by Karyn Ames
New Mexico Certified Nursery Professional
Last week’s article on seed-starting generated queries from folks during the week. So, let’s flesh out the seed-starting information with answers to some frequently asked questions (FAQs).
Question: How do you know when to start your seeds? You gave actual dates, but I’d like to understand how you came up with those dates.
Answer: Every plant has a number of days until germination and a size it will be on a particular date. For instance, tomatoes take 7 to 14 days to germinate at 75 degrees F. If I want to transplant them from the 6-pack stage, I need to plant them 6 to 8 weeks before I put them in the garden or in barrels on the patio. If I want a larger plant in a 4-inch pot, I need 8 to 10 weeks. Although I start my tomatoes in 6-packs, I plant them up into increasingly larger pots. So, when I put my tomatoes in the garden the first week in June, I have allowed 12 weeks from seed-starting to final planting.
Q: Where do you get germination information?
A: Johnny’s Selected Seeds is an excellent resource for growers. However, most seed catalogs do not provide detailed starting and growing information. Because I grew for my own commercial greenhouse, I gleaned information over the years. Now you can get that information from the Internet.
Q: I noticed that my seed-starting soil mix floats and does not take up water easily. What can I do?
A: Fill your cell packs with the soil mix and rest the packs in a sink filled with tepid water up to just below the container tops. Through osmosis, the soil will take up water from the bottom and become thoroughly saturated. Then you can plant your seeds on top of the soil.
Q: Do I need to add fertilizer to my seed-starting soil mix?
A: No. Many mixes come with some fertilizer in them, but even if they don’t, seedlings do not need fertilizer until their first true leaves appear. The first green leaf you see upon germination is the cotyledon, which is part of the embryo of the seed. Cotyledons contain stored food reserves for the seedlings.
Q: Could you give some seed-starting dates for flowers?
A: When you consider that you can get a large selection of petunias, pansies, and impatiens from the store, you might want to save your precious growing space for your favorites or plants you cannot find at garden centers.
See the table for starting some annual flowers. I show the number of weeks the seedlings need in 4- or 6-cell packs before transplanting into the garden. (I plant seeds directly into cell packs.)