Category Archives: Propagating & Pruning

propagation & pruning

Seed Collecting Tips

Clockwise from top left: Paeonia obovata, Amsonia hubrictii, Aster laeve, Nicotiana knightiana

The most frequently asked question regarding seed collecting is How do I know if seed is ripe?” Here’s a very general answer, for seeds of different plants ripen at different times, and their appearance, when ripe, can be as different as the individual plants that produced them. You need to keep a watchful eye. Observe the green immature pods over time, and suddenly you’ll notice brown seed capsules ready to split and burst. If you are not vigilant, you may discover empty seed pods days later, and your opportunity will have passed. (You can also try placing a paper bag over the immature seed capsule and securing it with string. When the seed ripens it will be contained in the bag.)

Collecting Tips: Mature seeds are usually dark in color, firm, and dry. Seeds that are green and moist are usually immature and generally will not germinate or will produce unhealthy seedlings. The flesh of pulpy fruits often becomes soft and changes from green/yellow, to red or blue-purple when ripe.

Cleaning: In a cool dry space, place dry seed capsules in a paper bag secured with string and hang upside down.  Clustered seeds of composite plants such as Asters and Marigolds might benefit from being laid out on newspaper layers and allowed to dry more completely. Remove the chaff and other vegetable matter which may harbor fungal spores which will spread and infect the seeds. Moist seed from fleshy fruit such as tomatoes, or from ornamentals such as Arisaema, should have the mucilage (the wet medium surrounding seed) rinsed off. Place the ripened seed in a sieve and rinse off thoroughly. Spread rinsed seed on layers of newspaper and allow to air dry.

Storage: Only store cleaned and dry seed. The combination of moisture and warmth will cause spoilage. Store seed in paper envelopes or bags to allow them to breathe. Don’t use plastic baggies, which may trap moisture. Keep your seeds in a cool dark dry space. Your refrigerator would work, if you have room, or perhaps a closet or cabinet in a cool room. Clearly label all packets with all pertinent information.

Important: Remember the lower the humidity and temperature in storage, the longer the viability of the stored seed

For more info online: http://theseedsite.co.uk/harvesting.html If you really want the specifics, you need the seed germinating bible. Norman Deno’s book Seed Germination, Theory and Practice can be purchased through the North American Rock Garden Society’s Bookstore.

Pruning Hydrangea

Hydrangea paniculata ‘Limelight’ blooms on new growth

Even seasoned gardeners seem to be confused as to when to prune Hydrangea.

Begin by identifying which Hydrangea species you are growing, to determine whether it will bloom on new growth or on old wood (last year’s stalks). The species arborescens, paniculata and some newer forms of macrophylla bloom on new wood. All the Hydrangea macrophylla (Mophead and Lacecap types) and quercifolia (Oakleaf)  bloom on old wood, as long as there isn’t winter damage. Next year?s blossoms are set on the upper portion of the woody stalks in late summer and fall. H. macrophylla selections should not be pruned until after the plants have leafed out. In late spring, prune out or tip back any dead wood for a clean appearance.

The hardiest and most foolproof of all the Hydrangea are the paniculata group (Pee Gee types) and the arborescens group (Smooth Hydrangea). Both of these species can be cut within inches of the ground each spring if you want to control the size of your plants.  They stalks can always be thinned to improve plant shape, and there is no harm to next year’s display if you want to cut long stemmed bouquets in summer and fall.

There are a lot of new Hydrangea macrophylla selections on the market, including ‘Double Expressions’, ‘Red Sensation’, ‘Let’s Dance Starlight’, and ‘Endless Summer’ that bloom on old and new wood. The blossoms appearing on old growth will display in early summer, while the flowers that form on new growth will appear later in August and September, for a long continuous display. If you live in the colder parts of zone 6 or zone 5, you may get too much winterkill for blossoms on the old growth, but you will still be able to enjoy a late summer through fall display.