If you attended the recent Summer Seed Exchange, you probably have seeds or cuttings to plant. Though planting seeds and cuttings may seem simple, a few things can help improve your success rate.
Seeds for most root crops will do best planted directly in the garden. The roots will form and grow better if they are not transplanted. Start by thoroughly working and wetting the soil so that you can avoid disturbing your seeds for a few days. The size of the seed will determine the depth of the planting. Tiny seeds should be planted near the surface with a dusting of vermiculite to help prevent damping off. Larger seeds can be planted deeper, about once or twice the size of the seed deep. Keeping the soil moist will help with germination.
Avoid soaking wet soil which can encourage diseases that can kill your seedlings.
Many other seeds benefit from being planted in seeding trays to germinate and transplanted later. Use clean trays and a sterile seeding mix to ensure that no soil-borne diseases are present. Store the mix in its original container to prevent contamination.
Large seeds, or ones with thick, tough seed coats should be scarified. Simply soaking the seeds overnight before planting can help soften the seed coat and give them a head start. Beans are a good example of seeds that benefit from soaking before planting.
Most other seeds, including lettuces, greens, peppers, tomatoes, eggplant and herbs, do not need soaking and will actually germinate best if they have been harvested when mature and completely dried before planting.
It is often best to thoroughly moisten the soil before planting. Making a muddy mass of seeding mix and pressing it into your seed trays will provide a good starting moisture level. Once seeds are planted and trays labeled, top the tray with vermiculite to reduce the chance of disease. Watering your seedlings with a fine mist of chamomile tea several times a week is another way to prevent disease. Chamomile contains anti-fungal properties that can offset pathogens.
Seeds germinate best in a warm location out of full sun. Patience is required. Some seeds can take several weeks to germinate. Keep your trays in shade with good air circulation and protection from rain. Once seeds germinate and the plants start growing, they’ll need a few hours of sun each day so they don’t get leggy, looking for light.
When seedlings are several inches high and putting out new leaves, put them in larger containers and add a very small amount of low-nitrogen fertilizer until they are strong enough to survive in the garden.
For quick additions of mature plants, take cuttings from existing plants and root them. Note that not all plants will grow from cuttings.
Start with semi-woody or mature stem material. Taking cuttings that are about the diameter of a pencil and about 4 inches long with several nodes is best. With rosemary, lavender or woody basil stems, you may have success with thinner material.
Many edible plants, including tomatoes, peppers, Okinawan spinach, and flowers such as roses, chrysanthemums and carnations can grow from cuttings.
Prepare a damp medium of a vermiculite and perlite mix for your cuttings; remove most of their leaves and dip them in a rooting hormone before placing them in the medium. Keep the medium moist in a cool spot and wait for the cuttings to put out new leaves. Once they start to leaf out, pot them in soil with a little fertilizer and wait for them to get large enough to put in the garden.
Tropical gardening helpline
Raven asks: Why do we have trouble growing white, red, russet and gold potatoes in Kona? My sweet potatoes do well, but every time I grow any variety of white potatoes, the plants get diseased and I only get a few small potatoes.
Answer: Your “small potatoes” are probably caused by a virus that is common in white potato varieties. Many different virus strains exist, but the most common one here is potato virus Y. It is difficult to combat or control because it is vectored by aphids. In climates with cold winters, the vectors die during the winter. In Hawaii these insects are numerous year round and can quickly spread this virus.
PVY also infects other plants in the Solenacea family, especially tomato plants. Aphids are the most efficient and common means of transmission — the virus sticks to their mouths, but it can also be transmitted by machinery, tools and damaging plants while walking through a field.
Once PVY is inside a host plant, it multiplies quickly. It can cause malformed plant tissues including leaf necrosis, mottling, streaking and mosaic, as well as reduced production of tubers. It can also cause leaves to die and tuber necrotic ringspot disease. Infection reduces storage quality of the potato tubers by decreasing mass and increasing shrinkage.
Several strains of the virus have been identified with a variety of symptoms. Mixed infections of several strains are not unusual. Some potato varieties do not show symptoms, but can carry the virus and can serve as reservoirs for aphid transmission. If the leaves of your potato plant are stunted or curled, this may be another virus strain but it is likely transmitted in the same way and will cause similar effects.
Following these guidelines can help control the virus, but in the tropics it is difficult to manage. You might want to consider growing sweet potatoes instead which have far fewer problems here.
c Buy seed potatoes that have been certified virus-free or have reported tolerance or resistance to viruses.
c Remove any potatoes left over from a previous harvest as they may be virus reservoirs.
c Destroy symptomatic plants to eliminate them as sources for virus spread. Also remove weeds which may serve as virus reservoirs.
c Look for aphids regularly and apply products necessary to discourage or kill them. Some pyrethroid aphicides may have these features.
c Sanitize all tools and planters. Avoid reusing soil which could harbor the vectors of some potato viruses.
Go to potatovirus.com for pictures and information about all potato virus strains.
Email plant questions to email@example.com for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.
Diana Duff is an organic farmer, plant adviser and consultant.