Plant Cultural Information – Important Guide for All the Planters

Please check back as we will be posting many useful tips & techniques on growing alpine & rock garden plants.

plant cultural info

Sowing Hints

A good general-purpose sowing media for most alpines can be made by mixing 1 part by volume commercial soil-less growing mix such as Sunshine Mix with 1 part chicken grit (available at feed & pet stores).

Particularly difficult species may benefit from an even coarser mix of 2 parts grit to one growing mix. Fill seedpods to within ¼” of the top, firm just enough to flatten the surface & scatter the seeds evenly.

Larger seeds can then be lightly covered to 2-3 times their thickness with more sowing media, very fine seeds do not need this extra layer.

All pots except those with very fine seeds should then be filled to the rim with a ¼” layer of straight chicken grit. Water from below by standing in a dish filled with warm water.

Once dampness shows on top, pots can be set to drain & placed into a shaded location with a suitable temperature.

Check at regular intervals for germination & make sure pots stay moist as coarse sowing media such as those recommended above dry out quite quickly, especially in warm weather. Pots with very fine seeds may benefit from the poly bag system as described below.

Key to Seedlist Sowing Information

Sow: warm

germinates best at warm temperatures, keep pots inside if sown during winter; if air temperatures are cool use heat tape beneath seedpods to keep them warm.

Sow: cool

germinates best at cool temperatures usually experienced during spring & fall; keep pots outside or on an unheated porch; ideal conditions are cool days with nighttime temperatures just above or below frost.

Sow: outside

germinates best with varying day/night temperatures, keep pots outside (preferably in the light shade) & exposed to natural temperature changes, frost, snow, etc; hard frosts at night with thawing during the day is beneficial; a covering of window screen helps protect seedpods from damage by heavy rain, mice, cats & birds.

Scarify seeds

some species (notably most Pea Family members) have very hard seedcoats and germinate best if the seed is lightly abraded by rubbing between two pieces of fine sandpaper. Alternatively, hard seeds can be lightly chipped or nicked with a razor knife.

Direct Sow

Pea Family members & some others are very sensitive to transplanting damage and usually do better if seeds are sown where the plants are to grow; failing this you may consider sowing into paper or peat pots and transplanting ‘pot ‘n all’ when setting out.


the fungus attacks young seedlings causing stems to rot at the soil line; a common problem with overcrowded seedlings or those grown too warm with too little light; can be overcome to some extent by an application of dilute liquid fungicide such as ‘No-Damp’


Gibberellic Acid, this growth hormone can aid in stimulating the germination of some species – before sowing, the seed is soaked in a solution of about 1000ppm concentration; the seed is then sown as normal, usually in warmth. Ga3 in concentrated form is available from Gardens North, 5984 Third Line Rd, RR # 3, North Gower, Ontario K0A 2T0

Poly bag treatment

seedpods with very tiny seeds can benefit from the extra humidity by enclosing them in a plastic baggie. With this system, the seed is not covered but allowed to rest on top of the damp sowing mix, the humidity in the baggie can’t escape & the bagged pot can be left without further watering until germination has occurred.

Bagged pots must be kept out of direct sunlight or they will quickly overheat & the seed damaged. Starting bagged seed pots under fluorescent lights overcomes this problem & can be very effective.

Pea Family treatment

plants with hard seed coats can have delayed germination, to help overcome this, such seeds can be scarified or chipped as mentioned above.

Alternatively, hard seeds can be soaked overnight in hot water, particularly hard seeds may benefit from a second hot water soak before sowing. After treatment, the seed is sown in the usual manner & the seedpods are kept in warm conditions.

If no germination is evident within a month or two, then move the seed pots outside & allow germination to occur at its own pace.