Propagating Plants in a Home Nursery - Part 4

I’ve been gardening for a very long time; always growing something; even if  its just a few summer veggies, flowers and herbs, houseplants, or natives for my two acre ‘Home Ground’ habitat garden. As any dedicated gardener will tell you, propagating at least some of the plants you’re using is an integral part of any ‘real’ garden; and so is having a ‘home nursery or hold area’.

Dedicated gardeners almost can’t help themselves; there are just too many good opportunities for propagation once you start to see plants with a ‘propagators eye’. Every established plant in your garden becomes a potential ‘mother plant’, seeds are begging to be collected, and volunteer seedlings absolutely need to be potted up and shared with other gardeners!

I like to joke about being a ‘compulsive propagator’!

Even on a small scale it really makes sense to have systems already set up; these systems don’t have to be elaborate, especially when growing primarily California native plants. A heated greenhouse is not necessary, though some sort of protected environment for starting seeds and cuttings is. This can be as simple as a plastic covered structure with an easy, reliable way to water.

One simple way to make a ’greenhouse’ or ‘shade house’ is with rebar stakes set in the ground, PVC pipes set onto the rebar stakes and bent over to the height and width you want, and plastic or shade cloth zip-tied into place on the PVC pipes. The PVC also provides a place to attach irrigation lines and sprinkler heads.

In my current home nursery set-up we re-purposed an old metal awning frame. Since I wanted to use it primarily for starting seeds and cuttings I had a table frame built. The legs are metal, the table surface is heavy-duty  metal screen; the awning frame has a misting system attached to it and then the whole thing is covered with heavy plastic sheeting, which I can open or close.  I have the misting system set on an irrigation timer to be on three times a day for a minute or two each time, depending on the season. 

I did go to some trouble and minor expense to make this ‘greenhouse bench’  rodent-proof; rats, mice and voles all eat young seedlings (even poisonous Milkweeds!) and once a small plant has been nipped off at the main stem, there is very little hope of  recovery. 

Wherever you have a quantity of plants growing on in pots it’s very important to use a ground cover fabric. It’s also a good idea to avoid over-crowding potted plants; leaving space between pots allows for good air circulation, and allows plants to grow to a good shape and natural form.

There are simple irrigation systems for potted plants; Robert’s Spot Spitters are ‘irrigation heads’ designed for individual containers and each spot-spitter has an on/off position.

A good shady and comfortable place to work with seedlings is pretty important, and having potting soil and other growing mediums, and extra pots on hand is also important. Good sanitation is really important; don’t let your plants become weed or liverwort infested; don’t let a lot of loose leaves or plant materials accumulate around your nursery plants; and don’t let pots stand in puddles.

None of it needs to be expensive; much of what is needed can be recycled or re-purposed! Most of the nursery containers you’ll want can be recycled and passed along from gardener to gardener.

I’ve listed some books below which offer lots of tips and ideas on setting up small scale home nursery systems; and it never hurts to see how other people do it! Visit small nurseries, especially when they are actually propagating plants on site, for more ideas.

  • Plant Propagation; American Horticultural Society (DK Publishing 1999)
  • Making More Plants; The Science, Art and Joy of Propagation, by Ken Druse (Clarkson/Potter Publishers 2000)
  • Propagation Handbook; Basic Techniques for Gardeners, by Geoff Bryant (Stackpole Books 1995)
  • Secrets of Plant Propagation, by Lewis Hill (Storey Publishing 1985)
  • Creative Propagation by Peter Thompson (Timber Press 2005)

CONTAINERS AND OTHER PROPAGATION EQUIPMENT

Containers should be at least 2 inches deep. If you are re-using containers,

such as seed flats, six-pacs, or 4 inch pots, be sure to clean and sterilize them. I soak them first in fresh water to get rid of any residual soil, and then brush them clean in a mild solution of household bleach. The final rinse is in  fresh water; then I let them dry thoroughly, and store them in a large closed container.

Many home propagators will try to grow plants on in a variety of re-purposed food-type containers, such as old yogurt cups. The one very real drawback to this is that an assortment of containers of varying shapes and sizes actually take up more space, and make even application of water much less assured.

Peat pots are often promoted for plants that are sensitive to root disturbance; in theory the whole plant and pot can simply be planted into the garden. Peat pots are best placed in a water-tight tray, and watered from below in a ‘bog’ type fashion. Care has to be taken when planting a peat pot in the garden; be sure to break down the top of the pot, and open it up along the bottom and sides. Make sure that the rim of the peat pot is below the soil level, otherwise it will wick away the moisture from the plant.

When transplanting always choose the smallest container that comfortably fits the plant. I’ll often use a 2” pot, which is also about 2” deep, for the first seedling stage. The seedlings are very delicate, and small pots like these can dry out very quickly; so I’ll set these small pots up on a capillary mat, which maintains moisture that the tiny plants can draw upon.

Not all seeds need light to germinate, but all seedlings need light to grow well; and light from directly overhead is the best. Fluorescent shop lights are fine, a gro-light set-up is even better. You will want to be able to adjust the distance that the light hangs above your containers. To germinate seeds, put the lights about two inches above the container.  When the seeds have germinated, lift the lights to make sure that tender young leaves are not being burned.

Put your lights on a timer; seedlings need fourteen to sixteen hours of light daily. A fan can also be set up to blow gently over the seedlings; plug this into the  timer as well. Circulating air inhibits mold growth, and reduces the chance of damping-off, a fungal disease that rots the seedling stems. The breeze toughens stems, but this can also be accomplished by gently brushing over the tops of your seedlings by hand.

It is important to keep the growing medium moist for good germination, and once germination has occured, the new seedling must not be allowed to dry out. Seedlings are extremely vulnerable at this stage. Plastic lids designed to fit tightly over the seed tray can be used to help maintain good moisture levels. Plastic food wrap also seals in moisture, and warmth; but prop up the plastic wrap on little sticks to make sure that it doesn’t rest on the soil. Undyed burlap can be laid right on the soil surface to keep it moist and dark for species that germinate in the dark. Be sure to check on the seeds daily; as soon as you notice the first green shoots, remove the covering. Water with a very light mist sprayer, or a hand held bottle sprayer. Always water seedlings with water that is at room temperature !

A propagation, or heat mat, is helpful for plants that usually germinate in warm weather, and can give you a head start on the season for summer vegetables and flowers. The propagation mat will bring the soil temperature up to about seventy degrees, which will speed up germination and root growth. Do not, however, place the seedling flats or  pots directly on the mat; raise them above it about one inch, using a baker’s rack or 1”x 1” stakes; otherwise you will be “cooking”  the root system !  

SOIL MIXES AND COMPONENTS

If you plan to propagate on a regular basis, it will make sense to keep the basic components for a variety of soil and cutting mixes on hand. Components are either organic - peat, coir, sphagnum, compost, humus, and vermicompost - or mineral - perlite, vermiculite, pumice, lava rock and sand.

  • Peat Moss or Coir Fiber - adds moisture retention qualities
  • Sphagnum moss - is believed to have a natural sterility that slows or stops certain plant diseases
  • Perlite - has no nutrient value, but makes the mix lighter, and helps to ensure good drainage
  • Vermiculite - has some available minerals, retains some water, and also lightens up the mix and aids with drainage
  • Small Lava Rock – sometimes available in either a 5/16 “ size with ‘lava sand’ or a 3/8” size for landscape or use in larger containers  - either one is an aid in drainage
  • Pumice – aids in drainage
  • Coarse River Sand -  sand promotes really fast drainage (never use playbox or beach sand, which contain salts)
  • Good Quality Organic Soil with a high humus content –
  • Vermicompost - great in the seedling mixes - you can raise your own Red Wigglers for their castings - or purchase it

Soil medium especially formulated for seeds can be purchased, or you can make your own. Commercial mixes are usually soil-less mixtures of peat moss, perlite and vermiculite. Finely screened compost, or vermicompost can be added to this mix to provide nutrients for seedlings.

Vermicompost  is particularly good for seedlings because it is very high in organic phosphorous, which is essential for vigorous root growth. A quarter to a third of the total mix should be compost or vermicompost.

If you are using a soil-less mix, then you will need to fertilize the seedlings after the second set of true leaves is evident. Fish or seaweed fertilizer is fine for tender seedlings; but dilute it to half the strength recommended on the label.

Also; keep in mind (and this all depends on where you live and what your grow systems are set up) that smelly fertilizers will attract the ‘great re-organizers’; raccoons! In my nursery they visit once in a while to hunt for tree frogs amongst my dozens of plants in small pots. With their almost opposable thumbs they can actually lift and toss aside 4 “ containers as they search through the flats for the tiny frogs that hide out underneath. I like raccoons, but I love the treefrogs; so a visit upsets me for more reasons than just disturbing the plants, and I avoid using anything that is overly attractive to these clever and resourceful creatures.

When you have all these soil components on hand you can experiment with different mixes; I’ve listed some that I like below.

  • For a seed starting mix - equal parts of peat moss, fine perlite, vermiculite, and vermicompost.
  • For 2” pots - two parts of soil or compost, and one part each of perliteand peat moss
  • For 4” pots - and for moisture-loving plants - three parts soil, one part each of peat moss, vermiculite, and lava rock –
  • For 4” pots – and for dry-loving plants – three parts soil, one part each perlite and lava rock
  • For 1 gallon pots - three parts soil, one part each of perlite or vermiculite, and pumice or lava rock
  • For species that need a drier, really well-draining mix - add one part coarse river sand