Our New Greenhouse Project: Bottom Heat

The Delta-T heating system we purchased will deliver heat where it matters most to plant development, the root zone. Everyone knows that a healthy plant must have a healthy root system. To insure all Growers Exchange herb plants fill their pot with vigorous roots, we will keep soil temperatures at 65 degrees to stimulate rapid root development.

To keep the green plant tops from growing too quickly, the air temperature in the greenhouse will be at 50 degrees at night. Growth is slower at cooler temperatures so the stems are thicker and stronger. The stem length between nodes is shortened, creating a symmetrical plant.

Bottom heat will also allow us to propagate more plants from cuttings. Many herbs like rosemary, lavender, and mint are best increased by vegetative propagation, also known as cloning. A mist system keeps the non-rooted plant stems hydrated until the warm soil promotes root growth. In about a month a new plant is ready to be re-potted.

Tropical herb plants like Lemon Verbena, Lemon GrassVietnamese Coriander, Dill, and Basil will also benefit from the new bottom heat. Try as we do, some days we can only keep the greenhouse but so warm. Wood fired space heaters warm the greenhouse air; but some winter days only so much heat is possible. Now we will be able to keep the root zone of these tropical herbs at their desired 65 degrees no matter what is happening outside.

As greenhouse growers, this new bottom heat is as exciting as Christmas! We will have plenty of herb plants ready for spring planting. The bottom heat helps the seedlings prepare for Spring. Winter is the best time to plan your herb garden. Don’t forget to order early, many herb plants are grown in limited quantity. And a tip from a greenhouse grower: have plants sent as early as your planting zone allows.

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.

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.

From Seed To Sprout: Our Herb Plants Are Getting Big!


Thyme, Patchouli, Rosemary, Lavender and more! Here’s an inside look at some of our herbs that are big enough to be repotted into their new homes! We’ve been growing our crops for months now, starting from seeds that sprout in our germination chamber, and eventually grow big enough to replant into larger pots. ( If you read our previous blog, “Tis The Season To Plant Seedlings“, you’ll enjoy the before and after pictures of some of our plants! )

They’ll continue growing in our approximately four inch pots until they ship directly to your door! Do you see any plants that you’ve ordered for your spring garden in these pictures? We’ll begin shipping in Mid March, starting with  zones 8-11, so they’ll be arriving before you know it! Wondering when your plants will ship? Click here!

Here’s a close up of our little Patchouli plants. At about two inches tall, they’re ready for to be repotted this week. Such beautiful, green growth! The process of growing plants is still an amazing experience to me. It’s truly a proud moment when you see your finished product, a lush, healthy herb plant, that you’ve known since it was a tiny seed, and you know that it will really make a difference in someone’s home or garden because of the care you’ve given it. We feel like proud papas down in the greenhouse when we begin to ship these little guys!

Tis The Season To Plant Seedlings

While everyone is running around finishing holiday shopping, we’re busier than Santa’s elves in our greenhouse. Introducing a few new techniques and tricks of the trade, we’ve been hard at work planting and preparing our herbs and flowers for their debut this spring. Hand-planted and all grown in our greenhouse, we get to know the different personalities of these plants like old friends. For instance,we know that though aromatic and beautiful, Lavender can be cranky about too much water. Or that Horehound, a medicinal herb and cousin to Mint, is easy going and grows quickly. Knowing our plants from the time they germinate allows us to have the best quality control over what we sell, and we have high standards for our plants because if we wouldn’t want it in our own garden, we won’t ship it. This is the benefit to a family-owned nursery versus a big box store or corporate grower. We care about the plants we grow. Like an anxious, proud papa, I eagerly check the germination chamber constantly each week to see if any “due dates” have arrived early.

Looks like some of the first Betony seeds are beginning to sprout!

Stay posted for more pictures and news on how your favorite herbs and flowers are growing! You can actually watch the progress of your order, from their inception in our greenhouse, to their maturity in your garden. Order these babies now and reserve yours for spring shipping, because the early bird does get the worm!

Companion Plants Are Friends Til the End

Here at The Growers Exchange, we’re excited to say we have officially started our annual employee vegetable garden!  We have started our early spring greens, broccoli, and cabbage, and have added a few herbs to the mix as companion plants.

Broccoli and the entire cabbage family (including cauliflower, kale, kohlrabi, collards, and brussel sprouts) grow wonderfully with aromatic herbs such as dill, chamomile, sage, rosemary, hyssop, and thyme.  All members of the cabbage family are heavy feeders, and will greatly benefit from nearby, healthy, herb plants– plants who will double as insect repellents!  Although the white cabbage butterfly is not harmful and can help pollinate, its pesky caterpillars are the ones who will chomp away at and destroy your crop.  Aromatic herbs will help keep these hungry little guys away.