Starting Seeds IndoorsOne of the most rewarding garden adventures is growing your own vegetables from seed. It’s fun, economical, and can increase your summer garden yields. Here’s the what, when, and how to get you off on the right foot for a fruitful growing season. Some plants fare better when started indoors:
It is important to choose appropriate seeds for your garden. According to the USDA zones map, we are zone 6 (z.6), yet very few z.6 plants survive in Truckee. Depending on the location, we use z.3-4 as a starting point for plants likely to thrive here. Department stores, hardware, and drug stores have pre-selected regional seed racks from suppliers. Experienced local nurseries carefully select each and every variety of seed for growing well in our specific (challenging) environment.Â
For best results, plant seeds in a bagged seed starting mix (seedling medium) in cell-trays, peat-pots, or cow-pots. Do not use common “potting soil” or composts and never use native soil in a container (just don’t). You can also use a sterile plant starting medium like rockwool, oasis, or peat (or coir) pellets. Set the pots or mediums in “10-20” propagation drainage trays.
Trays catch the water you add to your seedlings, whether they are in small individual starting mediums or in containers (pots, or even egg cartons.)
Half paper milk cartons, paper cups, tin cans, new or reused plastic pots can all work as containers IF there are holes in the bottoms. There must be proper drainage to allow water out and fresh air in.
Fill your starter containers with seedling mix, water them thoroughly, several times, and pour out the excess water from the bottom tray. It’s vital that the soil or medium you are planting the seeds in is thoroughly moist prior to planting seeds. Once planted, they should never dry out and never have more than ÂĽ inch of water at the bottom of the tray. Misting seedling soil with a spray bottle is common. pouring water onto your seeds or seedlings can disturb the delicate new roots. Ideally, use luke-warm or room temperature water.Â
Plant sparingly. Seeds should not be planted too close together. Seedlings from dense seeding will be spindly with both weak shoots and roots and will be more difficult to transplant into larger containers.
A dome or clear cover for your seedlings is an easy way to maintain moisture during germination. There are tall and short domes that fit over standard 10-20 trays before the seeds germinate and while seedlings are small. Covering the tray or growing container with a clear plastic bag also works. Be sure to lift the lid, or open the bag, once a day to refresh the air. Once true leaves are formed, remove the dome. An oscillating fan, used a couple of times a day, improves airflow, moves and strengthens the stems, and reduces disease. Be extra vigilant with watering.
Many seeds prefer dark for germination. Sprout the seeds in a warm dark location and then move them to more light when they’ve mostly emerged. Under a shop-light or in an east-facing windowsill are great places for seedling trays. Keep them just out or direct sunlight for a few days. South-facing windows are ideal for growing transplanted tomatoes and peppers up to a good size before moving outdoors.
Depending on what you’re growing, it’s important to sow seeds in soil that is the right temperature for their individual needs. Most seeds prefer warm soil to germinate. If you start them indoors, it’s best to do it on heat-mats. Most seeds sprout best at a temperature of 75-80ÂşF and thrive in that consistent temperature range for two or so weeks after sprouting.Â
Direct mountain sunlight is too intense for indoor seedlings. If you do not have an ideal window, supplemental light works well. The go-to for seedling lighting is inexpensive 4’ LED shop lights. Incandescent lamps are hot and inefficient. Once seeds have sprouted, your seedlings need ~13-16 hours of daily sunlight. For plants with good window light, use supplemental light only at night. Plants under LED shop fixtures and those with only window light can be turned daily so seedlings don’t grow sideways.
Seeds contain all of the energy and nutrients needed for germination (sprouting, emerging) and growing young plants for a week or two. After the second set of true leaves appear, fertilization is recommended. Most seed starting soils will have a mild “nutrient package” of slow release fertilizer. Any diluted organic fertilizer will also be helpful. Seaweed based-fertilizers can stimulate root growth and may aid in disease prevention.Â
If the cells have numerous seedlings, carefully snip-off the excess seedlings with scissors to avoid damaging the keep-plants’ roots. Alternatively, gently separate and transplant individual seedlings to larger containers after they have 1-2 true leaves. Depending on the timing, either plant them directly into outdoor soil or carefully remove them from your medium into a pot.
Plants remaining indoors for more than 5 weeks need to be transplanted into larger pots. New (or old & well-cleaned) 4” nursery bedding pots and a good organic potting soil are most commonly used. Carefully lift a seedling by holding a true leaf while gently loosening the medium below the roots at the same time. Place the seedling into a pot partially filled with potting soil. Hold the seedling slightly below its final height and gently raise it as you sprinkle more potting soil around the roots. The final height should be the same as it was before transplanting. For potted seedlings, carefully remove the cell and plant it at the same height. Or tear the bottom off of a peat-pot or cow-pot and place it into new soil. Water very gently to settle the soil around the disturbed roots. Fertilize weekly with seaweed and a dilute organic fertilizer.Â
“Hardening” is the process of helping a plant transition from a protected indoor or greenhouse environment to our harsh outdoor conditions of fluctuating temperatures, frost, low humidity, desiccating wind, and intense sun exposure. The seedlings from indoors are too tender to go directly outside in our mountain environment. A transition period of a little more sun and cold every day for a couple of weeks is necessary for them to handle the full force of our outdoors. Hardening was challenging before we began using spun-bonded polyester, insulating floating row-covers in the mid 1980’s. Row-cover (“frost-cloth”) diffuses our high-elevation sunlight while retaining humidity and warmth. Cover seedlings with up to 3 layers of row-cover for several days and bring the seedlings in at night. After several days peel-off a layer of row cover. Maintain two layers for several more days. Using one layer for several days or for weeks (or all season) makes hardening easy. Most plants will thrive all summer under a single layer of row-cover. Be sure to watch the weather. The 1.5 oz floating row-cover (1.5 oz / sq. yd. = 50g / sq. m.) only gives 6-8ºF of frost protection, maybe ~10º with 2-3 layers. Don’t risk leaving them out overnight if temps are low. Many species can never tolerate frost.
When planting, by seed or by transplant, prepare your seedbed garden soil at least a week before planting. Adding fresh mature compost, worm castings, manure and organic fertilizers helps tremendously. If the soils have been built and worked for years, just scratch the new mixture into the top 4-8”. If the bed is new, mix more compost, manure and fertilizers deeply into the bed or ground for at least three seasons. Many gardeners add a final thin layer of high quality potting soil to the very top. Water the beds well and rake them even and smooth. If you have time, cover your garden area with a tarp for a week or so to warm the soil before planting. Do not cover existing perennial plants.
Timing of seed sowing outdoors depends on the species and variety and while seed packets have instructions, they must be viewed through the lens of OUR climate. Most instructions are based on “average last date of frost” = a < 50% chance of a < 32ÂşF night. Location dependent, our actual “date” is mid- to late June (earlier at higher elevations in town and later in cold low spots). Our season is short; plant as early as possible and be cautious. Use plant protection and season extending techniques like floating row-cover, cloches, cold frames, rock walls, water bottles, etc…, to help early plantings survive frost. Row-cover can remain on your beds all summer long to keep your beds warm and humid for a more fruitful gardening season.
*This is a generalization. For more information see Villager Nursery’s Vegetable Gardening hand-outs. | ||||||||||||||||||