Starting Seeds presented by Liz Hartman, March 2016 It is in the best interest of a plant to have seeds that will grow readily in the right conditions. Seeds want to grow! All we have to do is give them what they need. Every gardener has their own best tricks for starting seeds. A quick internet search will prove that each of us swears that “our way” is the best. I’m giving you “my way” today, which I based on a whole bunch of research then honed to what works for me over the last few years using trial and error. Why do we start some seeds indoors? What seeds aren’t good for indoor starts? Seeds need ​
warmth​
and ​
water​
to germinate. (Almost everybody germinates a bean seed on a paper towel in a plastic bag in elementary school, right?) Seedlings also need ​
soil​
and ​
light​
. Warmth Seeds that get started indoors usually don’t need light to germinate but for many of them their optimal soil temperature is around 85F! A seedling heat mat, sized to fit under a single standard tray (about 9”x19”) is about $25 and I think it’s well worth the money if you really want good results. All the “Dirt”
It’s important to start seeds in sterile potting mix. Bringing in garden soil potentially also brings in pathogens and it’s rather “heavy” for seedlings to push their tiny sprouts and roots through. “Potting mix” is sold at home improvements stores and garden centers. Notice what is in it and decide what you want in yours. (A product that promises bigger and better plants and and things like trademarked “micro­nutrients” has chemical fertilizers included.) Maxfield’s Potting Soil is an example from a local company that contains only natural components but is more expensive than less “organic” options. Making your own is a great way to know exactly what it contains. My Soilless Potting Mix (adapted from recommendations by Moose, an amazing farmer/gardener) 4 parts coconut coir (or peat moss) *supplies a lightweight medium that retains water, peat raises ecological concerns with its use 3 parts worm castings (or compost) *since I’m going to use the same mix even as I “pot up” (more on that later), the seedlings will need nutrients to grow into plants. This is the natural alternative to chemical fertilizers 1 part perlite *improves drainage 1 part vermiculite *retains moisture 1 To make a large batch, lay a clean tarp on a relatively clean/dry area, dump all the ingredients together and roll it from edge to edge to mix. Store it in bags (potentially the same ones your coir and/or castings came in) inside. Containers Seed starting trays ­ nice because they’re compact and you can buy short or taller covers that fit over them to keep in moisture Repurposing most small disposable containers is possible. I’ve used yogurt and sour cream containers with holes punched in the bottoms and set on a rimmed cookie sheet. The tops from some bakery sheet cakes make great covers to create a mini greenhouse. Good drainage is important when picking a container. Consistently moist but not “wet” is the goal. I’ve lost more seedlings by drowning them than I have to underwatering. Some plants are picky about having their roots disturbed. The most common ones are cucurbits (squash, melons, cucumbers). These can be started directly in soil after last frost but I usually like to give mine just a few weeks’ head start. I start these straight off in 4” pots and only transplant them when they’re going into the garden. This is also an excellent use for peat pots (cut through the sides before directly planting the whole pot) or newspaper “pots” (for an easy tutorial, search to find “Create Newspaper Pots for Seed Starting” at HGTV Gardens’ site) Soil blocks Eggshells and egg cartons are often touted as good options. Their small space allows for so little root growth, I’ve never really seen them as very useful. Crush up your eggshells and put them in your compost or directly into your garden soil though! Light I have never met anyone who had success getting good transplants from only natural light. Seeds will germinate (with a heat mat) and grow but will get “leggy” as they strive to reach more light and will be weak from the effort. As soon as seedlings appear in your tray, put them under a light. I use a timer on mine and leave it on about 12 hours a day. Cheapest option​
­ a simple 4’ fluorescent shop light with four tubes could cost as little as $30. You would need to rig up a way to hang it, ideally so it can be raised (or have the seedlings lowered below it) as the plants grow. If this type of light is farther than a couple inches from the tops of the plants they will still tend toward legginess. If you see lights that take T12 tubes (which are being phased out), avoid them and seek out fixtures for ​
T8s. 2 The “T” number refers to the width of the bulb (T12 = 12/8”= 1 ½”). I’m not an expert on the technology but all growers need to know is that higher number bulbs are older and produce less light. More expensive option​
­ 4’/4 tube ​
T5 fixtures ​
are “grow lights” that are readily available (even at home improvement big box stores) ­ especially in Colorado due to the marijuana industry. They are around $150 new but a great deal might be possible if you’re patient on Craigslist. I justified the expense by calculating what I save each year starting my own transplants instead of buying them. T5s are bright enough that they can be fixed at a point about a foot above your trays from the very beginning and the plants will get enough light. This makes watering and checking on the seedlings much easier and I’m not fussing with the height as the plants grow. My basement set up in mid­April 2014. My tomatoes got so big by planting time (I always plant shortly after Mother’s Day, around May 15) that I now start them a few weeks later. The T5 fixtures are on the wire shelves at the right and my old T8s are on the left. 3 Timing Average last frost in Denver is May 10 ­ 20 (Remember all those snowy Mother’s Days?) Working backwards from May 20… March 25 ­ 8 weeks peppers (hotter pepper = higher ideal soil temp and longer time to germination) *broccoli, cabbage, cauliflower (for planting out 4 weeks before last frost) April 8 ­ 6 weeks tomatoes *basil marigolds April 22 ­ 4 weeks *cucumbers, melons, squash zinnias *can be direct sown Planting out ­ Hardening off is the process of getting the seedlings ready to live outside in the week prior to planting day. ­ On the first day, find a semi­shady spot outside for a couple of hours. On successive days expose the plants to slightly more sun for slightly longer times until the plants spend all day outside. Yellowing can indicate they’re getting stressed and it would be good to slow down the process. ­ Cutting back on watering and letting a fan blow gently on the plants are also ways to get them ready for planting. Ideally, plant out on an overcast day or provide some shade for the new transplants on their first day to allow some recovery time. 4