to consistently finding seeds for the less known herbs such as White Sage and Holy Basil. Only a few seed companies sell rare herb seeds. Once certain seeds have been located, they must also be viable. Meaning they must be fresh enough to germinate.
  Finding fresh seed for rare herbs is always chancy, and we watch closely to see that we can try again if a batch fails to germinate. To even the odds that we sow fresh viable seed, we have grown our own herb plants in a garden next to the farm office. Seeds are harvested and dried in an old smokehouse. We still must buy seeds, but we also have the seeds we grew, which are very fresh. This doesn’t solve all the problems, but helps plenty and gives us a proactive way to keep a fresh supply of seeds.